UBC Theses and Dissertations

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UBC Theses and Dissertations

A neurobehavioral investigation of orienting behavior Midgley, Glenda C. 1978

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A N e u r o b e h a v i o r a l I n v e s t i g a t i o n o f O r i e n t i n g B e h a v i o r by G l e n d a C. M i d g l e y M.A. , C a r l e t o n U n i v e r s i t y , 197^ A THESIS SUBMITTED I N PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE,OF • DOCTOR OF PHILOSOPHY i n THE FACULTY OF GRADUATE STUDIES (DEPARTMENT OF PSYCHOLOGY) We a c c e p t t h i s t h e s i s as- c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA © G l e n d a C. M i d g l e y , 1978 In p r e s e n t i n g t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the requ i rement s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h Co lumb ia , I ag ree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s tudy . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by the Head o f my Department o r by h i s r e p r e s e n t a t i v e s . It i s u n d e r s t o o d tha t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i thout my w r i t t e n p e r m i s s i o n . Depa rtment The U n i v e r s i t y o f B r i t i s h Co lumbia 2075 W e s b r o o k P l a c e V a n c o u v e r , C a n a d a V6T 1W5 Date i i ABSTRACT Models o f t h e n e u r a l "basis o f v i s u a l l y g u i d e d "behavior s u g g e s t t h a t t h e mammalian b r a i n has two i n d e p e n d e n t v i s u a l s y s t e m s : one i n v o l v e d i n p a t t e r n v i s i o n , and t h e o t h e r i n v o l v e d i n o r i e n t i n g t o v i s u a l s t i m u l i . O r i e n t i n g was measured i n t h i s s e r i e s o f s t u d i e s by e x a m i n i n g "both t h e t h i r s t y r a t ' s a b i l i t y t o d i s r u p t l i c k i n g i n r e s p o n s e t o t h e p r e s e n t a t i o n o f v i s u a l and a u d i t o r y d i s p l a y s and t h e a n i m a l ' s head and p o s t u r a l r e s p o n s e s t o t h e d i s p l a y s . H a b i t u a t i o n o f o r i e n t i n g b e h a v i o r w i t h r e p e a t e d p r e s e n t a t i o n o f a d i s p l a y , and d i s h a b i t u a t i o n t o t h e subsequent i n t r o d u c t i o n o f changes i n i t were a l s o examined. The e f f e c t on t h i s b e h a v i o r o f v a r i o u s l y s i z e d c o r t i -c a l and s u b c o r t i c a l l e s i o n s o f t h e v i s u a l s y s t e m and t h e i n f l u e n c e o f e x t r i n s i c and i n t r i n s i c v a r i a b l e s were a s s e s s e d . The i n v e s t i g a t i o n r e v e a l e d t h a t l e s i o n s o f t h e s u p e r i o r c o l l i c u l u s dov.not r e s u l t i n v i s u a l a g n o s i a o r t h e i n a b i l i t y t o p e r -f o r m t h e a p p r o p r i a t e motor r e s p o n s e s i n v o l v e d i n o r i e n t i n g ; r a t h e r , w h i l e t h e o r i e n t i n g r e s p o n s e i s a v a i l a b l e i n t h e b e h a v i o r a l r e p e r t o i r e o f t h e l e s i o n e d a n i m a l , i t i s n o t a l w a y s e m i t t e d i n r e s p o n s e t o t h e v i s u a l d i s p l a y s t h a t t h e i n t a c t " a n i m a l s t r e a t as l e s s s a l i e n t . The s u p e r i o r c o l l i c u l u s l e s i o n e d a n i m a l s do o r i e n t t o a n c L l l o c a l i z e v i s u a l d i s p l a y s w h i c h a r e more s a l i e n t f o r t h e i n t a c t a n i m a l . F u r t h e r , t h e d e f i c i t i n o r i e n t i n g t o t h e " l e s s " s a l i e n t s t i m u l u s d i s p l a y s c a n be r e d u c e d o r e l i m i n a t e d by c h a n g i n g t h e d e g r e e o f w a t e r d e p r i v a t i o n p r i o r t o t e s t i n g and t h e y a r e c a p a b l e o f u s i n g t h i s d i s p l a y as a s i g n a l o f s h o c k . i i i L e s i o n s r e s t r i c t e d t o a v e r y s m a l l p o r t i o n o f t h e l a t e r a l edges o f t h e deep l a y e r s o f t h e s u p e r i o r c o l l i c u l u s and t h e d o r s a l tegmentum had t h e same consequences as s u p e r i o r c o l l i c u l u s l e s i o n s , • w h i l e l e s i o n s w h i c h i n c l u d e d o n l y t h e s u p e r f i c i a l l a y e r s o f t h e s u p e r i o r c o l l i c u l u s d i d n o t . L e s i o n s o f t h e s t r i a t e and e x t r a s t r i a t e c o r t e x d i d n o t s i g n i f i c a n t l y a f f e c t o r i e n t i n g * b e h a v i o r . R a t s w i t h l e s i o n s o f t h e s u p e r f i c i a l or- deep l a y e r s o f t h e s u p e r i o r c o l l i c u l u s and r a t s w i t h l e s i o n s i n c l u d i n g a r e a 7 o f c o r t e x as w e l l as t h e s t r i a t e and e x t r a s t r i a t e c o r t e x , d i d , h o w e v e r , h a b i t u a t e more q u i c k l y t h a n i n t a c t a n i m a l s t o t h e r e p e a t e d p r e s e n t a t i o n o f t h e v i s u a l d i s -p l a y s , and g e n e r a l l y d i d n o t d i s h a b i t u a t e i n r e s p o n s e t o t h e changes i n t h e v i s u a l d i s p l a y s . These f i n d i n g s s u g g e s t a r e l a t i o n s h i p - b e t w e e n t h e ; c o r t e x , t h e s u p e r f i c i a l l a y e r s , and t h e deep l a y e r s o f t h e s u p e r i o r c o l l i c u -l u s and t h e a b i l i t y o f a n i m a l s t o s h i f t a t t e n t i o n w i t h i n a s t i m u l u s m o d a l i t y . The deep l a y e r s o f t h e s u p e r i o r c o l l i c u l u s may a l s o be i m p o r t a n t f o r s h i f t s o f a t t e n t i o n between s t i m u l u s m o d a l i t i e s ( J a n e , Levey, & C a r l s o n , 1972). O v e r a l l , t h e s e r e s u l t s were d i s c u s s e d w i t h r e g a r d t o a p o s s i b l e m o d u l a t i n g . r o l e - o f t h e s u p e r i o r - c o l l i c u l u s and c o r t e x i n o r i e n t i n g b e h a v i o r and i n terms o f t h e p a r a m e t e r s o f o r i e n t i n g w h i c h must be t a k e n i n t o a c c o u n t i n t h e development o f an adequate model o f t h e n e u r a l b a s i s o f o r i e n t i n g b e h a v i o r . ABSTRACT TABLE OF CONTENTS • L I S T OF -FIGURES :• L I S T OF .TABLES, '" L I S T OF APPENDIXES. INTRODUCTION EXPERIMENT I I n t r o d u c t i o n Method R e s u l t s D i s c u s s i o n EXPERIMENT I I I n t r o d u c t i o n Method R e s u l t s D i s c u s s i o n EXPERIMENT I I I I n t r o d u c t i o n Method R e s u l t s D i s c u s s i o n EXPERIMENT I V I n t r o d u c t i o n TABLE OF CONTENTS i i i v v-i v i i i v i i i 1 19 19 22 29' >2 m. 51 51 52-53 62 G\ 6k V Method 65 R e s u l t s 68 D i s c u s s i o n 75 EXPERIMENT V 77 I n t r o d u c t i o n 77 Method 78 R e s u l t s 79 D i s c u s s i o n 83 EXPERIMENT VI 85 I n t r o d u c t i o n 85 Method 86 R e s u l t s 89 D i s c u s s i o n 95 GENERAL DISCUSSION 98 REFERENCES 119 APPENDIX A 1-27 APPENDIX B 146 APPENDIX C 152 APPENDIX D 156 APPENDIX E 162 APPENDIX F 167' v i L I S T OF FIGURES F i g u r e 1. The g e n i c u l o - s t r i a t e pathway o f the c a t . 3 F i g u r e 2. V i s u o m o t o r mechanisms i n t h e S y r i a n h amster. 6 F i g u r e 3« S c h e m a t i c f l o w d i a g r a m i n d i c a t i n g t h e m a j o r connec-t i o n a l r e l a t i o n s h i p s o f the t h a l a m i c and c o r t i c a l v i s -u a l a p p a r a t u s . 13 F i g u r e The a p p a r a t u s u s e d t o examine d i s r u p t i o n o f l i c k i n g i n r e s p o n s e t o the p r e s e n t a t i o n o f t h e l i g h t d i s p l a y . 2h F i g u r e 5 ( a _ e ) - Mean number o f l i c k s d u r i n g t h e - b a s e l i n e and d u r i n g , 4he". p r e s e n t a t i o n "of the a p p a r e n t l y , moving and s t a t i o n a r y , l i g h t d i s p l a y s . ' 3© F i g u r e 6. The head and body movements e l i c i t e d by t h e p r e s e n t a t i o n o f a l i g h t d i s p l a y . 31 F i g u r e 7C.A-D). R e p r e s e n t a t i v e s e c t i o n s d e p i c t i n g t h e e x t e n t o f dam-age t o SC and s u r r o u n d i n g t i s s u e and c o r t i c a l damage. 3^  F i g u r e 8 ( a - c ) . H i s t o l o g i c a l r e c o n s t r u c t i o n s and b e h a v i o r a l r e s u l t s f o r i n d i v i d u a l SG l e s i o n e d a n i m a l s . 35 F i g u r e 9 ( a - c ) . H i s t o l o g i c a l r e c o n s t r u c t i o n s and b e h a v i o r a l r e s u l t s f o r i n d i v i d u a l " SP l e s i o n e d a n i m a l s . 37 F i g u r e 10(a-c). H i s t o l o g i c a l r e c o n s t r u c t i o n s and b e h a v i o r a l r e s u l t s f o r i n d i v i d u a l ST l e s i o n e d a n i m a l s . H^ O F i g u r e l l ( a - e ) . Mean number o f l i c k s d u r i n g t h e b a s e l i n e and d u r i n g t h e p r e s e n t a t i o n o f t h e a u d i t o r y " t o n e . k8 F i g u r e 12(a-e). Mean number o f l i c k s d u r i n g t h e b a s e l i n e and' •' during«the .:.presenta£ld.n- .of. t h e , l i g h t .-.displays, w i t h . t h e r e d p l a s t i c f i l t e r s . r e m o v e d . • 55 F i g u r e 13(A-D). R e p r e s e n t a t i v e s e c t i o n s d e p i c t i n g the e x t e n t o f damage t o SG and s u r r o u n d i n g t i s s u e and c o r t i c a l damage. 57 F i g u r e . l 4 ( a - b ) . H i s t o l o g i c a l r e c o n s t r u c t i o n s and b e h a v i o r a l r e s u l t s f o r i n d i v i d u a l SP l e s i o n e d a n i m a l s f o r l i g h t d i s p l a y s w i t h the- r e d p l a s t i c f i l t e r s removed. 59 F i g u r e 15(a-e). Mean number o f l i c k s d u r i n g t h e b a s e l i n e and d u r i n g t h e p r e s e n t a t i o n o f t h e " a p p r o a c h i n g " l i g h t d i s p l a y s . 70 v i i F i g u r e 16(A T D). R e p r e s e n t a t i v e s e c t i o n s d e p i c t i n g t h e e x t e n t of damage t o SG and s u r r o u n d i n g t i s s u e 71 F i g u r e i7(A-D). Mean number o f l i c k s d u r i n g t h e b a s e l i n e and d u r i n g t h e p r e s e n t a t i o n o f t h e c i r c l i n g l i g h t d i s -p l a y . 73 F i g u r e 18(A-D). R e p r e s e n t a t i v e s e c t i o n s d e p i c t i n g t h e e x t e n t o f damage t o SG and s u r r o u n d i n g t i s s u e and c o r t i c a l damage. 74 F i g u r e 19(a-d). Mean number o f l i c k s d u r i n g t h e b a s e l i n e and d u r i n g t h e p r e s e n t a t i o n o f t h e " a p p a r e n t l y " moving l i g h t d i s p l a y . 80 F i g u r e 20(A-G). R e p r e s e n t a t i v e s e c t i o n s d e p i c t i n g t h e e x t e n t o f damage t o SC and s u r r o u n d i n g t i s s u e . 82 F i g u r e 21. Mean number o f t r i a l s t o c r i t e r i o n s u p p r e s s i o n and v a r i a n c e f o r SH, SG, SP, DP and ST l e s i o n e d a n i m a l s . 90 F i g u r e 22(a-e). Mean number o f l i c k s d u r i n g t h e b a s e l i n e and d u r i n g t h e p r e s e n t a t i o n o f t h e " a p p a r e n t l y " moving l i g h t d i s p l a y s w h i c h were f o l l o w e d b y an u n a v o i d a b l e f o o t shock. 92 F i g u r e 23(A-D). R e p r e s e n t a t i v e s e c t i o n s d e p i c t i n g t h e e x t e n t o f damage t o SG and s u r r o u n d i n g t i s s u e and c o r t i c a l damage. 93 F i g u r e 24. A s c h e m a t i c d i a g r a m o f the • r e l a t i o n s h i p s ^ - b e t w e e n " • •;- -the- b e h a v i o r a l i m p a i r m e n t o f o r i e n t i n g and l e s i o n s o f the v i s u a l s y s tem. • • I l l F i g u r e 25(a-d). Mean number o f l i c k s d u r i n g t h e b a s e l i n e and d u r i n g the p r e s e n t a t i o n o f t h e " a p p a r e n t l y " ' m o v i n g l i g h t d i s p l a y s . 148 F i g u r e 26(A-C). R e p r e s e n t a t i v e s e c t i o n s d e p i c t i n g t h e e x t e n t o f damage t o t h e SG and s u r r o u n d i n g t i s s u e . 149 F i g u r e 27(A-G). (A) R e p r e s e n t a t i v e s e c t i o n s d e p i c t i n g the e x t e n t o f damage t o t h e SG and s u r r o u n d i n g t i s s u e . (B) Mean number o f l i c k s d u r i n g t h e b a s e l i n e and ' , d u r i n g t h e p r e s e n t a t i o n o f t h e s o l i d l i g h t d i s p l a y s . 154 v i i i F i g u r e 28. A h i s t o l o g i c a l r e c o n s t r u c t i o n o f t h e r a t ' s s u p e r i o r c o l l i c u l u s s h o w i n g t h e 7 l a m i n a e and t h e d i v i s i o n i n t o s u p e r f i c i a l and deep l a m i n a e . 165 i x LIST OF TABLES Table 1. Assignment of Animals, Experiment VI. 87 LIST OF APPENDICES APPENDIX A. Analysis of variance F tables. 127 APPENDIX B. Counterbalanced presentation of stationary and "apparently" moving light displays. 146 APPENDIX C. The effect of increased intensity per se on orienting. 152 APPENDIX D. The effect of visual cortex and subcortical lesions on open f i e l d activity. 155 APPENDIX E. The effect of geniculo-striate and tecto-pulvinar inputs to the cortex on orienting. 1.60 APPENDIX F. Figure 28. 165 X ACKNOWLEDGEMENTS I w o u l d l i k e t o t h a n k Dr. R i c h a r d C. Tees and t h e o t h e r members o f my a d v i s o r y committee: Dr. rD. P a p p a g e o r g i s , Dr. A. G. P h i l l i p s and Dr. D. M. W i l k i e f o r t h e i r a s s i s t a n c e and d i s c u s s i o n s i n t h e p r e p a r a t i o n o f t h i s t h e s i s . I am a l s o g r a t e f u l f o r t h e s. a s s i s t a n c e o f L i n c o l n Chew, Jo h n N e s b i t t and Dr. Di. M. W i l k i e i n t h e development o f t h e b e h a v i o r a l t e s t i n g equipment and t o F r e d L e P a i n e , Derek Van d e r Kooy and P e t e r Van Oot f o r a s s i s t a n c e w i t h h i s t o l o g i c a l and s u r g i c a l p r o c e d u r e s . A warm t h a n k you i s a l s o e x t e n d e d t o a l l t h e g r a d u a t e s t u d e n t s and o t h e r members o f t h e B i o p y s c h o l o g y Department who a s s i s t e d b y h e l p f u l d i s c u s s i o n and encouragement. I woul d l i k e t o t h a n k Ken P r k a c h i n f o r h i s a s s i s t a n c e w i t h t h e g r a p h i c s and f o r h i s encouragement and co m r a d e s h i p d u r i n g t h e p r e p a r a t i o n o f t h i s t h e s i s . F i n a l l y , a s p e c i a l t h a n k s i s e x t e n d e d t o Rod Midgley,whose c o n t r i b u t i o n s t o t h i s t h e s i s c a n n o t b e ' l i s t e d . H i s encouragement and s u p p o r t made b e i n g a g r a d u a t e s t u d e n t b e a r a b l e and o f t e n e n j o y a b l e . 1. INTRODUCTION I n a l l v e r t e b r a t e s t h e r e t i n a has a t l e a s t t h r e e m a j o r p r o j e c t i o n s : t h e t h a l a m i c , t e c t a l , and p r e t e c t a l pathways. 'These pathways c o u l d r e p r e s e n t t h r e e s e p a r a t e v i s u a l systems' w i t h e i t h e r d i r e c t o r i n d i r e c t a c c e s s t o t h e m u s c u l a t u r e i n v o l v e d i n v i s u a l l y g u i d e d b e h a v i o r ( S p r a g u e , L e v e y , D i b e r a r d i n o , & B e r l u c c h i , 1977).'' I n non-mammalian v e r t e b r a t e s , models o f t h e n e u r a l b a s i s o f v i s u a l l y g u i d e d b e h a v i o r have emphasized t h e r e t i n o - t e c t a l p a t h -way. The t e c t u m has been c o n s i d e r e d t h e e s s e n t i a l l i n k i n t h e t r a n s -f o r m a t i o n o f v i s u a l i n f o r m a t i o n i n t o a d a p t i v e motor p a t t e r n s and t h e " h i g h e s t i n t e g r a t i v e c e n t e r " i n t h e m e d i a t i o n o f v i s u a l l y g u i d e d b e h a v i o r ( i n g l e & Sprague, 1975)-I n mammalian s p e c i e s a t t e m p t s t o model t h e n e u r a l b a s i s o f v i s u a l l y g u i d e d b e h a v i o r have e m p h a s i z e d t h e r e t i n o - t h a l a m i c pathway t o t h e s t r i a t e c o r t e x . T h i s t h a l a m i c pathway ( t h e g e n i c u l o -s t r i a t e system) has been c o n s i d e r e d e s s e n t i a l f o r p a t t e r n d i s c r i m i n a -t i o n , t h e e v a l u a t i o n o f t h e b e h a v i o r a l s i g n i f i c a n c e .of v i s u a l s t i m u l i , and t h e t r a n s f o r m a t i o n o f v i s u a l i n f o r m a t i o n i n t o a d a p t i v e motor b e h a v i o r s (Sprague e t a l . , 1977). The r e t i n o - t e c t a l , r e t i n o - p r e t e c t a l , a n d o t h e r r e t i n o f u g a l pathways have g e n e r a l l y been t h o u g h t o n l y t o m e d i a t e " s i m p l e r e f l e x i v e b e h a v i o r s " , s u c h as o r i e n t a t i o n and p u p i l -l a r y a d j u s t m e n t s t o l i g h t . These r e f l e x i v e v i s u a l b e h a v i o r s and t h e i r s u b c o r t i c a l s u b s t r a t e s have been t h o u g h t t o o p e r a t e i n d e p e n -d e n t l y and w i t h o u t i n f l u e n c e o f t h e c o r t i c a l p a t t e r n a n a l y s i n g 2. and i n t e g r a t i v e s y s t e m ( e . g . , S c h n e i d e r , 196?,'1969)• The models w h i c h emphasize t h e g e n i c u l o - s t r i a t e pathway a r e p r i m a r i l y b a s e d on f i n d i n g s w h i c h s u g g e s t e d t h e i m p o r t a n c e o f t h e s t r i a t e c o r t e x ( a r e a 17) f o r p a t t e r n v i s i o n . I n r a t ( L a s h l e y , 1935), hamster ( S c h n e i d e r , 1969), c a t ( S m i t h , 1937), dog (Wing & S m i t h , 19^2), and monkey ( K l u v e r , 19^1, 19^2, 1951), l e s i o n s of. n e o c o r t e x w h i c h i n c l u d e d a r e a 17 have been r e p o r t e d t o r e s u l t i n t h e l o s s o f p a t t e r n v i s i o n . The p r o p o s i t i o n t h a t t h e s t r i a t e c o r t e x was n e c e s s a r y f o r p a t t e r n v i s i o n was a l s o b o l s t e r e d b y t h e e l e c t r o p h y s i o l o g i c a l s t u d i e s o f H u b e l and W i e s e l (1962, I965, 1968). A s c h e m a t i c v e r s i o n o f t h e i r model i s p r e s e n t e d i n F i g u r e 1. B a s e d on t h e i r f i n d i n g s o f i n c r e a s i n g l y complex r e c e p t i v e f i e l d p r o p e r t i e s o f neurons as one p r o g r e s s e d f r o m r e t i n a t o l a t e r a l g e n i c u l a t e n u c l e u s (LGN), t o c o r t i c a l a r e a s 17, 18, and 19, t h e y p r o p o s e d a n arrangement i n w h i c h t h e r e c e p % t i v e f i e l d - p r o p e r t i e s o f t h e c e l l s o f a r e a 17 were t h e r e s u l t o f co n -v e r g e n c e o f s i m p l e r LGN p r o c e s s e s . A r e a 17 c e l l p r o c e s s e s , i n t u r n , c o n v e r g e on t h e c e l l s o f a r e a 18 and 19 and t h i s c o n v e r g e n c e r e s u l t e d i n t h e complex and hyp e r c o m p l e x r e c e p t i v e f i e l d p r o p e r t i e s and t h e s e l e c t i v e r e s p o n d i n g o f c e l l s i n t h e s e a r e a s t o l i n e s and edges o f o p t i m a l s i z e and o r i e n t a t i o n ( i . e . , p a t t e r n s ) . The p r e s e n c e o f c e l l s i n s t r i a t e c o r t e x w h i c h r e s p o n d e d s e l e c t i v e l y t o l i n e s and c o n t r a s t i n g edges s u g g e s t e d t h a t t h i s a r e a was t h e n e u r a l s u b s t r a t e o f t h e f e a t u r e a b s t r a c t i o n p r o c e s s i n v o l v e d i n p a t t e r n v i s i o n . W h i l e t h e d i s c o v e r y o f t h e s e c e l l s d i d 3 A . F i g u r e 1. The g e n i c u l o s t r i a t e pathway o f the c a t showing, a t each l e v e l , t h e r e c e p t i v e f i e l d s o f t h e neurons and t h e i r t r i g g e r f e a t u r e s o r o p t i m a l s t i m u l i . + = ON response;--- =. OFF r e s p o n s e . (From B a r l o w , Narasimhan, & R o s e n f e l d , 1972). 3 B. O b j e c t R e t i n a R e c e p t i v e F i e l d s T r i g g e r F e a t u r e s + - _ + + - ~ r + + - - + + --_ + + + + + Complex Moving Edges E t c . Appear t o be com-b i n a t i o n s o f s i m p l e u n i t s o f same o r i e n -t a t i o n and/or d i s -p a r i t y . L o c a l B r i g h t e n i n g L o c a l Dimming L o c a l B r i g h t e n i n g L o c a l Dimming Moving, S l i t s , B a r s , o r Edges, £ ~ of S p e c i f i c + O r i e n t a t i o n and B i n o c u l a r D i s -p a r i t y . Hyper Complex I I L i n e Segments, C o r n e r s , E t c . P o s s i b l y formed from p a i r s o f Hyper Complex I . Ends of L i n e s . E t c . P o s s i b l y e x c i t e d by one.Complex and i n -h i b i t e d ' by o t h e r s of same o r i e n t a t i o n . 4. l e n d c r e d e n c e t o the models w h i c h e m p h a s i z e d the i m p o r t a n c e o f a r e a 17 t o a f e a t u r e a b s t r a c t i n g s y s t e m , i t has n o t been demonstra-t e d t h a t t h e s e c e l l s a r e n e c e s s a r y and s u f f i c i e n t f o r p a t t e r n v i s i o n o r even t h a t t h e y r e p r e s e n t a n e c e s s a r y f i r s t s t a g e i n the p r o p o s e d s y s t e m . A t t e m p t s have been made t o e x t e n d H u b e l and W i e s e l ' s (1962, I965) b a s i c s e r i a l .model, t o i n c l u d e a - s t a g e i n w h i c h t h e . b e h a v i o r a l s i g n i f i c a n c e o f p a t t e r n e d v i s u a l s t i m u l i i s ".evaluated" ( J o n e s & ' M i s h k i n , 1972). I t was h y p o t h e s i z e d t h a t the c o n t o u r and edge ( o r p a t t e r n ) a n a l y s i s a c c o m p l i s h e d by a r e a s 17, 18, 19*and t h e t e m p o r a l c o r t e x i s f o l l o w e d by a f u r t h e r s t a g e i n wh i c h t h e m o t i v a t i o n a l o r e m o t i o n a l s i g n i f i c a n c e o f t h e s t i m u l i i s d e t e r m i n e d . T h i s s t a g e i n t h e sequence g e n e r a l l y has.been i d e n t i f i e d w i t h t h e l i m b i c s y s t e m . T h i s e x t e n s i o n o f t h e model.has reeeived-.some e x p e r i m e n t a l ( t h o u g h . e q u i v o c a l ) s u p p o r t . B i l a t e r a l d e s t r u c t i o n o f t h e t e m p o r a l l o b e s , a d j a c e n t c o r t i c a l a r e a s , hippocampus,and amygdala have been r e p o r t e d t o r e s u l t i n t h e K l u v e r and Bucy (1939) syndrome o f " p s y c h i c b l i n d n e s s " ; ( t h e i n a b i l i t y t o d i f f e r e n t i a t e f o o d f r o m n o n - f o o d o b j e c t s ) and e x c e s s i v e and m i s d i r e c t e d e m o t i o n a l i t y w i t h r e s p e c t t o v i s u a l s t i m u l i . T h i s i m p a i r m e n t has been v i e w e d as r e s u l t i n g f r o m t h e d i s -s o c i a t i o n o f t h e a n a l y s i s o f v i s u a l s t i m u l i by t h e s t r i a t e , e x t r a s t r i -a t e , =and t e m p o r a l s y s t e m f r o m t h e d e t e r m i n a t i o n o f t h e i r a s s o c i a t i o n a l o r e m o t i o n a l s i g n i f i c a n c e by t h e l i m b i c s y s t e m ( H o r e l , K e a t i n g , & M i s a n t o n e , 1975; J o n e s f & M i s h k i n , 1972), o r v i a t h e l i m b i c system's c o n n e c t i o n s t o t h e hypothalamus ( R o l l s , Judge, & Sanghera, 1977). 5. While these notions about the anatomical basis of visually guided behavior have in i t i a t e d extensive research, acceptance of the models i s clearly premature. The models involve untested assumptions with respect to both the underlying anatomical substrates and the nature of sensory-perceptual and associational processes. Of prime concern to the present investigation i s , however, the dependence of these models on the geniculo-striate system and limbic system as the sole integrative mechanism and the failure to consider other retino-fugal pathways to the limbic system. Schneider (1967, I969) has presented another model of visually guided behavior which extends Hubel and Wiesel's ideas and exp l i c i t l y treats the transformation of visual information into adaptive motor behaviors. A schematic version of Schneider's two visual system hypothesis i s presented i n Figure 2. In keeping with Hubel and Wiesel's model, he proposed that the geniculo-striate system was responsible for pattern vision. The appropriate motor responses to patterned visual stimuli were-assumed to occur at a later stage through the geniculo-striate's connections to the motor system. On the other hand, the tectal system (superior colliculus) and i t s subcortical motor connections were suggested to function reflexively i n response to visual stimuli: to i n i t i a t e appropriate head and eye movements required to orient to, and localize stimuli. A l l of these models have been valuable i n generating research. They have, however, also provoked a number of important criticisms and the collection of data which suggest substantial Figure 2. Visuomotor mechanisms i n the Syrian hamster. The flow of information from the retina to two subsystems for motor con-t r o l i s represented in accordance with 3 experimental studies of neuroanatomical connections- and behavioral effects of surgical lesions. Top to bottom in the diagram.corresponds with rostral to caudal i n the brain. LGd = dorsal nucleus of l a t e r a l geniculate body; LP = nucleus later a l i s posterior of thalamus. (Schneider, 1975). 6 b. Striate Cor tex L J Juxtastriate Cor tex Subsystem for control of go / no-go responses I Subsystem for control of head turning and associated postura 1 adjustments I I revisions are needed. Before-reviewing the research involved'"with these questions a "brief description of some - of the connections of the three major retinofugal pathways is necessary. (1) The..-Thalamic Projection (Geniculo-Striate System) The., .retinal pathway, to the thalamus terminates in-"the dorsal late r a l geniculate nucleus (LGNd) and :this nucleus sends a ..substan-t i a l projection to the striate cortex (area 17)' i n the posterior neo-cortex (Kreig, 19.46 a, b)., The striate cortex, i n turn, projects to the belt of cortex surrounding area 1? (extrastriate cortex) in a l l mammals•studied to date. .Extras triate cortex has numerous projec-tions to temporal and frontal cortex and the limbic system as des-cribed earlier (see, Chalupa, 1977; Graybiel, 1974; Jones, 1974; and Weiskrantz, 1974, for a complete description). The specific projections beyond area 18 have not been examined for rat; however, i t i s generally assumed that comparable connections exist for this species as for cat and monkey, tree shrew, and hedgehog (Chalupa, 1977; Diamond, 1976; Gould & Ebner, 1978). (2) The Tectal Projection (Tecto-Pulvinar System) The retinal pathway to the superior colliculus (SC) termin-ates i n i t s superficialslayers. In addition to projections which descend from the deep layers of the SG to the oculo-motor nucleus and spinal cord, there i s a substantial projection to the thalamus. The terminal nuclei i n the thalamus vary between species. In rat, the superficial layers are reported to project to the nucleus later-a l i s posterior (NLP), while other thalamic projections • -8 are not known at present (Hughes, 1977). In cats and monkeys, however, the SC projects to the subdivisions of the,posterior nuclei of the thalamus and to the pulvinar (Chalupa, 1977). The thalamic nuclei which receive SC projections (tecto-pulvinar system) i n turn project to the cortex. In rats, the NLP projects to the extrastriate cortex (areas 18 & 18A), to area 7 of the parietal cortex,and to area 20 of temporal cortex (Hughes, 1977). A histological reconstruction of the rat's superior colliculus showing the 7 laminae and the division into •superficial and deep laminae-is presented i n Figure 28,-, of Appendix F. (3) The Pretectal Projection The pretectum of a l l species apparently receives a retinal projection and has descending projections to brainstem nuclei involved i n the pupillary light reflext Cortical projections are not known for rat; however, i n cat and monkey there i s a substantial projection to area 21 of the temporal cortex (Chalupa, 1977). As indicated earlier, there have been a number of important questions and challenges directed at the s e r i a l processing model and i t s extensions and the behavioral significance of each of these 3 pro-jections. F i r s t , i s the geniculo-striate system, i n exclusion of other retinofugal pathways, essential for discrimination of visual stimuli? Second, what i s (are) the role(s) of the subcortical pathways i n visu-a l l y guided behavior? Third, what i s the role of the above connections and interactions between the three major retinofugal pathways i n visu-a l l y guided behavior? Fourth, are orienting and localization appropri-ately described as "simple reflexive behaviors'.'? A brief review of . research stemming from these concerns i s outlined below. 9. The n o t i o n t h a t t h e g e n i c u l o - s t r i a t e pathway i s c r i t i c a l t o p a t t e r n v i s i o n has been examined i n a number o f s p e c i e s . I n r a t (Hughes, 1977), c a t s , ( D o t y , 1971; Sprague e t a l . , 1977), and monkeys ( S c h i l d e r , P a s i k , & P a s i k , 1972) l e s i o n s w h i c h i n c l u d e a r e a 17 and p a r t s o f the e x t r a s t r i a t e c o r t e x ( t h u s r e m o v i n g t h e e n t i r e LGN p r o j e c t i o n t o t h e c o r t e x ) do n o t d e s t r o y p a t t e r n d i s c r i m i n a t i o n s b u t o n l y r e s u l t i n e x t e n d e d l e a r n i n g o r r e l e a r n i n g o f p a t t e r n d i s -c r i m i n a t i o n s . L e s i o n - b e h a v i o r i n v e s t i g a t i o n s i n t r e e shrews p r o v i d e t h e c l e a r e s t i l l u s t r a t i o n o f t h i s i s s u e , s i n c e u n l i k e the'-mammals m e n t i o n e d above, t h e LGN p r o j e c t s e x c l u s i v e l y t o a r e a 17 i n t h i s s p e c i e s . W h i l e t h e models r e v i e w e d e a r l i e r e m phasized t h e s t r i a t e c o r t e x ( a r e a 17) o f mammals as t h e p i v o t a l f i r s t s t a g e i n p a t t e r n p e r c e p t i o n and e x c l u d e d t h e o t h e r r e t i n o f u g a l pathways t o s u b c o r t i c a l v i s u a l l y r e s p o n s i v e a r e a s f r o m i n v o l v e m e n t i n t h i s p r o c e s s , K i l l a c k y , Snyder, and Diamond (1971) and S n y d e r and Diamond (1968) f o u n d t h a t a b l a t i n g a r e a 17 d i d n o t have any c o n s p i c u o u s e f f e c t on t h e a c q u i s -i t i o n o r r e t e n t i o n o f p a t t e r n d i s c r i m i n a t i o n s i n t r e e shrews. A p p a r e n t l y t h e n , t h e g e n i c u l o - s t r i a t e system i s n o t n e c e s s a r y f o r t h i s component o f v i s u a l l y g u i d e d b e h a v i o r and hence a t t e n t i o n must be f o c u s s e d on-'the. p o t e n t i a l r o l e of-' s u b c o r t i c a l - areas- fL 1 1 p a t t e r n v i s i o n . Cooper and h i s c o l l e a g u e s c o m p l e t e d a s e r i e s o f s t u d i e s w h i c h a l s o p r o v i d e a d e m o n s t r a t i o n o f r e s i d u a l p a t t e r n d i s c r i m i n a -t i o n w i t h l e s i o n s o f t h e v i s u a l c o r t e x . S t r i a t e and e x t r a s t r i a t e c o r t e x were removed c o m p l e t e l y ; t h u s , t h e e n t i r e g e n i c u l o - s t r i a t e 1 o. and most o f t h e t e c t o - p u l v i n a r s ystem's p r o j e c t i o n s t o c o r t e x were e l i m i n a t e d . The s t r i a t e a nd e x t r a s t r i a t e a b l a t e d r a t s were c a p a b l e o f u s i n g s p a t i a l v i s i o n ( F e r r i e r & Cooper, 1976)-.- -Moreover, d i s c r i m -i n a t i o n o f f l u x - e q u a t e d p a t t e r n e d ' v i s u a l s t i m u l i was l e s s i m p a i r e d -by s t r i a t e and e x t r a s t r i a t e l e s i o n s t h a n by an o c c l u s i o n p r o c e d u r e w h i c h e l i m i n a t e d c o n t o u r o r p a t t e r n cues b u t l e f t l o c a l l u m i n o u s f l u x d i f f e r e n c e s ( M i l l e r , 1973; M i l l e r & Cooper, 1974). A t t e m p t s t o examine t h e c o n t r i b u t i o n o f a l l t h e i n d i v i d u a l s u b c o r t i c a l p r o j e c t i o n s o f t h e r e t i n a and t h e i r c o r t i c a l p r o j e c t i o n s have n o t been u n d e r t a k e n . However, some i n d i c a t i o n s o f t h e c o n t r i b u t i o n o f t h e ma j o r s u b c o r t i c a l r e t i n a l p r o j e c t i o n s i n t h e r a t a r e a v a i l a b l e . B l o c h e r t , F e r r i e r , and Cooper (1976) have examined t h e c o n t r i b u t i o n o f p r e t e c t a l l e s i o n s t o u t i l i z a t i o n o f t o t a l l u m i n o u s f l u x cues and f o u n d a d r a s t i c i m p a i r m e n t by p r e t e c t a l l e s i o n s o f a d i s c r i m i n a t i o n i n w h i c h o n l y f l u x cues c o u l d be u s e d . L e s i o n s o f t h e p r e t e c t u r n and t h e LGNv a r e a l s o r e p o r t e d t o i m p a i r a c q u i s i t i o n and r e t e n t i o n o f b l a c k - w h i t e d i s c r i m i n a t i o n s ( B l o c h e r t e t a l . , 1976; H o r e l , 1968; L e g g & Cowey, 1977), b u t n o t s t r i p e o r i e n t a t i o n d i s c r i m i n a t i o n s . - I t ap p e a r s t h a t t h e s u b c o r t i c a l p r e t e c t u m i s .preeminent', i n i n t e n s i t y -d i s c r i m i n a t i o n s when t h i s cue i s a v a i l a b l e f o r t h e s o l u t i o n o f a d i s c r i m i n a t i o n ( B l o c h e r t e t a l . , 1976). S i n c e p a t t e r n s i n v o l v e l o c a l changes i n l i g h t i n t e n s i t y , t h e s e d a t a s u g g e s t t h a t t h e p r e -t e c t u m may be i n v o l v e d i n some a s p e c t o f p a t t e r n d i s c r i m i n a t i o n ' . The... r o l e • o f t h e SC i n p a t t e r n - v - i s i o h ^ a l s o has been examined. _A number -of s t u d i e s i n r a t (C o o p e r , B l a n d , G i l l e s p i e , & 11 . Whitaker, 1970; Dyer, Marino, Johnson,& Kruggel, 1976; Thompson, 1969), golden hamster (Schneider, 1969). and rhesus monkey (Anderson & Symmes, 1969; Rosvold,. Mishkin,& Scharzhart, 1969)? indicate mini-mal ( i f any) d e f i c i t i n postoperative retention of a pattern...discim-ination after lesions of the SC. However, i n cats (Anderson & William-son, 1971; Berlucchi,. Sprague, Levey, & DiBerardino, 1972; Myers, 196^ ; Sprague, Berlucchi, & DiBerardino, 1970) and tree shrews (Casagrande & Diamond, 197^), deficits have been reported i n postoper-ative acquisition of a discrimination but not in:'.the retention of a preoperatively learned discrimination. An explanation of why the SC-pretectal lesions interfere with postoperative acquisition of a pattern discrimination but not retention i s not immediately apparent-from the results of these specific studies. A tentative conclusion, however, may be that none of the retinofugal systems is ' c r i t i c a l or pivotal i n these pattern discriminations. Rather, each of the retinofugal pathways may be di f f e r e n t i a l l y responsive to different parameters or dimensions of a stimulus display, such as the intensity and spatial characteristics of particular visual targets. Moreover, anatomical studies demonstrate the presence of connections between the major visual systems providing a substrate for interactions and the reciprocal modulation of neural acitivity,. In. fact,, i t appears that visual systems "are so intimately interconnected that i t i s impossible to conceive of activity i n one, not being .influenced by activity i n the others" (Jones, 197^ , p. 225). 12 A. In a l l mammals studied, the three terminal areas of the retinal projections have overlapping cortical targets. • Jhe.main points of interaction of- the visual areas are described i n the accom-panying diagram (Figure 3, from Jones, 197^, p. 226). In rat, the tectofugal and geniculosstriate system have overlapping projections to extrastriate cortex and perhaps i n areas 20 and ?• Although the striate projections to these areas have not been examined to date, they have, been demonstrated i n other species as cat and monkey (Jones, 197^). The geniculo-striate and tecto-pulvinar systems also over-lap and l i k e l y modulate each other's activity via specific connections between them. There are substantial projections from area 1? to the superficial layers of the superior colliculus in. the rat (Lund, 1966). These connections are reciprocal i n that the superficial laminae of SG are l i k e l y the source of the. l a t e r a l posterior nucleus projections to areas 18, 7# and 20. In cat and monkey, the extrastriate cortex and temporal cortex have descending projections primarily to the deep layers" of the SC (Sprague, 1975) • Similar connections'.likely occur in the rat', however, these have not. been demonstrated to date. In addition to the reciprocal cortico-tectal pathways, a l l the visual cortical areas appear to have reciprocal projections to their thalamic sources. Reciprocal connections between the visually responsive cortical areas and their thalamic sources have been demonstrated i n cat and monkey (cf. Chalupa, 1977). Only a projection of area 17 to the NLP of thalamus has been demonstrated 12 B. Figure 3. Schematic flow diagram indicating the major connec-tional relationships of the thalamic and cortical visual apparatus. (From Jones, 1974). SUPERIOR COLLICULUS AND PRETECTUM PARIETO-TEMPORAL (20, 21, TG, ? others) T PERISTRIATE (areas 18 8 19) FRONTAL STRIATE, (area 17) L P V PULVINAR J 3 i n t h e r a t t o d a t e ( R i b a k & P e t e r s , 1975)• Very l i t t l e d a t a e x i s t on t h e n a t u r e o f a l l t h e i n t e r -a c t i o n s between t h e r e t i n o f u g a l pathways w h i c h one m i g h t e x p e c t on t h e b a s i s o f t h e a n a t o m i c a l c o n n e c t i o n s o u t l i n e d above. However, i n c a t ( W i c k e l g r e n & S t e r l i n g , I969), monkey (Cynader & Berman, 1972) and r a t ( G o o d a l e , 1973) t h e i m p o r t a n c e o f t h e p r o j e c t i o n f r o m t h e s t r i a t e c o r t e x i n m o d u l a t i n g t h e f u n c t i o n o f t h e c e l l s o f t h e s u p e r i o r c o l l i c u l u s has been d e m o n s t r a t e d . A b l a t i o n o r c o o l i n g o f t h e c o r t e x r e s u l t e d i n t h e l o s s o f d i r e c t i o n s e n s i t i v i t y and b i n o c u l a r i t y p r o p e r -t i e s o f s i n g l e c e l l r e s p o n s e s i n t h e s u p e r f i c i a l l a m i n a e o f t h e c a t , th e l o s s o f r e s p o n s i v e n e s s t o v i s u a l s t i m u l i i n t h e deep l a m i n a e o f th e monkey, and a d e p r e s s i o n i n t h e a m p l i t u d e o f v i s u a l l y - e v o k e d p o t e n t i a l s i n t h e s u p e r i o r c o l l i c u l u s o f t h e r a t . These p r e l i m i n a r y f i n d i n g s o f t h e m o d u l a t i o n o f t h e r e s p o n s e c p r o p e r t i e s o f c e l l s I n t h e r e t i n o - t e c t a l pathway by t h e a c t i v i t y o f c e l l s i n t h e g e n i c u l o -s t r i a t e pathway s u g g e s t t h e t h r e e r e t i n o f u g a l pathways a r e n o t i n d e p e n d e n t s y s t e m s . W h i l e t h e n a t u r e o f t h e i n t e r a c t i o n between v i s u a l c e n t e r s as y e t c a n n o t be d e s c r i b e d , a f e w s t u d i e s p o i n t o u t t h e p o t e n t i a l i m p o r t a n c e o f t h e s e dynamic i n t e r a c t i o n s i n a r r i v i n g a t an adequate model o f v i s u a l l y g u i d e d b e h a v i o r . K i r v e l , G r e e n f i e l d , and Meyer (1974), and Sprague (1966) f o u n d t h a t u n i l a t e r a l SG o r s t r i a t e a b l a t i o n s i n r a t s and c a t s r e s u l t e d i n a n absence o f l o c a l i z a t i o n and f o l l o w i n g o f v i s u a l s t i m u l i i n t h e v i s u a l f i e l d c o n t r a l a t e r a l t o t h e l e s i o n , and i p s i v e r s i v e c i r c l i n g when s t i m u l i were p r e s e n t e d 14. i n t h e i p s i l a t e r a l v i s u a l f i e l d . A d r a m a t i c r e c o v e r y f r o m t h e s e b e h a v i o r a l d e f i c i t s was o b s e r v e d when a l e s i o n was s u b s e q u e n t l y p l a c e d i n t h e c o n t r a l a t e r a l c o l l i c u l u s o r when t h e t e c t a l commissure was c u t (Sherman, 1974, 1977)- The r e c o v e r y f r o m c o n t r a l a t e r a l neg-l e c t o f v i s u a l s t i m u l i c a n be c o n s i d e r e d a n i m p o r t a n t d e m o n s t r a t i o n o f a n i n t e r a c t i o n between t h e g e n i c u l o - s t r i a t e s y s t e m and SG. The i p s i v e r s i v e c i r c l i n g i s , however, l i k e l y o n l y a n a r t i f a c t due t o u n i l a t e r a l damage t o t h e motor s y s t e m as Cooper e t a l . (1971) have s u g g e s t e d . Hughes (1977) a l s o p r o v i d e d a n i n t e r e s t i n g i l l u s t r a t i o n o f a n i n t e r a c t i o n o f t h e g e n i c u l o - s t r i a t e system and t e c t o - t h a l a m i c s y s t e m i n . a p a t t e r n d i s c r i m i n a t i o n " i n t h e - r a t . He f o u n d t h a t l e s i o n s o f a r e a 17 a l o n e had o n l y a modest e f f e c t on p o s t o p e r a t i v e l e a r n i n g o f a s t r i p e o r i e n t a t i o n , d i s c r i m i n a t i o n . A n i m a l s ' w i t h l e s i o n s o f NLP ( t h e t h a l a m i c component o f t h e t e c t o - c o r t i c a l system) d i d n o t e x h i b i t any i m p a i r m e n t . o n t h i s k i n d o f p a t t e r n d i s c r i m i n a t i o n r e l a t i v e , t o c o n t r o l s . When, however, b o t h NLP a n d a r e a 17 were a b l a t e d , t h e subsequent i m p a i r m e n t was s i m i l a r t o , .'but n o t q u i t e as d r a m a t i c a s , the permanent d e f i c i t o f p a t t e r n d i s c r i m i n a t i o n s f o l l o w i n g r a d i c a l p o s t e r i o r c o r t i c a l a b l a t i o n s . Thus, perhaps t h e t e r m i n a l a r e a o f b o t h t h e g e n i c u l o - s t r i a t e and t e c t o - p u l v i n a r systems must be l e s i o n e d ' t o i m p a i r p a t t e r n v i s i o n . W h i l e t h e s e s t u d i e s do n o t p r o v i d e a d e s c r i p t i o n o f t h e n a t u r e o f i n t e r a c t i o n s between t h e v i s u a l systems o r t h e d i r e c t i o n o f m o d u l a t i n g i n f l u e n c e s between the systems (i-..e.,'which s y s t e m 1 5. modulates w h i c h ) , t h e y c l e a r l y d e m o n s t r a t e t h e i m p o r t a n c e o f c o n s i d -e r i n g t h e r e l a t i o n s h i p between t h e s y s t e m s . The s e r i a l p r o c e s s i n g m o d e l j a n d i t s e x t e n s i o n s d i c h o t o m i z e d v i s u a l l y g u i d e d b e h a v i o r and t h e n e u r a l s u b s t r a t e s a n d n e g l e c t e d t h e r o l e o f c o n n e c t i o n s between th e s y s t e m s . A l t h o u g h t h e models o f v i s u a l l y g u i d e d b e h a v i o r c a n ( a n d w i l l ) be c r i t i c i z e d i n terms o f t h e i r t r e a t m e n t o f o r i e n t i n g b e h a v i o r as s i m p l e and r e f l e x i v e , t h e r e i s c o n s i d e r a b l e e v i d e n c e t h a t t h e SG has t o be i n v o l v e d i n o r i e n t i n g . The SC i s i d e a l l y l o c a t e d anatom-i c a l l y f o r t h e t r a n s f o r m a t i o n o f v i s u a l i n f o r m a t i o n i n t o a d a p t i v e motor b e h a v i o r . I n mammals, t h e s u p e r f i c i a l lamina.- o f t h e SC ( s t r a t u m o p t i c u m ) i s a m a j o r t e r m i n a l o f t h e t o p o g r a p h i c a l l y o r g a n i z e d r e t i n a l f i b e r s and t h e deep l a m i n a e o f t h e SG a r e a s o u r c e o f f i b e r s t o l o w e r s p i n a l and b r a i n s t e m motor a r e a s ( i n g l e & S p r a g u e , 1975)• E l e c t r i c a l s t i m u l a t i o n o f t h e s e pathways i n f r e e l y moving a n i m a l s s u c h as t h e r a b b i t , c a t and r h e s u s monkey, e l i c i t s t u r n i n g o f head, eye,, and body tow a r d s t h e r e g i o n o f v i s u a l space c o r r e s p o n d -i n g t o t h e a r e a r e t i n o t o p i c a l l y mapped o n t o t h e SC and s t i m u l a t e d by t h e e l e c t r o d e ( i n g l e & S p r a g u e , 1975; S c h a e f e r , 1970; S c h i l l e r . & S t r y k e r , 1972). E l e c t r o p h y s i o l o g i c a l r e c o r d i n g s t u d i e s a l s o s u p p o r t t h e p r o p o s i t i o n t h a t t h e SC i s r e s p o n s i b l e f o r t h e i n i t i a t i o n o f t h e o r i e n t i n g r e s p o n s e and changes i n t h e head and eye p o s i t i o n s w h i c h a l l o w an o r g a n i s m t o s h i f t f i x a t i o n f r o m one v i s u a l s t i m u l u s t o -a n o t h e r . C e l l s i n t h e s u p e r f i c i a l l a y e r s o f t h e SC, whose r e c e p t i v e 16. f i e l d s a r e p e r i p h e r a l t o t h e c e n t e r o f gaze, w i l l i n c r e a s e t h e i r f i r i n g r a t e j u s t p r i o r t o an eye movement w h i c h s h i f t s t h e c e n t e r o f gaze i n t o the c e l l s ' r e c e p t i v e f i e l d (Wurtz & G o l d b e r g , 1972). I n a d d i t i o n , r a t s ( B a r n e s , S m i t h & L a t t s , 1970; K i r v e l e t a l . , 197^)> h a m s t e r s ( S c h n e i d e r , 1969), c a t s ( S p r a g u e , 1966; Sprague & M e i k l e , I965), t r e e shrews (Casagrande & Diamond, 197^ 0 » and monkeys (Denny-Brown, I962) w i t h b i l a t e r a l and u n i l a t e r a l r e m o v a l o f t h e o p t i c t e c t u m o r SG a p p e a r n o t t o o r i e n t , l o c a l i z e , f o l l o w , o r t r a c k v i s u a l s t i m u l i . There i s , t h e r e f o r e , a s u b s t a n t i a l body o f e v i d e n c e w h i c h s u p p o r t s t h e p r o p o s i t i o n t h a t t h e SC p l a y s a s i g n i f i c a n t r o l e i n t h e o r i e n t i n g r e s p o n s e : ( l ) t h e p r e s e n c e o f a t o p o g r a p h i c a l l y o r g a n i z e d s e n s o r y map w i t h more o r l e s s d i r e c t a c c e s s t o t h e o c u l a r and s p i n a l m otor s y s t e m s , (2) the e l e c t r o p h y s i o l o g i c a l e v i d e n c e o f neurons w h i c h r e s p o n d p r i o r t o a s h i f t i n v i s u a l f i x a t i o n , (3) t h e d a t a t h a t o r i e n t i n g c a n be e l i c i t e d b y e l e c t r i c a l s t i m u l a t i o n , and f i n a l l y , (4) t h e l e s i o n - b e h a v i o r f i n d i n g s . However, t h e r e a r e s e v e r a l i m p o r -t a n t a s s u m p t i o n s t h a t have n o t been q u e s t i o n e d o r t e s t e d . F i r s t , i t has n o t been c l e a r l y d e m o n s t r a t e d t h a t t h e SC i s e x c l u s i v e l y r e s p o n -s i b l e f o r o r i e n t i n g w i t h no i n v o l v e m e n t o f g e n i c u l o - s t r i a t e o r o t h e r c o r t i c a l and s u b c o r t i c a l pathways. F u r t h e r , i t i s n o t c l e a r i n t h e models o f v i s u a l l y g u i d e d b e h a v i o r what i s p r e c i s e l y meant b y t h e terms o r i e n t a t i o n and l o c a l i z a t i o n . I 7 R e s e a r c h c o n c e r n e d p r i m a r i l y w i t h t h e n a t u r e o f o r i e n t i n g and i t s h a b i t u a t i o n has c o n c e i v e d o f t h e o r i e n t i n g r e s p o n s e as i n v e s t i g a t o r y r e a c t i o n s t o n o v e l s t i m u l i . These r e a c t i o n s i n c l u d e : p h y s i o l o g i c a l changes w h i c h i n c r e a s e t h e s e n s i t i v i t y o f t h e sense organs and r e s u l t i n l o w e r e d t h r e s h o l d t o a s t i m u l u s , changes i n t h e s k e l e t a l m u s c u l a t u r e r e q u i r e d t o t u r n and d i r e c t t h e s e n s o r y o r g a n t o w a r d s t h e s o u r c e o f t h e s t i m u l u s , changes i n t h e g e n e r a l s k e l e t a l m u s c u l a t u r e w h i c h t e m p o r a r i l y a r r e s t o n g o i n g b e h a v i o r and c o n c u r r e n t autonomic nervous s y s t e m changes ( c f . Lynn, 1966). R e s e a r c h c o n c e r n e d w i t h t h e i n v o l v e m e n t o f t h e SC i n v i s u a l l y g u i d e d b e h a v i o r g e n e r a l l y has . t r e a t e d o r i e n t i n g and l o c a l i z a t i o n as synonymous; A n i m a l s have been r e q u i r e d 7 t o l o c a l i z e and s p e n d an e x t e n d e d amount o f t i m e e x p l o r i n g t h e t e s t s t i m u l u s i n o r d e r t o c o n c l u d e t h a t o r i e n t i n g was n o t i m p a i r e d . The models e i t h e r e x p l i c i t l y (two v i s u a l systems h y p o t h e s i s ) o r i m p l i c i t l y ( s e r i a l p r o c e s s i n g model o f H u b e l and W i e s e l ) s u g g e s t t h a t o r i e n t i n g and l o c a l i z a t i o n o f v i s u a l s t i m u l i a r e s i m p l e , r e f l e x i v e a n d ' u n i t a r y r e s p o n s e s t o n o v e l s t i m u l i t h a t do n o t depend on a n y t h i n g o t h e r t h a n t h e p r e s e n c e o f a s t i m u l u s i n t h e v i s u a l f i e l d and an i n t a c t t e c t u m . The models do n o t i n c l u d e a p r o c e s s w h i c h would a l l o w s e l e c -t i v i t y o f t h i s b e h a v i o r i n r e s p o n s e t o v i s u a l s t i m u l i . O b v i o u s l y , t h e o r i e n t i n g r e s p o n s e can n o t and does n o t o c c u r t o e v e r y v i s u a l s t i m u l u s . The s e l e c t i v i t y o f o r i e n t i n g i s l i k e l y t o be d e t e r m i n e d by b o t h i n t r i n s i c a n d . e x t r i n s i c p a r a m e t e r s . The e f f e c t o f i n t r i n s i c I 8 ( M i n e r , 197*0 o r a t t e n t i o n a l and m o t i v a t i o n a l f a c t o r s ( i n g l e & Sprague, 197*0 on t h e o r i e n t i n g r e s p o n s e has been s u g g e s t e d by r e c e n t s t u d i e s i n amp h i b i a n s ( i n g l e , 1973, 1975)' These p a r a m e t e r s m i g h t i n c l u d e s u c h f a c t o r s as t h e s t a t e o f d e p r i v a t i o n o f t h e o r g a n i s m , p r i o r e x p e r i e n c e w i t h " t h e s t i m u l u s ( e . g . , i t s n o v e l t y o r p r e v i o u s a s s o c i a t i o n w i t h a v e r s i v e o r r e w a r d i n g c o n s e q u e n c e s ) . The p r o p o s i % t i o n t h a t a t t e n t i o n a l , e x p e r i e n t i a l and m o t i v a t i o n a l f a c t o r s i n f l u -ence t h e f e a t u r e a n a l y s i s i n v o l v e d i n shape p e r c e p t i o n and r e c o g n i -t i o n i s w e l l e s t a b l i s h e d ( e . g . , D o d w e l l , 1975) and perhaps a l l t h e same p r o c e s s e s c a n o r may have a s i g n i f i c a n t i m p a c t on o r i e n t a t i o n b e h a v i o r . E x t r i n s i c p a r a m e t e r s o r " a t t e n t i o n - g e t t i n g " p r o p e r t i e s ( M i n e r , 197*+) o f t h e s t i m u l u s may i n c l u d e s u c h c h a r a c t e r i s t i c s as s i z e , d i s t a n c e f r o m t h e o b s e r v e r , i n t e n s i t y , s p a t i a l p o s i t i o n , and m o t i o n r e l a t i v e t o t h e o b s e r v e r . I n a d d i t i o n , t h e s p e c i f i c s p a t i a l and i n t e n s i t y c o n f i g u r a t i o n o f a s t i m u l u s ( i . e . , i t s p a t t e r n ) may be a n i m p o r t a n t d e t e r m i n a n t o f o r i e n t i n g . I f s t i m u l u s c o n f i g u r a t i o n c a n i n f l u e n c e t h e degree o f o r i e n t i n g , a r e f o r m u l a t i o n o f t h e models w h i c h d i c h o t o m i z e v i s u a l l y g u i d e d b e h a v i o r i n t o two s e p a r a t e s y s t e m s , one c o n c e r n e d w i t h a n a l y s i n g t h e s p a t i a l c o n f i g u r a t i o n o f t h e s t i m u -l u s and a n o t h e r i n d e p e n d e n t s y s t e m c o n c e r n e d w i t h t h e i n i t i a t i o n ..of a n o r i e n t a t i o n r e s p o n s e , would be c a l l e d f o r . 19-EXPERIMENT I O r i e n t i n g t o " A p p a r e n t l y " M o v i n g and S t a t i o n a r y V i s u a l S t i m u l i . A c h a r a c t e r i s t i c o f v i s u a l s t i m u l i t h a t may he o f c o n s i d -e r a b l e i m p o r t a n c e i n e l i c i t i n g o r i e n t i n g f r o m an a n i m a l i s s t i m u l u s m o t i o n . T h i s d i m e n s i o n has a l s o been s u g g e s t e d as an i m p o r t a n t p a r a m e t e r w h i c h a f f e c t s t h e r e s p o n s e p r o p e r t i e s o f i n d i v i d u a l c e l l s o f t h e SC d i f f e r e n t l y f r o m t h o s e c e l l s i n t h e s t r i a t e c o r t e x . W h i l e we do n o t y e t have good e l e c t r o p h y s i o l o g i c a l e v i d e n c e i n t h e r a t , i n o t h e r mammalian s p e c i e s s u c h as t h e c a t and monkey, t h e c e l l s i n t h e s t r i a t e c o r t e x show a g r e a t d e a l o f p r e c i s i o n i n r e s -ponse t o t h e s t i m u l u s p a r a m e t e r s o f shape, o r i e n t a t i o n and c o l o u r and a r e l e s s p r e c i s e i n r e s p o n s e t o s t i m u l u s movement (Dow &:Gouras, 1973; H u b e l -..& W i e s e l , 1968). The SG c e l l s a r e n o t as r e s p o n s i v e t o o r i e n t a t i o n , shape, o r c o l o r , b u t a r e p r e c i s e l y t u n e d and s e l e c -t i v e t o t h e p o s i t i o n o f s t i m u l i and a r e r e s p o n s i v e t o s t i m u l u s movement. T h e i r f i r i n g r a t e i n c r e a s e s when eye movements a r e d i r e c -t e d towards t h e r e c e p t i v e f i e l d o f t h e c e l l s and t h e y r e s p o n d d i f f e r -e n t i a l l y t o : ( l ) movement o f a t a r g e t a g a i n s t a s t a t i o n a r y b a c k g r o u n d , (2) movement o f t h e t a r g e t c a u s e d by eye movements (Wurtz & M o h l e r , 1976) . The a r r a y o f a p p a r e n t l y moving ( a p p a r e n t l y moving t o t h e human o b s e r v e r ) o r s t a t i o n a r y b u t f l i c k e r i n g l i g h t s employed i n t h i s s t u d y a l l o w e d an assessment o f t h e i m p o r t a n c e o f t h i s s t i m u l u s dimen-s i o n i n e l i c i t i n g t h e o r i e n t i n g r e s p o n s e . The use o f t h e s e l i g h t s 2 0 also avoided the inclusion of other (e.g., auditory, somatic or sen-sory) cues which generally are confounded with visual cues when rats are tested i n situations i n which small, hand-held stimuli are used (Schneider, 19&7, 19&9)• ^ n addition, the animals i n the present study were not i n motion when the stimuli were presented , thus avoid-ing confusion between stimulus motion per se and stimulus movement produced by the animal's own movement. Previous research on orienting has often confounded these factors; for example, by incorporating running i n the discrimination test (Dyer et a l . , 1976; Goodale & Muirison, 1975; Goodale, Foreman, & Miner, 19-78). In reviewing the available evidence on the effect of par-ticular lesions on visually guided behavior, one thing i s clear: there i s considerable confusion as to what "orienting" i s and what constitutes evidence of i t s occurrence. In visual research the •: orienting response - generally has been conceived of as a unitary and reflexive behavior by which animals localize a visual stimulus i n space (but, see Lynn, 1966 for other conceptions of orienting). Consequently, i n tests of orienting the animal usually has been required to direct i t s activity towards a stimulus for a considerable amount of time to allow an investigator .to conclude that the animal has noticed, localized, and looked at the stimulus?. The o r i e n t i n g r e s -ponse, however, can be viewed as being comprised of a number of separate behavioral elements. These include: the cessation of ongoing behavior when a stimulus i s presented, the i n i t i a l saccadic eye and head movements to the generalllocation of the stimulus (localization), 2 I and perhaps finer eye and head position adjustments to accurately fixate the stimulus. In addition, the term "orienting" has been used to refer to a l l the reaching, tracking, following, and locomotor responses made towards visual stimuli (ingle & Sprague, 1975)- In the present study disruption of ongoing behavior i n response to the presentation of the light display was employed as the basic measure. The a b i l i t y to perform this element of orienting i s fundamental to the complete series of behaviors commonly defined as "the" orienting response. The following study attempted to determine i f lesioned animals were capable of the f i r s t and necessary phase of the orienting response to a large f i e l d novel visual stimulus. An attempt was made to produce lesions of the SC which were comparable i n size to those of other investigators whose data have been interpreted as suggesting that the SC i s necessary to visual orienting (Barnes et a l . 1 9 7 0 ; Dyer et a l . 1976; Schneider, I 9 6 7 , I 9 6 9 ) . Smaller SC lesions were also made to assess the involvement of the superficial and deep laminae of the SC i n the orienting response d e f i c i t . Striate cortex lesioned animals were employed both as controls for the non-specific cor t i c a l effects of the SC lesion procedure as well as to assess the possible involvement of the striate and extrastriate cortex i n orienting behavior. Method Subjects Forty naive male rats (Rattus Norvegicus) from the Long-Evans strain were obtained at approximately 200 g body weight from the Canadian Breeding Farms and Laboratories, Ltd., or reared i n the Biopsy-cology vivarium at the University of British Columbia. The type of lesion each animal received was determined randomly. The animals were housed i n groups of 4-8 animals in wire mesh cages (64 X 18 XI18 cm) and maintained on water and ad-lib food for at least 7 days prior to surgery and housed individually for 7 days following surgery (Tees, 1968, 1975). The colony lights were on a 12 hr. light, 12 hr. dark schedule and animals were tested between 1600 and 2400 hrs. Surgery A l l the animals were between 250-350 g at the time of surgery. A l l surgery was performed under sodium pentobarbital anes-thetic and supplemented with chloral hydrate when necessary (Pinel & Van Oot, 1977)- The following lesions were made. (a) Superior colliculus (SC) lesions were made stereotaxically i n 8 animals with a radio frequency lesion maker (Radionics model RFG4) using an electrode t i p exposure of 1 mm. The inter-aural line and upper edge of the incisor bar were in the horizontal plane. The electrode placements were made 1.8 mm on each side of the midline, 2.7 mm anterior to the most posterior aspect of the lambdoidal suture, and 3»7 mm below the cortical surface. The r f current was applied for 90 sec. „Tip temperature for these animals was 70°C. 2 3. (Adapted from Goodale ahd.J-Iuirisor., 1975) • • (b) Superficial colliculus laminar (SP) lesions were made i n 9 ani-mals. The tip's temperature varied "between 50°G and 60°C (one at 50oC, three at 55°C and four at 60°C). The stereotaxic coordinates were the same as those used for the SC group except that the elec-trode was only lowered to 3-5 mm below the cortical surface. (c) Deep superior colliculus laminar (DP) lesions were made i n 4 .animals. Electrode placement was identical to that described above except the electrode was lowered to 5 mm below the cortical surface. Tip temperature was 55°G for half the subjects and 60°G for the remaining half. (d) Striate cortex (ST) lesions were produced by aspiration i n 9 animals. The dorsal surface of the skull was removed for approxi-mately 2 mm behind bregma to lambda and from approximately 1 mm later a l to the sagittal suture to the zygoma. Suction was used to remove the exposed cort i c a l tissue under visual guidance (Tryggvason & Tees, 1 9 7 4 ) . An attempt was made to vary the .placement of the lesion to include area 17 'only, or area 17 , 18, a h d 18A (Kreig, 1946a,,1946b). (e) Sham operated controls (SH) were treated identically, however, no tissue was removed or current applied for these animals. There were a total of 10 sham operated animals. The striate cortex lesion procedure was used for 5 SH animals and the SG lesion procedure was used for the remaining 5 animals. Histology After completion of behavioral testing, operated animals 24. were perfused with .9% saline solution followed by 10% Formalin-saline . Brains were removed and placed i n 10% Formalin-saline. The brains of SP and DP lesioned animals were freeze, sectioned at 30 urn. Every f i f t h section was saved and stained with thionin. The SG and ST lesioned brains were either embedded i n gelatin and sectioned at 30 um or at 50 um. The extent of retrograde degeneration i n the dorsal lateral geniculate nucleus was examined for striate lesioned brains. These sections were stained with cresyl violet and luxol blue staining procedure. Every f i f t h section through the lesion and every second section through the thalamus was saved. Apparatus A diagram of the behavioral testing apparatus i s presented i n Figure 4. The box was housed i n a 66.2 X 66.0 X 50.8 cm outer light and sound attenuating box with a ventilation fan which produced a 60 dB masking noise. Nine 5-9 cm diameter lights covered by red plastic f i l t e r s were positioned 1?.8 cm from the t i p of the glass water spout, extending from the plexiglass wall. The entire display subtended approximately 98° of visual angle. The intensity of the lights measured at the water spout with a Weston light meter and recorded as approximately .6? cd/m for the set of 3 lights. The rat could be observed during the presentation of the light display through a 14.0 X 14.0 cm one-way viewing screen. Presentation of the lights and counting of the number of licks were automatically controlled by electro-mechanical counters and solid state (BRS/LVE) logic. 25 A. F i g u r e 4. The a p p a r a t u s u s e d t o examine d i s r u p t i o n o f l i c k i n g r e s p o n s e t o t h e p r e s e n t a t i o n o f t h e l i g h t d i s p l a y . P r o d e d u r e One week f o l l o w i n g s u r g e r y t h e r a t s were w a t e r d e p r i v e d f o r 48 h o u r s . E a c h r a t was t h e n a l l o w e d a c c e s s t o t h e w a t e r tube i n t h e a p p a r a t u s f o r 3 p r e t e s t d a y s . The number o f l i c k s was c o u n t e d f o r 15 m i n u t e s a f t e r t h e i n i t i a t i o n o f d r i n k i n g . The amount o f w a t e r consumed i n t h i s t i m e was s u f f i c i e n t t o m a i n t a i n a t l e a s t 9 0 f o body w e i g h t i n t h e m a j o r i t y o f a n i m a l s t e s t e d . A n i m a l s s u s t a i n i n g l e s i o n s t o t h e deep l a m i n a e o f t h e SG (DP l e s i o n e d a n i m a l s ) d i d n o t r e m a i n a t t h e i r p r e o p e r a t i v e w e i g h t u s i n g t h i s p r o c e d u r e . C o n s e q u e n t l y , t h e y were a l l o w e d an a d d i t i o n a l 15 m i n u t e s a c c e s s t o w a t e r i n t h e i r home cage f o l l o w i n g a d a p t a t i o n t o t h e box on p r e t e s t d a y s . T h i s p r o c e d u r e was s u f f i c i e n t t o m a i n t a i n 80^ -9Q?S body w e i g h t i n t h e s e a n i m a l s . On t h e f o u r t h day, d i s r u p t i o n o f l i c k i n g i n r e s p o n s e t o t h e p r e s e n t a t i o n o f t h e l i g h t d i s p l a y s , h a b i t u a t i o n , a n d d i s h a b i t u a t i o n o f t h i s r e s p o n s e were measured. On each t r i a l t h e e i g h t h l i c k made by th e a n i m a l i n i t i a t e d a b a s e l i n e p e r i o d o f 5 s e c d u r i n g w h i c h t h e num-b e r o f l i c k s were c o u n t e d . The e i g h t h l i c k made by t h e a n i m a l f o l l o w -i n g t h e b a s e l i n e p e r i o d i n i t i a t e d t h e l i g h t s , and t h e number o f l i c k s were c o u n t e d f o r 5 s e c ' ( A d a p t e d f r o m F i l e , 1973)- A l l t h e a n i m a l s were o b s e r v e d t h r o u g h t h e one-way v i e w i n g s c r e e n on t h e f i r s t t r i a l and some a n i m a l s were o b s e r v e d on a l l t h e t r i a l s i n t h e e n t i r e s e s s i o n . The f o l l o w i n g l i g h t d i s p l a y s were p r e s e n t e d i n t h e t e s t i n g s e s s i o n . ( S i ) " A p p a r e n t l y " moving l i g h t d i s p l a y , a t 1 p e r l / l O s e c . The f i r s t l i g h t d i s p l a y ( S i ) was a s e t o f " a p p a r e n t l y " moving l i g h t s . The f i r s t l i g h t on t h e r i g h t o f e a c h o f t h e t h r e e p a n e l s ( s e e F i g u r e 4) 2 7 was illuminated, for l/lO sec followed by each of the middle and then l e f t lights i n each panel with an interlight latency of l/lO sec. One light from each panel was illuminated to ensure that regardless of the direction of the animal's head one panel would always be within the visual f i e l d . The above display was presented for 15 t r i a l s . (52) Stationary-flickering display, at 1 per 1/10 sec. The right light of the right panel, the middle light, and the l e f t light of the l e f t panel were presented for l/lO sec with an interval of l/lO sec (i.e., three lights flickering every l/lO sec). Again, one light from each panel was illuminated. This display (S2) was presented on the l6th to 30th t r i a l . (53) "Apparently" moving display, at 1 per l/lO sec. The "apparently" moving lights described above were again presented, how-ever, the interlight interval and duration of the lights were changed to l/5 sec. This display (S3) was presented on the 31st to 35th t r i a l s . (54) Stationary-flickering, at 1 per 1/5 sec. The stationary display was presented with an interlight interval and light duration of l/5 sec. This display (S4) was presented on the 36th to 40th t r i a l . Data Presentation and Analysis Differences between the a b i l i t y of rats i n each of the groups to disrupt licking, habituate,.and dishabituate to the various light displays presented were assessed by analysis of variance. To f a c i l i t a t e data analysis and allow the use of available computer programs two separate analyses were conducted. The f i r s t assessed only the data from the f i r s t 5 t r i a l s for each light display 2 8. p r e s e n t e d ( S I , S2, S3, & S 4 ) . The ;second a n a l y s i s a s s e s s e d t h e d a t a f r o m t h e e n t i r e 15 t r i a l s p r e s e n t e d f o r each o f S i and S2. S t a t i s t i c a l r e l i a b i l i t y o f d i s r u p t i o n o f l i c k i n g i n r e s p o n s e t o t h e p r e s e n t a t i o n o f t h e l i g h t s was a s s e s s e d by c o m p a r i n g t h e num-b e r o f l i c k s i n t h e p r e c e d i n g b a s e l i n e p e r i o d w i t h t h e number o f l i c k s d u r i n g t h e p r e s e n t a t i o n o f t h e l i g h t s on each t r i a l by a p r i o r i t c o m p a r i s o n s . The c o m p a r i s o n s were b a s e d on t h e p a t t e r n X t r i a l X s t i m u l u s X group i n t e r a c t i o n e s t i m a t e of-, . v a r i a n c e and t h e degrees o f f r e e d o m a s s o c i a t e d w i t h - t h e G e i s s e r - G r e e n h o u s e c o n s e r v a t i v e e F t e s t s u g g e s t e d f o r r e p e a t e d measures d e s i g n s ( K i r k , 1968). The SG, SP, DP, and ST l e s i o n e d a n i m a l s were compared t o t h e SH c o n t r o l a n i m a l s by D u n n e t t ' s m u l t i p l e c o m p a r i s o n p r o c e d u r e b a s e d on t h e groups X t r i a l X s t i m u l u s i n t e r a c t i o n e s t i m a t e o f v a r i a n c e . T h i s a n a l y s i s a s s e s s e d d i f f e r e n c e s between t h e l e s i o n e d a n i m a l s and c o n t r o l s i n amount o f d i s r u p t i o n o f l i c k i n g d u r i n g t h e p r e s e n t a t i o n o f s t i m u l u s d i s p l a y s and d i f f e r e n c e s i n amount o f b a s e l i n e l i c k i n g . The a n a l y s i s o f t h e e n t i r e 15 t r i a l s f o r e a c h o f S I and S2 was s u p p l e m e n t e d by a p r i o r i t t e s t s and D u n n e t t ' s t e s t as d e s c r i b e d above. T h i s a n a l y s i s a l l o w e d a s e p a r a t e assessment o f t h e e n t i r e number of t r i a l s on w h i c h t h e a n i m a l s r e l i a b l y d i s r u p t e d l i c k i n g i n r e s p o n s e t o S i and S2 f o r each o f t h e l e s i o n e d g r o u p s . Results The results of the analysis of variance which compared the lesioned animals on the f i r s t 5 t r i a l s i n response to the four light,1; displays are presented i n Table 1 of Appendix A•and those of the anal-sis- ©f- -variance which included" the-entire-. -1"5" t r i a l s i n which S.I and.S2 were presented are included, as • Table 2-of .Appendix'rA. The SG, SP, and DP animals differed markedly from the SH animals and each other i n terms of disruption of licking i n response to the lights, habituation, and dishabituation. The results are presented for the SH and each of the lesioned groups i n Figure 5(a-e), and wi l l be discussed separately below. Sham lesions (SH) Behavioral results. The presentation of SI, the apparently moving lights, resulted i n marked disruption of licking by the SH animals on the f i r s t t r i a l . Photographs of a video-taped recording of a representative shamllesioned animal are presented i n Figure 6. They i l l u s t r a t e the orienting and body movements e l i c i t e d by this light display which are not compatible with maintaining contact with the water spout. Repeated presentation of the apparently moving light display resulted i n a waning.of this response (habituation) and eventually the animals drank thoughout the entire 5 sec presen-tation of the lights. Disruption of licking was reliably different from baseline on the f i r s t 5 t r i a l s i n response to SI (t, << = .05/2 = 6.66, df = 30). The SH animals reliably disrupted licking on the f i r s t t r i a l when the light display was changed (dishabituation). 30 A. F i g u r e 5(a-e). Mean number o f l i c k s p e r 5 sec d u r i n g b a s e - -l i n e (B) and d u r i n g t h e p r e s e n t a t i o n o f t h e s t i m u l u s ( S ) , f o r l i g h t d i s p l a y s S I , S2, S3, and Sk. ( a ) SH, (b) ST, ( c ) SG, (d) SP, and ( e ) DP l e s i o n e d a n i m a l s . The a s t e r i s k i n d i c a t e s t h e t r i a l s on w h i c h d i s r u p t i o n o f l i c k i n g was s t a t i s t i c a l l y r e l i a b l e . •-& GROUP DP N - 4 5 o 3 . M e a GROUP SP N • 9 6 B S i N u m b e r o f Licks per 5 Se . GROUP SC N - 8 3 3 S c. GROUP ST. N - 9 5 3 S GROUP SH N - 10 S SS 8 S 1 1 1 1 1 1 1 1 1 1 1 1 1 1 • 1 1 1 1 1 1 1 / • :• v * :• . V I ' :\ . / : : / :' 7 \ : ' \ i i i i i :. 1 i i 1 1 i i i : / • ' i i i i i i i : / I I I.I 1 1 1 1 : .1 : ^ : ... i : / : / : • 7 : / • / . : / • \ : /• : • / • -** / / . / • : / . i i i i i i i : \ i i i i i i i : . / i i i i i i i : l I I : \ : 1 : • - '/• : \ : / : • / : / : / \ : / : \ : • y : I : / ' : / : / : I : . 1 i i i i i i i \ :• I : I i i i i i i i : . \ : / : l :• • I : / . :. / : x \ : / . : l : / :•• • / : 1 : I : • .1 . : /• / 31 A. F i g u r e 6. P h o t o g r a p h s f r o m v i d e o t a p e d r e c o r d i n g s o f the. r e s -ponses" of. r e p r e s e n t a t i v e a n i m a l s t o t h e l i g h t d i s p l a y on t h e f i r s t t r i a l s ( a ) an SH c o n t r o l a n i m a l ' s d r i n k i n g when the l i g h t s f i r s t come on, ( h ) i t s head and p o s t u r a l a d j u s t m e n t s a n d ( c ) and ( d ) i t s f u r t h e r e x p l o r a t o r y b e h a v i o r , ( e ) , ( f ) , and ( g ) , a n SG l e s i o n e d a n i m a l d r i n k i n g t h o u g h o u t t h e e n t i r e t r i a l . 31 B. 31 C. 31 E. (g) Trials on which licking was reliably different from "baseline for the entire session are marked by an asterisk i n Figure 5(a). Superior Colliculus Lesions (SC) Behavioral results. Animals with large lesions of theSC including the superficial and deep lamina did not reliably disrupt licking i n response to the presentation of any of-the light displays. As can be see i n Figure 5(c), small differences between licking during baseline andl during the' presentation' of the light? display for these animals were not s t a t i s t i c a l l y reliable ( t , ° i = .05/2, = 6.66, df = 30). On the third presentation of the light display S4, (i.e., the 38th t r i a l ) , however, some of these animals did respond to the presen-tation of the stimulus. The number of licks made during baseline was very similar to control animals' and did not d i f f e r s t a t i s t i c a l l y (Dunnett's t, = .05/2, 5, 30 = 8.96). Anatomical results. The extent of the lesions sustained by this group of animals i s depicted i n Figure ?(a). The largest and smallest lesions at each of 5 representative levels of the SC are presented. The lesions extended into the pretectal nuclei, overlying white matter of the cortex, hippocampus, central grey, tegmentum,and, i n two cases, the posterior thalamic .•nuclei. The dorsal tegmentum and central grey were always included i n this lesion. A l l the animals i n this group sustained a large lesion i n the medial portion of the SC, including a l l 7 laminae, the posterior aspect of branchium of the superior colliculus, the dorsal surface of the teg-mentum, and touched on the central grey. 3 3 . B e h a v i o r a l - a n a t o m i c a l r e l a t i o n s h i p s ' . The SG l e s i o n s v a r i e d p r i m a r i l y i n t h e a n t e r i o r - p o s t e r i o r p l a n e . The e x t e n t o f t h e dam-age was, however, c o n s i s t e n t i n t h e c e n t r a l p o r t i o n o f t h e SC l e s i o n ( r e p r e s e n t e d by t h e m i d d l e s e c t i o n i n F i g u r e . 7 ( A ) ) . F o u r a n i m a l s had more a n t e r i o r l y p l a c e d l e s i o n s w h i c h i n c l u d e d e x t e n s i v e damage o f t h e p r e t e c t u m and hippocampus w h i l e t h e r e m a i n i n g 4 l e s i o n s were more p o s t e r i o r and r e s u l t e d i n c o n s i d e r a b l e damage t o the o v e r -l y i n g c o r t i c a l w h i t e m a t t e r and i n f e r i o r c o l l i c u l i . Two a n i m a l s w i t h p o s t e r i o r l y p l a c e d l e s i o n s and 1. a n i m a l : w i t h a more a n t e r i o r l e s i o n d i s r u p t e d l i c k i n g b y a t l e a s t h a l f t h e amount o f t h e p r e c e d i n g b a s e l i n e p e r i o d on the f i r s t t r i a l . None o f the o t h e r a n i m a l s r e s - " ponded t o t h e l i g h t d i s p l a y s t o t h i s e x t e n t on t h e f i r s t o r any o t h e r t r i a l . The h i s t o l o g i c a l r e s u l t s and b e h a v i o r a l d a t a f o r 2 a n i m a l s w i t h p o s t e r i o r l y p l a c e d l e s i o n s and 1 animal'- w i t h ar v e r y l a r g e - and a n t e r i o r l y p l a c e d l e s i o n a r e p r e s e n t e d i n F i g u r e 8 ( a - c ) . Of i n t e r e s t i n t h i s f i g u r e i s t h e absence o f an o b v i o u s r e l a t i o n s h i p between t h e p l a c e m e n t , s i z e , a n d . i n c l u s i o n o f ^ a d j a c e n t s t r u c t u r e s i n t h e l e s i o n and t h e p r e s e n c e o r absence o f r e s p o n d i n g t o t h e l i g h t d i s p l a y on t h e f i r s t t r i a l . S u p e r f i c i a l L a m i n a r L e s i o n s o f t h e S u p e r i o r C o l l i c u l u s ( S P ) B e h a v i o r a l r e s u l t s . R a t s w i t h s m a l l l e s i o n s r e s t r i c t e d p r i m a r i l y t o t h e s u p e r f i c i a l l a m i n a e o f t h e s u p e r i o r c o l l i c u l u s d i f f e r e d from-.the SC l e s i o n e d a n i m a l s d e s c r i b e d -above. They d i s -r u p t e d l i c k i n g when l i g h t d i s p l a y S I was p r e s e n t e d on t h e f i r s t 34 A. Figure 7(A-D). .Representative-sections depicting :the extent of damage to SG and surrounding tissue for (A) SG, (B) SP, (G) DP, and (D) a surface view of cortical damage and corresponding thala-mic degeneration. The smallest lesion at each representative section i s drawn i n black and the largest i s stippled. 34 B. 35 A. Figure 8(a-c). Histological reconstructions and behavioral results for individual SG lesioned animals: (a) SG"#22 had a more posterior lesion, (h) SG #24 had a more posterior lesion, (c) SG #20 had a large anterior lesion. t r i a l as can be seen i n Figure 5(d-). They required fewer t r i a l s to habituate to the repeated presentation of the lights than the SH animals, however, and did not dishabituate to any of the stimulus changes presented. Disruption of lic k i n g i n response to presentation ' of the lights was s t a t i s t i c a l l y reliable (t, »4 = .05/2, = 6.66, df -30) on only the f i r s t 2 t r i a l s (marked by asterisks i n Figure 5<i) • SP animals did not diff e r s t a t i s t i c a l l y from SH animals i n amount of licking during baseline (Dunnett's t, <* = -5, 30 = 8.96). Anatomical results. The results of the damage to the superficial laminae of the SC and the surrounding tissue sustained by this group of animals i s presented in-Figure 7(B). The.largest and smallest lesions at each level of the representative coronal sections are presented. The lesions sustained by SP animals were restricted "primarily" to the superficial lamina of SC, with minimal involve-ment of the pretectal nuclei and minimal, but some, damage to the deep SC -laminae and occasionally the dorsal tegmentum. The lesions were restricted either to the anterior SC and pretectal nuclei or the posterior SC and posterior tegmentum but never both. Behavioral-anatomical relationships. .. The- histological - and behavioral results for representative animals with anterior or' poster-i o r SP lesions are presented i n Figure 9(A-B). As can be seen, the behavioral results are quite similar for. these two animals i n spite of the variation i n anterior-posterior placement of. the lesions. The damage to both subjects coincides i n the middle of the SC (repre-sented by the middle section i n Figure 7(B). A l l subjects with 37 A. F i g u r e 9 ( a - c ) . H i s t o l o g i c a l r e c o n s t r u c t i o n s and b e h a v i o r a l r e s u l t s f o r i n d i v i d u a l SP l e s i o n e d a n i m a l s : (a) SP #35 has an a n t e r i o r p l a c e d l e s i o n , (b) SP #28 has a p o s t e r i o r p l a c e d l e s i o n a n d ( c ) DP #8. 3 8. damage to this region of the SC behaved i n a fashion typical of the SP lesion group and depicted by the averaged data i n Figure 5(d.) • Deep laminar Lesions of the Superior Colliculus (DP) Behavioral results. Rats with very small lesions restricted primarily to the deep: laminae of the superior "colliculus behaved like-the SC lesioned-animals and/did.'not"respond to the presentation of the light displays. The results for this group of animals are presented i n Figure 5(e)- S t a t i s t i c a l l y reliable (t, oe- = '05/2 = 6.66, df = 30) disruption of licking i n response to the presentation of the light displays only occurred on the third t r i a l to the fourth stimulus display (i.e., the 38th t r i a l ) . Licking during the baseline measures did not d i f f e r s t a t i s t i c a l l y from SH; animals (Dunnett's t, <*. = .05/2, 5» 30 = 8.96) on any t r i a l . Anatomical results. The extent of lesions of the DP lesioned animals at four representative levels are presented i n Figure 7(C). As can be seen i n this figure these lesions are much smaller and restricted to the deep laminae-.of the SC and to the-dorsal surface of the tegmentum. In none of the rats were the pretectal nuclei or branchium of the SC involved i n the lesion. Damage to the central grey was, i n two cases, extensive but much less than i n the SC lesioned animals. . In one case (DP#8), central grey was not involved at any level. This animal's histology and behavioral data are presented i n Figure 9(c). Behavioral-anatomical relationships. A l l the animals i n this group had similarly placed lesions and the behavioral data were markedly similar such that DP #8 i s representative of this group. Striate Cortex lesions (ST) Behavioral results. Striate lesioned animals did not di f f e r from SH lesioned animals. They reliably disrupted licking i n response to the presentation of the light display, habituated, and 'dishabituated to each of the light displays-. The t r i a l s on which s t a t i s t i c a l l y reliable disruption of licking i n response to the light displays occurred (t, = .05/2 = 6.66, df = 30) are marked by an asterisk i n Figure 5(b). Disruption of licking i n response to the presentation of light display SI was s t a t i s t i c a l l y reliable• on the f i r s t 6 t r i a l s , to S2 on the f i r s t 4 trials,--to S3 on. the f i r s t . 2 t r i a l s , and to S4.on the f i r s t t r i a l . None of the small differences between the • SH•and ST animals for the baseline l i c k i n g or during the presentation of the lights approached s t a t i s t i c a l significance. Anatomical results. The extent of the damage to the cor-tex sustained by this group i s depicted i n Figure 7(D). The small-est and the largest lesion included i n this, group are presented i n a surface drawing and the extent of associated LGN degeneration at three representative levels i s also presented. Behavioral-anatomical relationships. Examples of a large ST lesion that included areas 17, 18, and 18A and t h e ' S m a l l e s t lesion that was restricted primarily to area 17 are presented i n Figure 10(a-b). The behavioral results for each of these animals are also included. These examples clearly i l l u s t r a t e that striate cortex-or 40 A. Figure 10(a-c). Histological and behavioral results for individual ST lesioned animals: (a) ST #3 has a large cortical lesion including areas 17, 18 and 18A, (b) ST #22 has a small cor-t i c a l lesion confined to area 17, (c) ST #7 has a large cortical lesion which included areas 17, 18, 18A and 7-4 1-striate cortex plus extrastriate cortex are not essential for the disruption of licking i n response to visual stimuli. Also included i n Figure 10 are the anatomical and behavioral results f o r ST #7. This animal's data were included as, interestingly, i t behaved like the SC and DP lesioned animals (i.e., i t did not disrupt licking i n response to any of the light displays i n the entire testing session) While the animal's cortical histology does not appear markedly different from other animals i n this group who sustained large cor-t i c a l lesions, the lesion clearly included a l l of areas 17, 18, 18A , and area 7« The other animals, had as large lesions of the cortex, but the lesions did not always remove a l l of area 7 and the posterior cortex. 4 2/ D i s c u s s i o n O v e r a l l , t h e r e s u l t s o f t h i s i n i t i a l s t u d y seem t o s u p p o r t S c h n e i d e r ' s two s y s t e m h y p o t h e s i s . The g e n i c u l o - s t r i a t e s y s t e m i s n o t i n v o l v e d i n t h e o r i e n t i n g r e s p o n s e . O r i e n t i n g can,, i n f a c t , be i d e n t i f i e d w i t h t h e t e c t a l s y s t e m i n t h a t r e m o v a l o f SG r e s u l t e d i n t h e absence o f o r i e n t i n g t o even moving and s t a t i o n a r y s t i m u l i p r e s e n -t e d t h r o u g h o u t a l a r g e f i e l d . I n a d d i t i o n , i t a p p e a r s f r o m t h e s e r e s u l t s t h a t t h i s b a s i c component o f o r i e n t i n g c a n be b e t t e r a s s o c i a -t e d w i t h o n l y t h e deep l a m i n a e o f t h e m e d i a l p o r t i o n o f SC and t h e s u r f a c e o f t h e d o r s a l tegmentum. L e s i o n s r e s t r i c t e d t o t h e more s u p e r f i c i a l l a m i n a e o f SG d i d n o t i m p a i r o r i e n t i n g t o t h e n o v e l v i s u a l s t i m u l u s . A s i m i l a r f i n d i n g has been r e p o r t e d by Casagrande and Diamond (197*0. L e s i o n s o f SC i n t r e e shrews o n l y i m p a i r e d o r i e n t i n g t o v i s u a l s t i m u l i and a v o i d a n c e o f t h r e a t e n i n g s t i m u l i i f t h e deep l a m i n a e o f SC were i n c l u d e d i n t h e l e s i o n . These r e s u l t s have been i n t e r p r e t e d as i n d i c a t i n g t h a t t h e SG i s , i n f a c t , two f u n c t i o n a l l y s e p a r a b l e s t r u c t u r e s ( i n g l e & Sprague, 1975). A c l o s e r e x a m i n a t i o n o f t h e l e s i o n - b e h a v i o r d a t a i n d i c a t e s t h a t a number o f q u a l i f y i n g s t a t e m e n t s must be added t o t h i s s u p e r -f i c i a l a n a l y s i s o f t h e r e s u l t s . One w o u l d e x p e c t t h a t i f s p e c i f i c s t r u c t u r e s were e s s e n t i a l f o r t h e o c c u r r e n c e o f a r e s p o n s e , t h e n t h e r e m o v a l o f t h i s s t r u c t u r e w o u l d a l w a y s e l i m i n a t e t h e r e s p o n s e . T h i s d i d n o t a p p e a r t o be t h e c a s e i n t h e p r e s e n t s t u d y . L e s i o n s i z e and p l a c e m e n t were g e n e r a l l y p r e d i c t i v e o f t h e a n i m a l ' s b e h a v i o r ; however, t h e y were n o t p e r f e c t l y s o . S i x a n i m a l s i n t h i s s t u d y d i d n o t behave 4 3.. i n a manner t y p i c a l o f t h e l e s i o n group t o w h i c h t h e y b e l o n g e d ( l i n t h e ST g r o u p , 2 i n the SP group, and 3. i n t h e SC g r o u p ) . W h i l e i t i s i m p o r t a n t n o t t o o v e r i n t e r p r e t t h e "misbehav-i o r " o f a few members o f t h e group, t h e s e a n i m a l s do p r o v i d e a d d i -t i o n a l d a t a t h a t a r e n o t r e p r e s e n t e d by a v e r a g e d r e s u l t s . F i v e o f t h e a n i m a l s (2 w i t h SP l e s i o n s , 3 w i t h SC l e s i o n s ) d i s r u p t e d l i c k i n g i n t h e p r e s e n c e o f t h e l i g h t s on t h e f i r s t t r i a l s , when i n f a c t t h e i r h i s t o l o g i c a l r e s u l t s w o u l d i n d i c a t e t h a t t h e y w o u l d have b e e n i n c a p a b l e o f o r i e n t i n g i f t h e SC were e s s e n t i a l . I n t h e p a r a -digm u s e d i n t h i s s t u d y , i t i s p o s s i b l e t h a t t h e a n i m a l s may have d i s r u p t e d l i c k i n g on t h e s e p a r t i c u l a r t r i a l s f o r r e a s o n s n o t r e l a t e d t o t h e appearance o f t h e l i g h t s ; however, t h e e x p e r i m e n t e r d i d o b s e r v e t h e r a t s on t h e f i r s t t r i a l o f t h e s e s s i o n . I n t h r e e o u t o f t h e f i v e c a s e s i n q u e s t i o n she o b s e r v e d head and body movements w h i c h were s i m i l a r t o t h o s e o f SH a n i m a l s , a l t h o u g h n o t as d r a m a t i c , and c o n -c l u d e d t h a t t h e s e t h r e e a n i m a l s had l o o k e d a t t h e l i g h t s . EXPERIMENT I I O r i e n t i n g t o an A u d i t o r y S t i m u l u s . T h i s s t u d y was c o n d u c t e d t o d e t e r m i n e i f SG and ST l e s i o n e d a n i m a l s were c a p a b l e o f d i s r u p t i n g l i c k i n g i n r e s p o n s e t o a u d i t o r y s t i m u l i . I t i s p o s s i b l e t h a t t h e i m p a i r m e n t o f o r i e n t i n g d e m o n s t r a t e d by SC l e s i o n e d a n i m a l s i n t h e p r e c e d i n g s t u d y was due t o a g e n e r a l i z e d motor i m p a i r m e n t o r i n a b i l i t y t o w i t h h o l d a r e s -ponse s u c h as l i c k i n g u n d e r c o n d i t i o n s o f w a t e r d e p r i v a t i o n ( W i n t e r -k o r n , 1976). Some s u p p o r t f o r t h i s p r o p o s i t i o n i s p r o v i d e d by K i r v e l e t a l ' . s . (1974) f i n d i n g t h a t SC l e s i o n e d r a t s had b e h a v i o r a l d e f i -c i t s i n o r i e n t i n g t o and l o c a l i z i n g o l f a c t o r y and s o m e s t h e t i c s t i m u l i e q u i v a l e n t t o t h a t f o u n d w i t h r e s p e c t t o v i s u a l s t i m u l i . Goodale and M u i r i s o n (1975) a l s o r e p o r t t h a t SC l e s i o n e d a n i m a l s were n o t d i s t r a c t e d by tone c l i c k s and f l a s h i n g l i g h t s p r e s e n t e d i n t h e p e r i -p h e r a l f i e l d . A l t h o u g h comparable d a t a f o r r a t s a r e n o t a v a i l a b l e , D r a g e r and Hu b e l (1976) and W i c k e l g r e n and S t e r l i n g (1969) r e p o r t t h a t i n d i v i d u a l c e l l s o f t h e deep l a m i n a e o f t h e SC r e s p o n d e d t o c o m b i n a t i o n s o f a u d i t o r y , s o m e s t h e t i c and v i s u a l s t i m u l i ( i . e . , were m u l t i m o d a l ) i n b o t h mice and c a t s . I n t h i s s t u d y v e r y s a l i e n t a u d i t o r y t o n e s were u s e d and the a u d i t o r y s t i m u l i were n o t a s s o c i a t e d w i t h c o n c u r r e n t o l f a c t o r y , s o m e s t h e t i c , and v i s u a l s t i m u l i . I n a d d i t i o n , t h e a n i m a l s were n o t r e q u i r e d t o l o c a l i z e and d i r e c t a c t i v i t y t owards t h e a u d i t o r y s t i m u l i . I n t h e s e ways t h e p a r a d i g m employed r e p r e s e n t s a b e t t e r t e s t o f t h e 45. SC and ST l e s i o n e d a n i m a l s ' a b i l i t y t o d i s r u p t l i c k i n g i n r e s p o n s e t o an a u d i t o r y s t i m u l u s t h a n t h o s e u s e d p r e v i o u s l y . Method Subjects " The 80 animals previously tested i n Experiment I and III were subje'cts..: - - - • - • Apparatus A 38 X 30 X 27 cm plexiglass box was housed i n the outer sound and light attenuating box used i n the previous study. A sona-l e r t on one side of the plexiglass box produced a 4500 Hz, 80 dB tone, while a second on the other side of the box produced a 2800 Hz, 80 dB tone. Presentation of the tones and counting of the number of licks were controlled by electromechanical counters and so l i d state (BRS/LVE) logic. Procedure The procedure was identical to that of Experiment I, except that tones were presented rather than the light displays (adapted from F i l e , 1973)- The rats were allowed access to the water spout i n the auditory testing apparatus on the two days f o l -lowing visual testing, for 15 min of drinking. On the next day, tests of disruption, habituation, and dishabituation to the .audi-tory stimuli were conducted. The procedure was identical to the visual testing, except that a 4500 Hz, 80 dB tone pulsed at a rate of 1 per 1/10 sec was presented on the f i r s t 5 t r i a l s . On t r i a l s 6-10, the 4500 Hz tone pulsed at a rate of 1 per l/5 sec. The 2800 Hz tone was then presented on the 11th-15th t r i a l . R e s u l t s A l l t h e l e s i o n e d and SH a n i m a l s r e l i a b l y d i s r u p t e d l i c k i n g i n r e s p o n s e t o t h e p r e s e n t a t i o n o f t h e t o n e s , h a b i t u a t e d t o t h e i r r e p e a t e d p r e s e n t a t i o n , and d i s h a b i t u a t e d t o t h e changes f r o m one tone t o a n o t h e r . The r e s u l t s a r e presented'* i n F i g u r e 11 f o r each o f th e l e s i o n e d and SH groups o f a n i m a l s . The r e s u l t s o f t h e a n a l y s i s o f v a r i a n c e a r e p r e s e n t e d i n T a b l e 3 o f Appendix A. T r i a l s on wh i c h d i s r u p t i o n o f l i c k i n g i n r e s p o n s e t o t h e tone were r e l i a b l y d i f f e r e n t f r o m b a s e l i n e d r i n k i n g a r e marked by an a s t e r i s k i n F i g u r e 11 ( t , en = .05/2, = 4.96, d f = 60). The SH, ST, SG, SP, and DP l e s i o n e d a n i m a l s r e l i a b l y d i s r u p -t e d l i c k i n g on a t l e a s t t h e f i r s t t r i a l when t h e l / l O s e c p u l s e d 4500 Hz t o n e was p r e s e n t e d and began t o h a b i t u a t e o v e r t h e n e x t f o u r t r i a l s . A l l t h e l e s i o n e d and SH a n i m a l s d i s h a b i t u a t e d t o t h e change i n t h e p u l s e r a t e o f 4500 Hz tone f r o m 1 p e r l / l O sec t o 1 p e r l/5 s e c ; however, t h e a n i m a l s were much more r e s p o n s i v e t o t h e change i n f r e q u e n c y f r o m the 4500 Hz tone t o t h e 2800 Hz t o n e . None o f t h e s m a l l d i f f e r e n c e s i n l i c k i n g d u r i n g t h e b a s e l i n e o r d u r i n g t h e p r e s e n t a t i o n o f t h e t o n e s was r e l i a b l e . 48 A. F i g u r e 11. Mean number o f l i c k s p e r 5 s © c d u r i n g t h e b a s e l i n e (B) and d u r i n g t h e p r e s e n t a t i o n o f t h e a u d i t o r y tone (S) f o r : ( a ) SH, (b) ST, ( c ) SC, ( d ) SP and ( e ) DP l e s i o n e d a n i m a l s . The a s t e r i s k i n d i c a t e s t h e t r i a l s on w h i c h d i s r u p t i o n o f l i c k i n g was- s t a t i s t i c a l l y r e l i a b l e . • - * Discussion The results of this study clearly demonstrate that lesions of SC do not result i n a general impairment of the a b i l i t y to disrupt ongoing behavior. In addition, they demonstrate the capacity of the lesioned animals to habituate to the repeated presentation and disha-bituate to even subtle changes within another modality. Winterkorn, (1976) has suggested that lesions of SC i n cat result i n an i n a b i l i t y to disrupt ongoing behavior i n response to changes i n a stimulus and argued for a generalized attentive impairment. This i s clearly not the case for the rat. (Although differences between SC lesioned and control animals might be observed i f stimuli closer to threshold were employed.) Direct observation of the animals on the f i r s t t r i a l f o r each of the three tones presented demonstrated that they were capable of the apprpriate head and body movements necessary to localize an auditory stimulus. A l l the rats i n this experiment l i f t e d their heads and turned their bodies i n the direction of the sonalert on at least the f i r s t t r i a l i n response to the 4500 Hz, 1 per 1/10 sec pulsed tone and i n response to the 2800 Hz tone. Some of the animals approached the sonalerts and reared and sniffed them,"but no SC lesioned animals were observed to engage i n this activity. These findings are somewhat at odds with studies that report multimodal sensory neglect by SC lesioned animals (Goodale & Muirison, 1975; Kirvel et a l . , 1974). A possible explanation may be differences i n the paradigms employed. The shoulder hold used by Kirvel et a l . may have induced more struggling i n the SC lesioned animals. These animals were required to localize and make a head turn i n the direction of the stimulus to be judged to have oriented. This i s a response even the normal animal i s unlikely to make as lateral head movements are not usually made independent of changes i n body position for this species (Drager & Hubel, 1975)- Changes i n body position would have been restrained by the shoulder hold. The measure used by Goodale and Muirison may also have been less sen-si t i v e to the disruption of ongoing behavior by SC lesioned animals i n response to the auditory stimuli, particularly since these animals do not display the intense exploratory activity observed for the SH control animals i n the present study. Experiment I demonstrated an impairment i n the a b i l i t y of SC lesioned animals to disrupt licking i n response to the presentation of a visual stimulus. The second study suggests that the impairment i n response to the lights can not be attributed to a general i n a b i l i t y to disrupt behavior or an i n a b i l i t y to make the appropriate head and postural adjustments necessary to localize a stimulus. 51. EXPERIMENT III The Effect of Increasing the Intensity of the Lights on Orienting to "Apparently" Moving and Stationary Light Displays. The results of Experiments I.and II suggested that the SC i s l i k e l y involved i n some aspect of orienting to visual stimuli. However, the fact that i n Experiment I some SC lesioned animals did orient to the light display on the f i r s t t r i a l implied that the SC lesions may not entirely eliminate the'-orienting. response... Moreover, the d e f i c i t i n orienting that did occur could not he attributed to a general i n a b i l i t y to make the kind of response required i.e., to disrupt licking behavior or to make appropriate head and postural adjustments necessary to localize a stimulus. I t i s s t i l l possible, however,- that a l l " the SC lesioned' animals were s t i l l capable of orienting to the lights, but were simply less l i k e l y to. Although the light displays employed in Experiment I were extremely effective i n e l i c i t i n g orienting for SH operated animals, perhaps the impact of this light display was insufficient to e l i c i t orienting from the SC lesioned animals. A number of stimulus dimen-sions besides motion could influence the magnitude of the' orienting response and the ease with which i t i s e l i c i t e d . The following study attempted to examine the influence of increasing the physical inten-s i t y of the lig h t display to determine i f this stimulus characteris-t i c would f a c i l i t a t e orienting by the SH and SC lesioned animals. 5 2. Method S u b j e c t s F o r t y n a i v e male r a t s were o b t a i n e d , f r o m t h e C a n a d i a n B r e e d i n g Farms and L a b o r a t o r i e s L t d . o r r e a r e d i n t h e B i o -p s y c h o l o g y v i v a r i u m a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a . A n i m a l maintenance and s u r g e r y were i d e n t i c a l t o t h a t d e s c r i b e d i n E x p e r i -ment I . A t o t a l o f 9 SH, 8 SC, 9 SP, 10 ST,, and 4 DP l e s i o n e d a n i -mals were t e s t e d . A p p a r a t u s The t e s t i n g a p p a r a t u s was i d e n t i c a l t o t h a t d e s c r i b e d i n E x p e r i m e n t I * The i n t e n s i t y o f t h e l i g h t s r e c o r d e d a t t h e w a t e r 2 2 s p o u t was 5'25 cd/m as compared t o .6? cd/m i n E x p e r i m e n t I . The i n t e n s i t y o f t h e l i g h t s was i n c r e a s e d i n t h i s s t u d y by r e m o v i n g t h e r e d p l a s t i c f i l t e r s f r o m e a c h o f t h e 9 l i g h t s i n t h e l i g h t d i s p l a y . P r o c e d u r e The p r o c e d u r e was i d e n t i c a l t o t h a t d e s c r i b e d i n E x p e r i m e n t I . Results The results of the analysis of variance which compared the lesioned animals on the f i r s t 5 t r i a l s for each of the four light displays are presented i n Table 4 of Appendix A. Results of the analysis of variance which included the entire 15 t r i a l s in which SI and S 2 were presented are included as Table 5 of Appendix A. The results of this study are presented in Figure 12(a-e) for each of the lesion "groups' and are discussed separately below. Sham Xeslons (SH) Behavioral results. The sham lesioned animals reliably disrupted licking i n response to the presentation of the four lig h t displays. Trials on which the animals reliably disrupted licking i n response to the presentation of the lig h t displays are marked by an asterisk in Figure 1 2(a). Disruption of licking i n response to the N presentation of SI was marked on t r i a l s 1-3 but began to wane on the fourth and f i f t h t r i a l s as the animals habituated to the repeated presentation of the light displays. The SH animals in this study reliably disrupted licking on the f i r s t 6- t r i a l s to the .light dis-play SI, and oh the f i r s t 3 t r i a l s to each of the light "displays ; S 2 , S3, and S 4 (t, * = .05/2 = 5.89, df = 30). Dishabituation reliably occurred to each change from one light display to another for these animals. Superior Colliculus Lesions (SC) Behavioral results. Rats with large lesions which included the superficial and deep laminae of the SC reliably disrupted licking i n r e s p o n s e t o t h e p r e s e n t a t i o n o f t h e l i g h t d i s p l a y ( S i ) i n t h i s s t u d y . U n l i k e t h e r e s u l t s f o r t h i s group i n E x p e r i m e n t I , i n w h i c h o n l y 3 SC l e s i o n e d a n i m a l s l o o k e d a t t h e l i g h t d i s p l a y on t h e f i r s t t r i a l , a l l t h e SC l e s i o n e d a n i m a l s a p p e a r e d t o l o o k a t t h e l i g h t d i s p l a y i n t h i s s t u d y . A l l h u t 2 o f t h e SC l e s i o n e d a n i m a l s d i s r u p t e d l i c k i n g by a t l e a s t h a l f t h e b a s e l i n e number o f l i c k s on the f i r s t t r i a l i n r e s p o n s e t o l i g h t d i s p l a y S I . A l l t h e a n i m a l s were o b s e r v e d t o l i f t t h e i r heads f r o m t h e w a t e r s p o u t and a p p e a r e d t o l o o k a t t h e l i g h t s on t h i s t r i a l . U n l i k e t h e SH a n i m a l s , however, SC a n i m a l s i n v a r i a b l y resumed l i c k i n g w i t h i n the 5 s e c p e r i o d o f exposure t o t h e l i g h t s and d i d n o t make any o b s e r v a b l e p o s t u r a l changes o t h e r t h a n t h e head and u p p e r body movements d e s c r i b e d . W h i l e t h e SC l e s i o n e d a n i m a l s d i s r u p t e d l i c k i n g a nd a p p e a r e d t o l o o k a t t h e l i g h t d i s p l a y when p r e s e n t e d on t h e f i r s t t r i a l , t h e s e a n i m a l s h a b i t u a t e d more q u i c k l y t o t h e r e p e a t e d p r e s e n t a t i o n o f t h e l i g h t s t h a n t h e SH a n i m a l s . D i s r u p t i o n o f l i c k i n g d u r i n g t h e p r e s e n -t a t i o n o f S I was o n l y r e l i a b l y d i f f e r e n t f r o m b a s e l i n e on the f i r s t t r i a l , w h i l e SH a n i m a l s r e l i a b l y d i s r u p t e d l i c k i n g on t h e f i r s t s i x t r i a l s i n r e s p o n s e t o t h e p r e s e n t a t i o n o f S I . A l s o , t h e SC l e s i o n e d a n i m a l s d i d n o t d i s h a b i t u a t e t o any o f t h e changes f r o m one l i g h t d i s p l a y t o a n o t h e r . S i n c e t h e s e a n i m a l s d i d n o t r e s p o n d t o t h e l i g h t d i s p l a y s on more t h a n t h e f i r s t t r i a l t h e y d i f f e r e d s t a t i s t i c a l l y f r o m SH a n i m a l s . The number o f l i c k s d u r i n g t h e b a s e l i n e p e r i o d d i d n o t , however, d i f f e r between t h e SC and SH a n i m a l s ( D u n n e t t ' s t,oC= 55 A. F i g u r e 12(a-e). The mean number o f l i c k s p e r 5 sec d u r i n g t h e b a s e l i n e ( B ) and d u r i n g t h e p r e s e n t a t i o n o f " s t i m u l u s ( S ) , f o r t h e l i g h t d i s p l a y s w i t h t h e r e d p l a s t i c f i l t e r s removed: ( a ) SH, ( b ) ST, ( c ) SG, (d). SP and ( e ) D P l e s i o n e d a n i m a l s . The a s t e r i s k i n d i c a t e s t h e t r i a l s on w h i c h t h e d i s r u p t i o n o f l i c k i n g was- s t a t i s t i c a l l y r e l i a b l e v - •• c / < ' • -.r • M e a n Number of Licks per 5 S*»c. GROUP DP N * 4 • 6 o c GROUP SP N • 9 o o o . GROUP SC N • 8 •6 o S GROUP ST N= 10 0 o 8 GROUP SH N • 9 6 ,o 6 • 6 ———> i i i > —i—i—i—i—i—i—r~ 1 1 1 1 1 1 1 1 1 1 1 1 1 1 - • • :|: l i i l i i i i < o • < z 0 6 " ' CO - "4*. I'. * y 7. :• • \ : • .1 :' /• • " • /' /' - -/ > „ o z > o n «• CO so » — — — r r - r i i : r . / • l / •i i : • • I : ' I : / : / :• / i I.I i I I i :• • i :• . ' / : ' I : ' - ' / : ' • / . 1 1 1 1 1 1 . 1 V " ' i i i i i i i : / • : /• z a p CO -to .. : / l I / \ : I : / : . ; : . _ \ I I : . 1 : •• / : • ' / / : - /, - y, : A : . l : I. i i i i i i i : A : ' • / : • l 6 z > p g> CO V : \ : • \. : • • /. :• ' ' • 1 : •/•' : / : . / . : l : . / : • " / : • / : .. I : • i A"* : / • 7 : ' / : • / •a 5 6. .05/2, 5, 35 = 7-30). A n a t o m i c a l r e s u l t s . The e x t e n t o f t h e damage t o SG i s p r e s e n t e d i n f i v e r e p r e s e n t a t i v e s e c t i o n s i n F i g u r e 13(a). The h i s t o l o g i c a l r e s u l t s t - w e r e q u i t e , s i m i l a r t o t h o s e ' o f E x p e r i m e n t I . A l l t h e a n i m a l s s u s t a i n e d damage t o t h e s u p e r f i c i a l and deep l a m i n a e o f SG and t h e d o r s a l tegmentum. B e h a v i o r a l - a n a t o m i c a l r e l a t i o n s h i p s . The l e s i o n s f o r i n d i v i d u a l a n i m a l s v a r i e d somewhat i n t h e i r a n t e r i o r o r p o s t e r i o r p l a c e m e n t and t h e i n c l u s i o n o f t h e w h i t e m a t t e r of• t h e p o s t e r i o r c o r -t e x , c e n t r a l g r e y , p r e t e c t a l n u c l e i , hippocampus, and p o s t e r i o r t h a l a -mus . As was t h e c a s e i n E x p e r i m e n t I , t h e m e d i a l p o r t i o n o f SC and d o r s a l tegmentum were a l w a y s i n c l u d e d i n each a n i m a l ' s l e s i o n a nd th e b e h a v i o r a l r e s u l t s d i d n o t v a r y as a f u n c t i o n o f a n t e r i o r - p o s t e r -i o r p l a c e m e n t o r as a f u n t i o n o f t h e i n c l u s i o n o f e x t r a c o l l i c u l a r t i s s u e . S u p e r f i c i a l L a m i n a r L e s i o n s o f S u p e r i o r C o l l i c u l u s ( S P ) . B e h a v i o r a l r e s u l t s . R a t s w i t h l e s i o n s r e s t r i c t e d p r i m a r i l y t o t h e s u p e r f i c i a l l a m i n a o f t h e s u p e r i o r c o l l i c u l u s r e l i a b l y d i s r u p -t e d l i c k i n g on t h e f i r s t 3 t r i a l s i n r e s p o n s e t o l i g h t d i s p l a y S I ( t , cL = .05/2 = 6.16, d f = 30). The' SP a n i m a l s h a b i t u a t e d more r a p i d l y t h a n t h e SH a n i m a l s and d i d n o t d i s h a b i t u a t e t o any o f t h e changes f r o m one l i g h t d i s p l a y t o a n o t h e r . S i n c e t h e SP l e s i o n e d a n i m a l s h a b i t u a t e d more r a p i d l y t h e y were r e l i a b l y d i f f e r e n t f r o m SH a n i m a l s i n r e s p o n s e t o t h e p r e s e n t a t i o n o f t h e l i g h t d i s p l a y s , ( D u n n e t t ' s t , = .05/2; 5, 35» = 7-30), b u t n o t on t h e b a s e l i n e 57 A. F i g u r e 13(A-D). R e p r e s e n t a t i v e s e c t i o n s d e p i c t i n g t h e e x t e n t o f damage t o SC and s u r r o u n d i n g t i s s u e f o r (A) SC, (B) SP, (C) DP and ( D ) a s u r f a c e v i e w o f c o r t i c a l damage and c o r r e s p o n d i n g t h a l a -mic d e g e n e r a t i o n f o r ST a n i m a l s . The s m a l l e s t l e s i o n a t each l e v e l i s r e p r e s e n t e d "by the b l a c k a r e a and t h e l a r g e s t by t h e s t i p p l e d a r e a . 57 B. 5 8. measure. Anatomical results. The extent of the SP lesions are presented at 5-representative levels i n Figure 13(c).. The"lesions were comparable to those described i n Experiment Ij however, i n a few cases they were not as large and were more discretely placed for individual animals. Behavioral-anatomical relationships. The behavioral results and anatomical results were quite variable for this group of animals and, consequently, provided an opportunity to examine the importance of damage to extracollicular structures and areas ofthe SC c r i t i c a l to the SP lesion impairment of behavior. Individual histologies and behavioral results for 2-SP lesioned animals are included i n Figure l4(a-e). Comparing Figure - 14(a) and 14(b)'reveals"that lesions of the superficial laminae of SC must include a large portion of the branchium of the SC to produce the SP typical behavior (i.e., •rapid habituation and.the absence, of dishabituation to changes i n the light display). These'findings were ; replicated, i n 2 addi-tional animals;.-...:- -. - - • Deep Laminar lesions of the Superior Colliculus (DP). Behavioral results• Rats with lesions restricted to the deep laminae of SC reliably disrupted licking i n response, to li g h t display SI on the f i r s t 3 t r i a l s (t, «C = .05/2, = 6.16, df = 30). The results for these animals are presented i n Figure 12(e). The DP lesioned animals habituated quite rapidly to the repeated 59 A. Figure l4(a-b). Histological reconstructions and behavioral results for individual SP lesioned animals for the light displays with the red plastic f i l t e r s removed, (a) SP #14, (b) SP #13. 59 B -p r e s e n t a t i o n o f t h e l i g h t d i s p l a y , u n l i k e t h e SH a n i m a l s , and d i d n o t d i s h a b i t u a t e t o any o f t h e changes f r o m one d i s p l a y t o a n o t h e r . These a n i m a l s d i d n o t d i f f e r s t a t i s t i c a l l y f r o m SH a n i m a l s on t h e b a s e l i n e measure ( D u n n e t t ' s t , = .05/2; 5, 35, = 7-30). A n a t o m i c a l r e s u l t s . The e x t e n t o f damage t o t h e deep l a m i n a e of SC i s d e p i c t e d i n F i g u r e 13(D) i n r e p r e s e n t a t i v e s e c t i o n s . The l e s i o n s were v e r y s i m i l a r t o DP l e s i o n s r e p o r t e d i n E x p e r i m e n t I and d i d n o t v a r y s u s t a n t i a l l y w i t h r e s p e c t t o s i z e and l o c a t i o n . A l l t h e a n i m a l s i n t h i s group had l e s i o n s w h i c h i n c l u d e d t h e l a t e r a l b o r d e r s o f t h e deep l a m i n a e o f SC and t h e d o r s a l tegmentum b u t m i n i m a l i n v o l v e m e n t o f c e n t r a l g r e y and s u p e r f i c i a l l a m i n a e . B e h a v i o r a l - a n a t o m i c a l r e l a t i o n s h i p s . The b e h a v i o r a l and . a n a t o m i c a l r e s u l t s were q u i t e c o n s i s t e n t f o r t h i s l e s i o n g roup. A l l a n i m a l s s u s t a i n e d l e s i o n s as d e s c r i b e d . a n d . t h e - i n d i v i d u a l b e h a v i o r a l r e s u l t s were as- d e s c r i b e d i n .the group a v e r a g e s - o f ' F i g u r e 12(e). S t r i a t e C o r t e x l e s i o n s ( S T ) . B e h a v i o r a l r e s u l t s . A n i m a l s w i t h s t r i a t e l e s i o n s r e l i a b l y d i s r u p t e d l i c k i n g i n r e s p o n s e t o t h e p r e s e n t a t i o n o f t h e l i g h t d i s -p l a y s , h a b i t u a t e d t o t h e r e p e a t e d p r e s e n t a t i o n o f t h e l i g h t s , and d i s h a b i t u a t e d w i t h t h e change i n p a t t e r n o f t h e l i g h t s . "The t r i a l s on w h i c h s t a t i s t i c a l l y r e l i a b l e d i s r u p t i o n o f l i c k i n g o c c u r r e d a r e marked by an a s t e r i s k i n F i g u r e 1 2(b), ( t , X = .05/2 = 6.16, d f = 30). The ST a n i m a l s a p p e a r e d t o h a b i t u a t e more q u i c k l y t o S I and S2 t h a n SH a n i m a l s ; however, t h e y were n o t s i g n i f i c a n t l y 6 1. d i f f e r e n t f r o m SH a n i m a l s when compared "by Dun n e t t ' s t e c h n i q u e ( D u n n e t t ' s t , o< = .05/2; 5, 35 = 7>30), and t h e r e were no s t a t i s t i -c a l l y r e l i a b l e d i f f e r e n c e s between t h e SH and ST a n i m a l s on t h e b a s e l i n e measure. A n a t o m i c a l r e s u l t s . The e x t e n t o f t h e damage t o c o r t e x and c o r r e s p o n d i n g t h a l a m i c d e g e n e r a t i o n i s d e p i c t e d i n F i g u r e 13(e). The s m a l l e s t l e s i o n and one o f t h e l a r g e s t l e s i o n s a r e p r e s e n t e d . B e h a v i o r a l - a n a t o m i c a l r e l a t i o n s h i p s . A n i m a l s w i t h c o m p l e t e d e g e n e r a t i o n o f LGN were n o t d i f f e r e n t i a t e d b e h a v i o r a l l y f r o m sham l e s i o n e d a n i m a l s . As was t h e case f o r one a n i m a l (ST #7) i n E x p e r i -ment I, some o f t h e a n i m a l s i n t h i s group behaved l i k e t h e SG, SP and DP l e s i o n e d a n i m a l s . (They h a b i t u a t e d q u i c k l y and d i d n o t d i s h a -b i t u a t e t o t h e changes i n t h e l i g h t d i s p l a y ) . I n t h e s e c a s e s t h e l e s i o n s were n o t r e s t r i c t e d t o a r e a 17 o n l y , b u t i n c l u d e d e x t r a s t r i a t e c o r t e x and a r e a 7 o f t h e c o r t e x . 6 2. D i s c u s s i o n A l l t h e l e s i o n e d a n i m a l s i n t h i s s t u d y o r i e n t e d t o t h e p r e s e n t a t i o n o f t h e l i g h t s on a t l e a s t t h e f i r s t t r i a l . The SC l e s i o n e d a n i m a l s d i d n o t r e l i a b l y o r i e n t t o t h i s same d i s p l a y when th e l i g h t s , were ' l e s s bright••(i.-e..,>"Experiment'l) . - The a n i m a l s ' " w i t h SC, SP and DP l e s i o n s d i d behave d i f f e r e n t l y f r o m SH a n i m a l s ( t h e y h a b i t u a t e d more q u i c k l y t h a n SH a n i m a l s and d i d n o t d i s h a b i t u -a t e t o any o f t h e changes i n t h e p a t t e r n o f the l i g h t s p r e s e n t e d ) . The SC l e s i o n s d i d n o t , however, r e s u l t i n the e l i m i n a t i o n o f d i s r u p t i o n o f l i c k i n g i n r e s p o n s e t o t h e a p p a r e n t l y moving l i g h t d i s p l a y , - a n d hence, t h e SC c a n n o t be. c o n s i d e r e d e x c l u s i v e l y r e s p o n s i b l e f o r t h e m e d i a t i o n o f t h e o r i e n t i n g r e s p o n s e . F u r t h e r e x a m i n a t i o n s o f t h e i n f l u e n c e o f i n t e n s i t y on o r i e n t i n g were c o n d u c t e d . The o r d e r o f t h e l i g h t d i s p l a y p r e s e n t a t i o n was r e v e r s e d i n a s t u d y d e s c r i b e d i n Ap p e n d i x B and t h e e f f e c t o f t r i p l i n g t h e i n t e n s i t y o f t h e l i g h t s and e l i m i n a t i n g t h e m o t i o n ( p a t t e r n ) was examined and i s i n c l u d e d i n Ap p e n d i x C. The r e s u l t s o f t h e s e s t u d i e s s u g g e s t e d t h a t l a r g e i n c r e a s e s i n t h e i n t e n s i t y o f t h e l i g h t d i s p l a y i n c r e a s e d t h e l i k e l i h o o d o f o b s e r v i n g the o r i e n t i n g r e s p o n s e i n SC l e s i o n e d a n i m a l s and f a c i l i t a t e d o r i e n t i n g indepen^. d e n t l y o f t h e p a t t e r n c h a r a c t e r i s t i c s o f t h e d i s p l a y f o r SC l e s i o n e d a n i m a l s . The p a t t e r n c h a r a c t e r i s t i c s , however, may n o t al w a y s be s e c o n d a r y t o the i n t e n s i t y o f t h e d i s p l a y . The r e l a t i o n s h i p between t h e p a t t e r n o f t h e l i g h t d i s p l a y and t h e i n t e n s i t y o f t h e l i g h t s a r e examined f u r t h e r i n t h e f o l l o w i n g s t u d y . 6 4 . EXPERIMENT I V O r i e n t i n g t o " A p p a r e n t l y " A p p r o a c h i n g and C i r c l i n g L i g h t s The i m p a i r m e n t d e m o n s t r a t e d by SC l e s i o n e d a n i m a l s i n t h e p r e v i o u s s t u d i e s c a n perhaps be d e s c r i b e d as n e g l e c t o r i n a t t e n t i o n t o v i s u a l s t i m u l i w h i c h c a p t u r e n o r m a l a n i m a l s ' a t t e n t i o n and provoke a s i g n i f i c a n t r e a c t i o n . The e x t e n t o f t h e i m p a i r m e n t a p p e a r e d t o be r e l a t e d t o t h e p h y s i c a l i n t e n s i t y and t h e s p e c i f i c p a t t e r n o f t h e l i g h t s employed. I n a d d i t i o n t o i n t e n s i t y and m o t i o n , t h e p a t t e r n c h a r a c t e r -i s t i c s o f a v i s u a l s t i m u l u s may a l s o be an i m p o r t a n t d e t e r m i n a n t o f the o c c u r r e n c e and magnitude o f t h e o r i e n t i n g r e s p o n s e . I n t h e f o l l o w i n g s t u d i e s two a t t e m p t s (A & B) were made t o e v a l u a t e t h e c o n -t r i b u t i o n o f t h e p a t t e r n o f t h e l i g h t d i s p l a y . The l i g h t s o f t h e d i s p l a y s a p p e a r e d t o " a p p r o a c h " o r " r e c e d e " i n I V ( A ) and t o c i r c l e t h e e n t i r e d i s p l a y i n I V ( B ) . The a c t u a l " change i n the. l i g h t i n t e n s i t y and amount o f a p p a r e n t m o t i o n o f t h e l i g h t d i s p l a y were, however, r e d u c e d r e l a t i v e t o t h o s e o f the p r e c e d i n g s t u d i e s . Method S u b j e c t s I n E x p e r i m e n t I V ( A ) , t h e s u b j e c t s were n a i v e Long-Evans hooded r a t s : 6 s u s t a i n e d l a r g e b i l a t e r a l SG, 4 SP, 4 DP, 4 ST, and 6 SH l e s i o n s . I n E x p e r i m e n t I V ( B ) , Zk n a i v e r a t s were t e s t e d : , 8 s u s t a i n e d l a r g e b i l a t e r a l SG, 4 SP, h DP, k ST, and 8 SH l e s i o n s . S u r g e r y and a n i m a l maintenance were i d e n t i c a l t o t h a t d e s c r i b e d i n E x p e r i m e n t I . A p p a r a t u s The a p p a r a t u s was i d e n t i c a l t o t h a t d e s c r i b e d i n E x p e r i -ment I . P r o c e d u r e The p r o c e d u r e was i d e n t i c a l t o E x p e r i m e n t I . The l i g h t d i s p l a y s f o r each s t u d y were: (A) (51) "Apparently"- a p p r o a c h i n g l i g h t d i s p l a y . The m i d d l e l i g h t i n t h e m i d d l e p a n e l was i l l u m i n a t e d f o r l / l O sec f o l l o w e d by th e r i g h t and l e f t l i g h t s i n t h e m i d d l e p a n e l f o r l / l O s e c ? t h e n t h e l e f t l i g h t o f t h e r i g h t p a n e l and t h e r i g h t l i g h t o f t h e l e f t p a n e l , e t c . The l i g h t s a p p e a r e d t o move f r o m t h e m i d d l e o f t h e box t o t h e extremes o f t h e p a n e l s o r t o a p p r o a c h t h e a n i m a l i n a n a s a l t o t e m p o r a l d i r e c t i o n . The i n t e r l i g h t i n t e r v a l was " i / i O s e c . (52) ; " A p p a r e n t l y " r e c e d i n g l i g h t d i s p l a y . . T h i s d i s p l a y was i d e n t i c a l t o S I ; however, t h e d i r e c t i o n o f t h e l i g h t s was changed s u c h t h a t t h e l i g h t s a p p e a r e d t o r e c e d e f r o m t h e extremes o f t h e panels to the middle light. That i s , the lights appeared to move in a temporal to nasal direction by presenting f i r s t the l e f t light of the l e f t panel and the right light of the right panel, then the next two adjacent lights.,, etc. - (S3)-ffApparently"••approaching-'light .display. The display was identical to SI; however, the lights were illuminated for l/5 sec. -(S4),"Apparently" receding lig h t display. The display was identical to S2, however, the lights were illuminated for l/5 sec and the interlight interval was l/5 sec. The lights were covered by the red plastic f i l t e r s for the above stimulus displays, and light intensities were:!: for 1 light on 2 • 2 ."6l cd/m , • and for'2 lights on .65 cd/m SI was presented on t r i a l s 1-15, S2 on t r i a l s 16-30, S3 on t r i a l s 31-35, and S4 on t r i a l s 36-40. (B) (51) Circling light display. The lights appeared to move across the entire set of nine lights from right to l e f t ( c i r c l i n g ) . The f i r s t light on the right was illuminated for l/lO sec followed by the second, then the third, etc., to the ninth with an interlight interval of l/lO sec. (52) Circling light display. This display was identical to that described above; however, each ligh t was illuminated for l/5 sec and the interlight interval was 1/5 sec. (53) 1 Random light display. The lights appeared to "jump" from one position to another i n this display. A single light was illuminated for l/lO sec and the interlight interval was. '1/10 sec. The l i g h t s were i l l u m i n a t e d i n a random o r d e r . The r e d p l a s t i c f i l t e r s were u s e d i n a l l o f t h e above l i g h t d i s p l a y s . The i n t e n s i t y o f one l i g h t measured a t t h e w a t e r s p o u t was .61 cd/m . S I was p r e s e n t e d on t r i a l s 1-10, S2 on t r i a l s 11-20,and S3 on t r i a l s 21-30. 6 8 ' R e s u l t s (A) Approaching-Receding- L i g h t ' D i s p l a y s . The r e s u l t s o f p r e s e n t i n g l i g h t s w h i c h a p p e a r e d t o "ap p r o a c h " o r " r e c e d e " a r e p r e s e n t e d i n F i g u r e 15(a-e). The r e s u l t s o f t h e a n a l y s i s o f v a r i a n c e c o m p a r i n g t h e SH, ST, SG, SP, and DP l e s i o n e d groups a r e p r e s e n t e d i n T a b l e 6 o f Appendix A. T r i a l s on w h i c h d i s r u p t i o n o f l i c k i n g i n r e s p o n s e t o p r e s e n t a t i o n o f t h e l i g h t s was r e l i a b l y d i f f e r e n t f r o m l i c k i n g d u r i n g b a s e l i n e a r e marked by an a s t e r i s k i n F i g u r e 15 ( t , *.= .05/2 = 7.87, d f = 19). As c a n be s e e n i n t h e f i r s t p a n e l o f F i g u r e 15(a-e), p r e s e n t a t i o n o f l i g h t s w h i c h a p p e a r e d t o approach t h e a n i m a l c a u s e d a marked d i s r u p t i o n i n l i c k i n g on a t l e a s t t h e f i r s t 3" t r i a l s f o r a l l t h e a n i m a l s t e s t e d . A l l t h e a n i m a l s d i s r u p t e d l i c k i n g and a p p e a r e d t o l o o k a t t h e l i g h t s when t h e a p p r o a c h i n g l i g h t s ( S i ) were p r e s e n t e d . A-few o f t h e SH a n i m a l s ..reared, approached. t h e p l e x i g l a s s p a n e l and a p p e a r e d t o f o l l o w t h e m o t i o n o f t h e l i g h t s ; however, t h e m a j o r i t y o f t h e SH a n i m a l s and a l l t h e SC l e s i o n e d a n i m a l s t u r n e d away f r o m t h e w a t e r s p o u t and l i g h t d i s p l a y . W h i l e a l l t h e SC l e s i o n e d a n i m a l s o r i e n t e d t o t h e l i g h t d i s p l a y ( S i ) , t h e y r e q u i r e d f e w e r t r i a l s t o h a b i t u a t e t o t h i s l i g h t d i s p l a y . S i n c e t h e y h a b i t u a t e d more q u i c k l y , t h e y were r e l i a b l y , d i f f e r e n t f r o m SH a n i m a l s ( F = 1.50, d f = 36, 171, P_ = .05; D u n n e t t ' s t , OL= .05/2, 5, 19, = 9.18). -When-the. e n t i r e 1 5 - t r i a l s i n r e s p o n s e t o S I and S2 were i n c l u d e d i n t h e a n a l y s i s ( T a b l e 7, Appendix A), the SH animals disrupted licking when SI was presented on t r i a l s 1-8 while the ST,-.lesioned--,animals-disrupted licking .on only the f i r s t 5-, the SC on 4-, the SP on 3, and the...DP on- 5 t r i a l s . In addition to the differences between the SC lesioned animals and SH animals i n the rate of.habituation, dishabituation to the changes i n the light display was not as consistent or pronounced for SC lesioned animals. The DP lesioned animals did not dishabitu-ate to any of the changes i n the pattern of the lights. The SC, SP, and ST animals clearly dishabituated to some of the changes i n the pattern of the lights (marked by an asterisk i n Figure 15). The histological results f o r the lesioned animals are presented i n Figure l"6(a-d). The lesions for a l l the groups are quite similar to those presented i n the previous experiments. With the exception of the ST lesioned animals, there was l i t t l e variation i n the anatomical and behavioral results and individual animals are represented by the group averages. The ST lesions were more extensive for the animals i n this study than 'in previous studies. Two animals had asymmetrical lesions which were restricted primarily to area 17 on one side and included areas 17, 18, 18A,and 7 on the other. These animals' behavior was identical to the SH animals. They disrupted licking on at least the f i r s t 5 t r i a l s and dishabituated to a l l the changes in the Tights. Two additional animals had extensive cortical lesions which included area 17, 18, l8A,and area 7 b i l a t e r a l l y . These animals' behavior was more like that of the SC animals in that they only disrupted licking 70 A. F i g u r e 15(a-e). Mean number o f l i c k s p e r 5 s e c d u r i n g b a s e l i n e (B) and d u r i n g t h e p r e s e n t a t i o n o f t h e s t i m u l u s ( s ) , f o r t h e " a p p r o a c h -i n g " l i g h t d i s p l a y s : S I , S2, S3 and S4. ( a ) SH, (b) ST, ( c ) SG, (d) SP and ( e ) DP l e s i o n e d a n i m a l s . The a s t e r i s k i n d i c a t e s t h e t r i a l s on w h i c h d i s r u p t i o n o f l i c k i n g was s t a t i s t i c a l l y r e l i a b l e . ro a o cr OJ w w w w w Mean Number of Licks per 5 Sec. GROUP DP IN * 4) GROUP SP [N ' 4) GROUP SC [N = 6) GROUP ST [N-4 1 GROUP SH (N • 6) * : / • / i i i i i i i • * ^ - — # — * i i i ; i _ — - — - ~ # 1 1 1 ! 1 1 1 1 ~ * -""* ^ * : / :• / : / : \ : ' \ : \ : " / : I: : y : \ i i i i i 1 1 : ' / : . / :. / : y : X : I : \ : • \ i i i i i i i : • I : y : I : l i i i i i i i i : / : i : / :. / :'• / .. : l :. • • 1 • I 1 1 1 1 1 1 : ; y : ./ : J : / : y : / •a oL : / : / : • \ y y* : . /. : ' / '• : I i i i i i i i >  — • 71 A . F i g u r e 16 ( A-D). R e p r e s e n t a t i v e s e c t i o n s d e p i c t i n g t h e e x t e n t o f damage t o SG and s u r r o u n d i n g t i s s u e f o r (A) SC, (B) SP, (c) DP and (D) ST l e s i o n e d a n i m a l s . The s m a l l e s t l e s i o n a t each r e p r e s e n t a t i v e s e c t i o n i s drawn i n b l a c k and t h e l a r g e s t i s s t i p p l e d . 71 B . on the f i r s t 2-3 t r i a l s and dishabituated to no more than one of the changes from one light display to another. (B)'.'.Circling Light Displays.' The results of presenting lights which appeared to circ l e or move across the set of nine lights are diagrammed i n Figure 17 (a-e). The results of the analysis of variance comparing the SH, SC, SP, DP, and ST lesioned groups are presented i n Table 8 of Appen-dix A. Trials on which disruption of licking i n the presence of the lights was reliably different from licking during baseline are marked by an asterisk i n Figure 17(a-e), (t, oC = .05/2, = 6.82; df = 20). A l l of the animals reliably disrupted li c k i n g on .at least the f i r s t 3 t r i a l s when light display SI was presented. A l l the ani-mals disrupted licking and appeared to look at the lights. The SH animals followed the motion of the lights. The SC lesioned animals appeared to look at the lights b r i e f l y then turned away from the water spout and lights. Dishabituation was hot demonstrated to the change i n speed of the lights from l/lO sec to l/5 sec for any of the groups. The SH animals, however, reliably disrupted licking when the random light display (S3) was presented. None of the SC, SP, DP, or ST animals dishabituated to this li g h t display. The histological results for each of the lesion groups are summarized i n Figure 18 . The extent of damage for each group i s quite similar to that of the previous studies. There was l i t t l e variation i n lesion size and placement within the groups and the individual animals are represented by the average data. 73 A . F i g u r e l ? ( a - e ) . Mean number o f l i c k s p e r 5 sec d u r i n g t h e b a s e -l i n e (B) and d u r i n g the p r e s e n t a t i o n o f t h e s t i m u l u s ( S ) , f o r t h e c i r c l i n g l i g h t d i s p l a y s : S I , S2, and S3. The a s t e r i s k i n d i c a t e s t h e t r i a l s on w h i c h d i s r u p t i o n o f l i c k i n g was s t a t i s t i c a l l y r e l i a b l e . Mean Number of Licks per 5 Sec. GROUP DP N • 4 o o 8 GROUP SP N • 4 5 a o GROUP SC N • 8 GROUP 5T N -- 4 GROUP SH N • 8 cn o ( A s s \ I I \ ; I / ; \ \ \ ' \ \ \ \ I I \ I •I I I I . I i \ N ; \ r I * \ i i i i * i i I / ; \ 74 A . F i g u r e 1 8 ( A - D ) . R e p r e s e n t a t i v e s e c t i o n s d e p i c t i n g t h e e x t e n t o f damage t o SG and s u r r o u n d i n g t i s s u e f o r ( A ) SG, (B) SP, (C) DP and (D) a s u r f a c e v i e w o f c o r t i c a l damage and c o r r e s p o n d i n g t h a l a m i c d e g e n e r a t i o n f o r ST a n i m a l s . The s m a l l e s t l e s i o n a t each l e v e l i s r e p r e s e n t e d by t h e b l a c k a r e a and t h e l a r g e s t by the s t i p p l e d - a r e a . \ 74 B. D i s c u s s i o n These s t u d i e s c l e a r l y d e m o n s t r a t e d t h a t SC l e s i o n e d a n i m a l s a r e c a p a b l e o f d i s r u p t i n g t h e i r o n g o i n g b e h a v i o r and l o c a l i z i n g a v i s u a l s t i m u l u s . Of p a r t i c u l a r i n t e r e s t i n t h e s e s t u d i e s was t h e f i n d i n g t h a t t h e SC l e s i o n e d a n i m a l s o r i e n t e d t o t h e l i g h t d i s p l a y s w h i c h a c t u a l l y i n v o l v e d mueh: dimmer l i g h t s , than- t h o s e v u s e d i n . ' p r e v i o u s s t u d i e s . . The l i g h t d i s p l a y s a p p e a r e d -to. have a greater.•impact- i n •terms-of. t h e p a t t e r n o f movement o f t h e l i g h t s . >;""" " ""The S H i a n i m a l s were more r e s p o n s i v e t o t h e a p p r o a c h i n g and r e c e d i n g d i s p l a y s i n t h a t t h e y r e q u i r e d , more, t r i a l s t o r h a b i t u a t e " t o » • them t h a n t h e " ' l i g h t d i s p l a y s -of 'the p r e v i o u s s t u d i e s . I n terms o f t h e r a t e of h a b i t u a t i o n t o t h e d i s p l a y , t h e SH a n i m a l s were n o t s i g n i f y i c a n t l y more r e s p o n s i v e t o t h e c i r c l i n g l i g h t s d i s p l a y t h a n t o t h e d i s p l a y s u s e d i n t h e p r e v i o u s s t u d i e s . The SH a n i m a l s d i d , however, a t t e m p t t o f o l l o w t h e c i r c l i n g l i g h t s and i n t h i s way a p p e a r e d t o be more r e s p o n s i v e t o t h i s d i s p l a y . The magnitude o f o r i e n t i n g , t h e r a t e o f h a b i t u a t i o n , duraA t i o n o f l o o k i n g a t t h e l i g h t s , and e l i c i t a t i o n o f f u r t h e r e x p l o r a t o r y a c t i v i t y d i r e c t e d towards t h e l i g h t d i s p l a y a r e l i k e l y a l l p o s s i b l e measures o f t h e s a l i e n c e o f a p a r t i c u l a r v i s u a l s t i m u l u s . The r e l a -t i o n s h i p between t h e s e measures has n o t been examined s y s t e m a t i c a l l y i n t h i s s t u d y . W h i l e t h e s e r e l a t i o n s h i p s warrant' f u r t h e r s t u d y , t h e f o c u s o f t h e p r e s e n t r e p o r t was t o d e t e r m i n e i f SC l e s i o n e d a n i m a l s were c a p a b l e o f o r i e n t i n g t o v i s u a l s t i m u l i and t h e y c l e a r l y d i d o r i e n t t o t h e s t i m u l i u s e d i n t h i s s t u d y . The p a t t e r n o f m o t i o n i n t h e l i g h t d i s p l a y a p p e ars t o he an i m p o r t a n t p a r a m e t e r i n demon-s t r a t i n g t h i s r e s p o n s e . The p a t t e r n o f t h e l i g h t d i s p l a y may i n f l u -ence t h e magnitude o f t h e o r i e n t i n g r e s p o n s e as a f u n c t i o n o f i t s s a l i e n c e and i n terms o f i t s p o s s i b l e b e h a v i o r a l s i g n i f i c a n c e . These s u g g e s t i o n s a r e i n d i r e c t l y examined i n t h e f o l l o w i n g s t u d i e s . 77. EXPERIMENT V The E f f e c t o f M a n i p u l a t i o n o f an I n t r i n s i c P a r a m e t e r on O r i e n t i n g I n t h e I n t r o d u c t i o n , i t was a r g u e d t h a t t h e o r i e n t i n g r e s p o n s e was n o t a s i m p l e r e f l e x i v e b e h a v i o r t h a t i n e v i t a b l y o c c u r s t o t h e p r e s e n c e o f a v i s u a l s t i m u l u s . The o r i e n t i n g r e s p o n s e was s a i d t o be c o n t r o l l e d by a number o f p a r a m e t e r s . These m i g h t be c a t e g o r i z e d as e i t h e r e x t r i n s i c t o t h e a n i m a l and s p e c i f i c a l l y r e l a -t e d t o t h e s t i m u l u s c h a r a c t e r i s t i c s ( e . g . , t h e p a t t e r n , i n t e n s i t y o r s i z e o f t h e s t i m u l u s ) o r as i n t r i n s i c t o t h e a n i m a l . The l a t t e r c a t -e g o r y c o u l d i n c l u d e v a r i a t i o n i n t h e a n i m a l i s a l e r t n e s s o r a r o u s a l , o r s t a t e o f d e p r i v a t i o n , as w e l l as p r i o r e x p e r i e n c e w i t h t h e s t i m u l i ( e . g . , t h e i r n o v e l t y o r p r e v i o u s a s s o c i a t i o n w i t h a v e r s i v e o r r e w a r d -i n g c o n s e q u e n c e s ) . The f o l l o w i n g s t u d y examined one o f t h e s e f a c t o r s ; s t a t e o f d e p r i v a t i o n . T h i s was a c c o m p l i s h e d by a l l o w i n g t h e a n i m a l s a c c e s s t o a d d i t i o n a l w a t e r p r i o r t o t e s t i n g . 7 8 Method S u b j e c t s A t o t a l o f 16 n a i v e r a t s were t e s t e d : 4 l a r g e b i l a t e r a l SG, 4 SP, k DP, and 4 SH l e s i o n e d a n i m a l s were t e s t e d . H a l f t h e s u b j e c t s i n e a ch group were o b t a i n e d f r o m t h e b r e e d e r s and h a l f were r e a r e d i n t h e B i o p s y c h o l o g y V i v a r i u m a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a . I n a l l o t h e r r e s p e c t s t h e s u b j e c t s were t r e a t e d as i n t h e p r e v i o u s s t u d i e s . A p p a r a t u s The a p p a r a t u s was i d e n t i c a l t o t h a t d e s c r i b e d i n E x p e r i m e n t I . P r o c e d u r e The p r o c e d u r e was i d e n t i c a l t o t h a t d e s c r i b e d i n E x p e r i m e n t I w i t h t h e f o l l o w i n g e x c e p t i o n s : - ( l ) The a n i m a l s were a l l o w e d a c c e s s t o w a t e r i n t h e i r home cages f o r 30 m i n u t e s , two t o t h r e e h o u r s p r i o r t o t e s t i n g . (-2) The dimmer l i g h t s ( w i t h r e d p l a s t i c f i l t e r s ) were u s e d i n t h i s e x p e r i m e n t . (3) The a p p a r e n t l y moving s t i m u l u s 1 p e r l / l O s e c ( S i ) was p r e s e n t e d on t h e f i r s t 5 t r i a l s and t h e s t a t i o n a r y 1 p e r l / l O se c (S2) was p r e s e n t e d on t h e 6th t o 10th t r i a l s . The a p p a r e n t l y moving 1 p e r l/5 sec (S3) and t h e s t a t i o n a r y 1 p e r l/5sec (S4) s t i m u l i were a l s o p r e s e n t e d f o r 5 t r i a l s e a c h on t h e 11th t o 15th t r i a l s and l6th t o 20th t r i a l s , r e s p e c t i v e l y . R e s u l t s The r e s u l t s o f m a n i p u l a t i n g h o u r s o f w a t e r d e p r i v a t i o n a r e p r e s e n t e d i n F i g u r e 19 and t h e a n a l y s i s o f v a r i a n c e i s i n c l u d e d i n T a b l e 9 o f Appendix A. The d i f f e r e n c e s between l i c k i n g d u r i n g t h e b a s e l i n e and t h e s t i m u l u s p r e s e n t a t i o n on each t r i a l w h i c h were s t a t i s t i c a l l y r e l i a b l e ( t , oL = .05/2, = 9•53» d f = 12) a r e marked by an a s t e r i s k i n F i g u r e 19. A l l t h e a n i m a l s d i s r u p t e d l i c k i n g i n r e s -ponse t o t h e p r e s e n t a t i o n o f S I on a t l e a s t t h e f i r s t t h r e e t r i a l s , h a b i t u a t e d w i t h r e p e a t e d s t i m u l u s p r e s e n t a t i o n s , and d i s h a b i t u a t e d t o the changes o f l i g h t s f r o m one p a t t e r n t o a n o t h e r . The amount o f d i s r u p t i o n on t h e s e t r i a l s d i d n o t r e l i a b l y d i f f e r f o r t h e SH and SG l e s i o n e d a n i m a l s . The^number o f t r i a l s r e q u i r e d t o h a b i t u a t e t o the r e p e a t e d p r e s e n t a t i o n o f t h e l i g h t s was a l s o n o t r e l i a b l y d i f f e r e n t . D i s h a b i t u a t i o n t o t h e change i n th e p a t t e r n o f t h e l i g h t s was n o t as c o n s i s t e n t f o r t h e SG, SP, and DP l e s i o n e d s u b j e c t s as i t was f o r t h e SH a n i m a l s . S t a t i s t i c a l l y r e l i a b l e d i s r u p t i o n o f l i c k i n g i n r e s p o n s e t o t h e change i n t h e l i g h t d i s p l a y o f t e n d i d n o t o c c u r u n t i l t h e s e c o n d t r i a l f o r t h e s e animals.. c.. (The a v e r a g e d d a t a f o r t h e DP l e s i o n e d a n i m a l s a r e some-what m i s l e a d i n g . A c c o r d i n g t o t h e a v e r a g e d d a t a , t h e DP l e s i o n e d a n i m a l s a p p e a r e d t o d i s h a b i t u a t e as c o n s i s t e n t l y as t h e SH a n i m a l s . T h i s group t r e n d was p r o d u c e d by t h e pe r f o r m a n c e o f one a n i m a l . T h i s a n i m a l ' s l e s i o n o n l y damaged t h e l a t e r a l edge, o f t h e SG, n o t the m e d i a l h a l f o f t h e deep SC l a m i n a e and a d j a c e n t tegmentum). The SP a n d SC l e s i o n e d a n i m a l s ' h i s t o l o g i c a l r e s u l t s were q u i t e s i m i l a r 80 A. F i g u r e 19(a-d). Mean number o f l i c k s p e r 5 s e c d u r i n g t h e b a s e -l i n e ( B ) and d u r i n g the p r e s e n t a t i o n o f t h e s t i m u l u s ( S ) f o r l i g h t d i s p l a y s S I , S2, S3 and S4. ( a ) S H , ( b ) S C , ( c ) S P and (d) D P l e s i o n e d a n i m a l s . - The a s t e r i s k i n d i c a t e s t h e t r i a l s on w h i c h d i s r u p - ' t i o n o f l i c k i n g was s t a t i s t i c a l l y r r . e 11 able". 8 1. to those reported'in the previous studies. The extent of the damage for each lesion group i s depicted i n Figure .20 at representative levels of the SC. More important than the quantitative differences between lesioned groups-mentioned above-is the;comparison-of the :results of this study within the results of . Experiment 1. The- results of - the analysis of variance which compared the two experiments are presented i n Table 10 of Appendix A. Access to extra water prior to the test session resulted in: ( l ) s t a t i s t i c a l l y reliable disruption of licking i n response to the lights by the SC lesioned animals (t, c{. = .05/2, = 7.45, df = 30), (2) dishabituation to the change i n light patterns by the lesioned animals (t, ^  = .05/2, = 7.45, df = 30), and (3) an increase i n the number of t r i a l s on which a l l the animals reliably disrupted licking i n response to the stimuli (F = 5-91, df = 1, 39, £ = -05). 82 A. Figure 20(A-G). Representative sections depicting the extent of damage to SC and surrounding tissue for (A) SC, (B) SP and (c) DP lesioned animals. The smallest lesion at each representative level i s drawn in black and the largest is stippled. 82 B. 8 3. D i s c u s s i o n The r e s u l t s o f t h i s s t u d y a g a i n d e m o n s t r a t e d t h a t SC l e s i o n e d a n i m a l s a r e , i n f a c t , c a p a b l e o f o r i e n t i n g t o a v i s u a l s t i m u l u s . F u r t h e r , the SC a n i m a l s o r i e n t e d t o t h e l i g h t d i s p l a y t h a t was i g n o r e d when p r e s e n t e d f o l l o w i n g a l o n g e r p e r i o d o f w a t e r d e p r i v a t i o n . The e f f e c t o f v a r y i n g amounts o f w a t e r d e p r i v a t i o n on d i s r u p t i o n t o a v i s u a l s t i m u l u s , h a b i t u a t i o n , a n d d i s h a b i t u a t i o n have n o t been examined p a r a m e t r i c a l l y i n t h i s s t u d y . The s t u d y does, how-e v e r , c l e a r l y p r o v i d e some d a t a i n "support o f - t h e p r o p o s a l - t h a t i n t r i n s i c v a r i a b l e s i n f l u e n c e t h e o r i e n t i n g r e s p o n s e . The SH a n i m a l s d e m o n s t r a t e d enhanced r e s p o n d i n g on t h e f i r s t t r i a l s t o S I and d i s h a b i t u a t i o n t o the change i n s t i m u l i was a l s o p o t e n t i a t e d f o r t h e s e a n i m a l s . More i m p o r t a n t l y , t h e m a n i p u l a t i o n o f amount o f w a t e r consumed p r i o r t o t e s t i n g r e s u l t e d i n : ( l ) r e s p o n d i n g t o t h e s t i m u l i by t h e SC l e s i o n e d animals,'(2) p r o l o n g e d r e s p o n d i n g and s l o w e r h a b i t u a t i o n ( r e l a t i v e t o the number o f t r i a l s r e q u i r e d f o r h a b i t u a t i o n i n t h e p r e v i o u s s t u d i e s ) , and (3) d i s h a b i t u a t i o n t o a t l e a s t some o f t h e changes i n t h e s t i m u l i . O b s e r v a t i o n o f a few o f t h e l e s i o n e d and SH a n i m a l s d u r i n g t h e d i s r u p t i o n o f l i c k i n g on t h e f i r s t t r i a l d i d n o t r e v e a l s y s t e m a -t i c d i f f e r e n c e s between t h e g r o u p s . A l l t h e a n i m a l s o b s e r v e d i n t h i s s t u d y , l i f t e d t h e i r heads f r o m t h e w a t e r s p o u t , a p p e a r e d t o l o o k a t t h e l i g h t s f o r v a r y i n g amounts o f time., and t h e n g e n e r a l l y t u r n e d t o e x p l o r e t h e box o r groom. The SH a n i m a l s a p p e a r e d t o spend more ti m e f a c i n g t h e l i g h t s t h a n t h e SC l e s i o n e d a n i m a l s , w h i c h g e n e r a l l y a p p e a r e d t o l o o k a t t h e l i g h t s f o r a much s h o r t e r t i m e and t h e n engaged i n o t h e r a c t i v i t i e s . 85. EXPERIMENT VI Moving and Stationary Light Displays as Signals of Aversive Reinforcement. The preceding studies demonstrated that SG lesions did not result i n visual agnosia or the i n a b i l i t y to perform the appro-priate motor responses involved i n orienting. Rather, the orienting response was possible but not always emitted i n response to stimuli that normal animals readily oriented to. The behavioral d e f i c i t manifested by the SG lesioned animals can perhaps be appropriately described as visual neglect or inattention, i n that the animals were less easily distracted by visual stimuli. The SG lesioned animals i n the previous studies oriented to the light displays which the intact animals treated as more salient and the orienting d e f i c i t to the less salient light display was reduced by manipulating the amount of water consumed prior to testing. The following study represents an additional attempt to verify that the SC lesioned animals were not blind to the specific light display that they had ignored. 86. Method- Subjects A total of 40 naive rats were tested. Eight sustained b i l a t e r a l SC, 8 SP, 8 DP, 8 ST,and 8 SH lesions. Surgery and main-tenance of the animals was identical to that described i n Experiment I. Apparatus The apparatus was identical to the apparatus described i n Experiment l,:'with one exception. A scrambled shock source (BRS model SGS-0C4) produced a 1 milliampere (mA) electric shock to the grid floor of the testing apparatus. Procedure The procedure involved 2 phases. Phase 1 was identical to Experiment I for 4 animals i n each of the lesion groups: SC, SP, DP, and SH, and the 8 ST animals. The remaining rats were tested i n Experiments I, III, V, and Appendix B, and proceeded to phase 2 of this study. The order of presentation of the light displays i n phase 1 and the light display followed by shock i n phase 2 are described i n Table 1. Phase 2 of the procedure began on the day immediately following the completion of phase 1. At this time the 5 sec presen-tation of the stimulus display was immediately followed by an una-voidable 1 mA shock to the feet through the grid floor of the box for 1 sec. The number of licks during the baseline 5 sec period and the 5 sec stimulus presentation were recorded as i n Experiment I. 87. T a b l e 1 Assignment o f A n i m a l s , E x p e r i m e n t I V Phase 1 - Phase.:i 2 L e s i o n Group E x p e r i m e n t ... O r d e r o f the L i g h t s D i s p l a y {. l i g h t D i s p l a y . F o l l o w e d "by Shock SH , "SC ,• • n- = 2: Exp. VI - 'Ml/lO, S l / l O , .Hi/5-, s i / 5 :/~:Ml/lOO SP ;& DP h = 2 Exp".; VI S l / l ' O , Ml/10, S l / 5 , Ml/5 Sl/10 n =' 2 Exp. V Ml/10. Sl/10, Ml/5, S l / 5 Ml/10 n - 2 A p p e n d i x B S l / 5 , Ml/5, Sl/10, Ml/10 Sl/10 ST n =: '.2 Exp.-VI Ml/10, Sl/10, Ml/5, S l / 5 Ml/10 n = 2 Exp. VI Sl/10, M.i/10, S l / 5 , Ml/5 Sl/10 n = 2 Exp. I l l Ml/10,. S'i/10, Ml/5, S l / 5 Ml/10 ... n = 2 Exp. I Ml/10, Sl/10, Ml/5, s i / 5 Sl/10 Note. M l / l O = a p p a r e n t l y moving l i g h t d i s p l a y , 1 p e r l / l O s e c . S l / l O = s t a t i o n a r y l i g h t d i s p l a y , 1 p e r l / l O s e c . Ml/5 = a p p a r e n t l y moving l i g h t d i s p l a y , 1 p e r l/5 s e c . S l / 5 = s t a t i o n a r y l i g h t d i s p l a y , 1 p e r l/5 s e c . 8.8. However, the number of licks which initi a t e d the presentation of the lig h t display was varied between 8 and approximately 130 l i c k s . This was accomplished by resetting the counting mechanism a variable number of times after each baseline 5 seconds had elapsed. In this way a random number of licks -was interspersed between the baseline and stimulus presentation. This was done to prevent the amount of drinking serving as a cue to the onset of stimulus and shock.• In all-respects, r./this-phasewasidentical .to.phase i except that the presentation of the light display was immediately followed by the onset of the shock. Half the animals were shocked following the presentation of the apparently moving at 1 per l/lO sec and half following the stationary 1 per l/lO sec light display. The stimulus assigment was made on the basis of whether the moving or stationary display was presented f i r s t i n phase 1. Ten t r i a l s were presented • i n each session. Daily sessions of 10 t r i a l s were continued u n t i l the animals suppressed licking i n the presence of the lights to a criterion 6nrl8 t r i a l s for two successive sessions. The suppression criterion was a ratio of .90 determined by (number-ofclicks-during . baseline - number of li c k s during stimulus pre'sentation)/(number of-l i c k s during baseline). :? .9. R e s u l t s Phase 1: The r e s u l t s f o r phase 1 o f t h i s e x p e r i m e n t were i d e n t i c a l t o t h o s e o f E x p e r i m e n t I and s u c c e s s f u l l y r e p l i c a t e d t h o s e f i n d i n g s . The SH and ST l e s i o n e d a n i m a l s d i s r u p t e d l i c k i n g t o S I , h a b i t u a t e d to. i t s r e p e a t e d p r e s e n t a t i o n , and d i s h a b i t u a t e d t o t h e changes i n t h e l i g h t d i s p l a y s . The SG and DP l e s i o n e d a n i m a l s _ d i d n o t d i s r u p t l i c k i n g i n r e s p o n s e t o t h e l i g h t d i s p l a y s on any o f t h e t r i a l s . The SP l e s i o n e d a n i m a l s r e l i a b l y d i s r u p t e d l i c k i n g t o S i l a n d h a b i t u a t e d t o i t s r e p e a t e d p r e s e n t a t i o n b u t d i d n o t d i s h a b i t u a t e t o any o f t h e changes i n t h e l i g h t d i s p l a y s . Phase 2: The r e s u l t s o f t h e a n a l y s i s o f v a r i a n c e c o m p a r i n g t h e l e s i o n e d a n i m a l s on t h e number o f t r i a l s t o c r i t e r i o n a r e p r e s e n t e d i n T a b l e 11 o f Appendix A. A l t h o u g h t h e a n i m a l s s h o c k e d f o l l o w i n g p r e s e n t a t i o n o f t h e s t a t i o n a r y l i g h t d i s p l a y r e q u i r e d more t r i a l s t o r e a c h t h e s u p p r e s s i o n c r i t e r i o n t h a n t h e a n i m a l s s h o c k e d f o l l o w -i n g p r e s e n t a t i o n o f t h e moving l i g h t d i s p l a y , t h e d i f f e r e n c e was n o t s t a t i s t i c a l l y r e l i a b l e ( F = 2.97; d f = 1, 30;_p = .095)- The mean number o f t r i a l s r e q u i r e d t o r e a c h t h e s u p p r e s s i o n c r i t e r i o n f o r e a c h o f t h e l e s i o n groups o f a n i m a l s a r e p r e s e n t e d i n F i g u r e 21. As c a n be see n i n t h e f i g u r e , t h e SG and DP l e s i o n e d a n i m a l s r e q u i r e d f e w e r t r i a l s t o r e a c h t h e s u p p r e s s i o n c r i t e r i o n t h a n SH and SP a n i m a l s and t h e ST l e s i o n e d a n i m a l s r e q u i r e d s u b s t a n t i a l l y more t r i a l s t h a n t h e SH a n i m a l s t o r e a c h c r i t e r i o n ( F = 6.15; d f = 4, 30; 90 A. F i g u r e 21. Mean number o f t r i a l s t o c r i t e r i o n s u p p r e s s i o n and v a r i a n c e f o r SH, SC, SP, DP and ST l e s i o n e d a n i m a l s . 9 1. £ = .001; D u n n e t t ' s t , <* = .05/2, 5, 30 = 17-56) • An a d d i t i o n a l a n a l y s i s o f v a r i a n c e was c o n d u c t e d t o examine d i f f e r e n c e s between- t h e l e s i o n e d a n i m a l s d u r i n g a c q u i s i t i o n o f t h e c o n d i t i o n e d s u p p r e s s i o n r e s p o n s e . I n t h i s a n a l y s i s t h e d i f -f e r e n c e s between l i c k i n g d u r i n g b a s e l i n e and t h e p r e s e n t a t i o n o f the l i g h t s were a s s e s s e d f o r t h e f i r s t 4 s e s s i o n s . (The u n e q u a l number of t r i a l s r e q u i r e d t o r e a c h t h e s u p p r e s s i o n c r i t e r i o n p r e -c l u d e d a n a l y s i s o f a l l t h e s e s s i o n s ) . The r e s u l t s o f t h e a n a l y s i s o f v a r i a n c e a r e p r e s e n t e d i n T a b l e 12 o f App e n d i x A. None o f t h e i n t e r a c t i o n s o r the main e f f e c t c o n t r a s t i n g t h e s p e c i f i c l i g h t d i s p l a y s employed ( m o t i o n v e r s u s s t a -t i o n a r y ) were s t a t i s t i c a l l y r e l i a b l e . To f a c i l i t a t e i n t e r p r e t a t i o n o f t h e r e s u l t s t h e d a t a were combined f o r - t h i s f a c t o r and r e a n a l y s e d . The r e s u l t s o f t h i s a n a l y s i s - a r e p r e s e n t e d i n - T a b l e 13 o f Appendix"A and the means f o r each group a r e p r e s e n t e d i n F i g u r e r22. The l e s i o n groups d i f f e r e d i n r a t e o f a c q u i s i t i o n o f t h e r e s p o n s e ( F = 3.21; d f = 3, 105; £ = .001). The DP l e s i o n e d a n i m a l s d i f f e r e d r e l i a b l y f r o m SH a n i m a l s i n s e s s i o n 2 and t h e DP and SG l e s i o n e d a n i m a l s r e l i a b l y d i f f e r e d f r o m SH a n i m a l s i n s e s s i o n 3- The ST and SP a n i -mals d i d n o t d i f f e r r e l i a b l y f r o m SH a n i m a l s i n any o f t h e s e s e s s i o n s ( D u n n e t t ' s t , <* = .05/2, 5, 35,= 3«4l). The h i s t o l o g i c a l r e s u l t s f o r t h i s s t u d y a r e p r e s e n t e d i n F i g u r e 23. The e x t e n t o f t h e damage i s d e p i c t e d i n r e p r e s e n t a t i v e s e c t i o n s . Damage s u s t a i n e d by t h e a n i m a l s i n ea c h o f t h e l e s i o n groups was as e x t e n s i v e as t h a t r e p o r t e d i n t h e p r e c e d i n g s t u d i e s . 92 A. F i g u r e 22(a-e). Mean number o f l i c k s d u r i n g t h e 5 sec b a s e l i n e (B) and d u r i n g t h e p r e s e n t a t i o n o f t h e s t i m u l u s ( S ) w h i c h was f o l -l o w e d by an u n a v o i d a b l e f o o t s h o c k , ( a ) SH, (b) ST, ( c ) SC, ( d ) SP and (e) DP l e s i o n e d a n i m a l s . •a z6 93 A . F i g u r e 23 (A-D). R e p r e s e n t a t i v e s e c t i o n s d e p i c t i n g t h e e x t e n t o f damage t o SC and s u r r o u n d i n g t i s s u e f o r ( A ) SC, ( B ) SP, (c) DP and (D) a s u r f a c e v i e w o f c o r t i c a l damage and c o r r e s p o n d i n g t h a l a m i c degen-e r a t i o n f o r ST l e s i o n e d a n i m a l s . The s m a l l e s t l e s i o n a t each r e p r e -s e n t a t i v e s e c t i o n i s drawn i n "black and t h e l a r g e s t i s s t i p p l e d . 93 B. The SG lesions always included damage to the superficial and deep layers of the SG, pretectal nuclei, branchium of SG, dorsal tegmen-tum, -.and overlying white matter of the cortex. Some of the animals i n this group also sustained damage to the central grey and hippo-campus. The SP lesions were restricted primarily to the superficial layers of SC and a l l the lesions damaged the branchium of SC. The DP lesions were confined to the lateral edge of the deep layers of SC and dorsal tegmentum. The ST lesions varied i n size and placement for the animals i n this study. Half the animals had lesions confined primarily to area 17 and the remainder had lesions which included damage to area 17, 18, 18A,and 7« The behavioral results varied markedly depending upon the extent of the lesions. Animals with lesions confined to a small portion of area 17, or.all.of area 17 and small portions of the bordering areas 18, 18A, and 7 did not d i f f e r from SH animals on the t r i a l s to criterion measure or when the data from the f i r s t 4 sessions were analysed. The rats with extensive damage to area 17, 18, 18A, and 7 required many more t r i a l s to reach the suppression criterion. These animals did not, however, di f f e r from SH animals during the f i r s t k sessions but did require more t r i a l s to reach the s t r i c t performance criterion of almost perfect suppression. 9 5. D i s c u s s i o n These d a t a a g a i n d e m o n s t r a t e t h a t SG l e s i o n e d a n i m a l s a r e -not b l i n d t o t h e v i s u a l d i s p l a y s .that they- v^no-^ed;'4n-_..tfe-i-.pt.ey^u^ e x ^ p e r i m e n t s a n d ' i n phase 1 .of .the. 'pE.es-e.nt --expe^i^ent.,:'.' /Al'.l • tfi£- a.n$ma,ls-d i s r u p t e d l i c k i n g when t h e l i g h t s were f o l l o w e d b y an u n a v o i d a b l e f o o t s h o c k . The t h i r s t y SP and DP l e s i o n e d a n i m a l s , i n f a c t , r e q u i r e d f e w e r t r i a l s t o r e a c h a r a t h e r s t r i c t p e r f o r m a n c e c r i t e r i o n o f a l m o s t p e r f e c t s u p p r e s s i o n o f l i c k i n g i n t h e p r e s e n c e o f t h e l i g h t s . The a c c e l e r a t e d a c q u i s i t i o n o f c r i t e r i o n p e r f o r m a n c e by t h e SG and DP l e s i o n e d a n i m a l s may-be due ' t o d i f f e r e n t i a l s e n s i t i v i t y t o t h e sh o c k o r t o t h e d e p r i v a t i o n o f t h e s e a n i m a l s . M a n i p u l a t i o n o f d e p r i v a t i o n and sh o c k i n t e n s i t y do a f f e c t t h e a c q u i s i t i o n o f c o n d i -t i o n e d s u p p r e s s i o n f o r i n t a c t a n i m a l s ( M a c k i n t o s h , 1977)• The i n f l u -ence o f t h e s e v a r i a b l e s c a n not./ o f c o u r s e , be e l i m i n a t e d s i n c e t h e DP l e s i o n e d a n i m a l s d i d r e q u i r e s u p p l e m e n t a l a c c e s s t o a d d i t i o n a l w a t e r t o m a i n t a i n body w e i g h t comparable t o t h e SH c o n t r o l a n i m a l s a n d the SC l e s i o n s damaged t h e p r o p r i o c e p t i v e f i b e r s o f t h e c e n t r a l g r e y t h o u g h t t o be i n v o l v e d i n r e s p o n s e s t o p a i n f u l s t i m u l i (Marx, 1976). A s e p a r a t e a n a l y s i s o f t h e SC and DP l e s i o n e d a n i m a l s ' d a t a does.,, however, s u g g e s t s a n o t h e r - i n t e r p r e t a t i o n . I t - i s p o s s i b l e t h a t t h e enhanced a c q u i s i t i o n o f s u p p r e s s i o n was r e l a t e d t o t h e f a c t t h a t SC and DP l e s i o n e d a n i m a l s d i d n o t o r i e n t t o t h e l i g h t d i s p l a y d u r i n g phase 1 o f t h e e x p e r i m e n t . An e x a m i n a t i o n o f t h e i m p o r t a n c e o f o r i e n t i n g d u r i n g phase 1 o f t h e e x p e r i m e n t on t h e a c q u i s i t i o n 96-o f c o n d i t i o n e d s u p p r e s s i o n was p r o v i d e d by c o m p a r i n g t h e r e s u l t s f o r t h e a n i m a l s who d i d n o t o r i e n t i n phase 1 o f t h i s s t u d y w i t h t h o s e who d i d ( t e s t e d i n E x p e r i m e n t V and r e p o r t e d i n . A p p e n d i x B ) . The r e s u l t s o f t h i s c o m p a r i s o n s u g g e s t e d a t r e n d towards f a s t e r a c q u i s i -t i o n o f s u p p r e s s i o n t o t h e l i g h t s by t h e a n i m a l s who d i d n o t o r i e n t t o them i n phase 1. The e f f e c t , however, a p p r o a c h e d b u t d i d n o t a t t a i n c o n v e n t i o n a l s t a t i s t i c a l r e l i a b i l i t y ( F = 1.92; d f = 9, £ = .055). An e x p e r i m e n t c u r r e n t l y i n p r o g r e s s a l s o examines t h i s q u e s t i o n . T h i s e x p e r i m e n t i n v o l v e s a c o m p a r i s o n o f t h e r a t e o f a c q u i s i t i o n o f s u p p r e s s i o n t o t h e a p p a r e n t l y moving l i g h t d i s p l a y w i t h t h e a p p r o a c h i n g l i g h t d i s p l a y . P r e l i m i n a r y r e s u l t s s u g g e s t t h a t the enhanced a c q u i s i t i o n o f c r i t e r i o n p e r f o r m a n c e b y SC a n d DP l e s i o n e d a n i m a l s c o r r e l a t e d w i t h the absence o f o r i e n t i n g t o t h e l i g h t d i s p l a y d u r i n g p r e - e x p o s u r e o f t h e a p p a r e n t l y moving s t i m u l u s d i s p l a y i n phase 1. I f t h e a n i m a l s o r i e n t e d t o t h e l i g h t d i s p l a y ( a p p r o a c h i n g l i g h t s ) i n phase 1, a c q u i s i t i o n o f c r i t e r i o n p e r f o r m a n c e was n o t enhanced and was e q u i v a l e n t t o t h e SH c o n t r o l a n i m a l s . These f i n d i n g s a r e o n l y p r e l i m i n a r y b u t have . i n t e r e s t i n g i m p l i c a t i o n s w i t h r e s p e c t t o t h e r e l a t i o n s h i p between t h e o r i e n t i n g r e s p o n s e and o t h e r v i s u a l l y g u i d e d b e h a v i o r s . The t h r u s t o f t h e p r e s e n t r e p o r t , however, was t o d e t e r m i n e i f SC l e s i o n e d r a t s were c a p a b l e o f u s i n g a s t i m u l u s , w h i c h t h e y d i d n o t r e a d i l y o r i e n t t o , as a s i g n a l o f shock. The r e s u l t s d e m o n s t r a t e t h a t t h e s e a n i m a l s were c a p a b l e o f u s i n g a v i s u a l d i s p l a y as a s i g n a l o f s h o c k even t h o u g h t h e y had i g n o r e d t h e l i g h t d i s p l a y p r i o r t o i t b e i n g p a i r e d w i t h shock. F u r t h e r , t h e SC and DP l e s i o n e d a n i m a l s a c q u i r e d t h i s r e s p o n s e i n f e w e r t r i a l s t h a n t h e SH c o n t r o l s . ' A c c e l e r a t e d a c q u i s i -t i o n o f c o n d i t i o n e d s u p p r e s s i o n may be r e l a t e d t o t h e absence o f o r i e n t i n g d u r i n g p r e - e x p o s u r e o f t h e l i g h t d i s p l a y s b u t t h i s r e l a t i o : s h i p w i l l r e q u i r e f u r t h e r i n v e s t i g a t i o n . GENERAL -DISCUSSION The p a r a m e t e r s o f o r i e n t i n g The o r i e n t i n g r e s p o n s e g e h e r a l l y i s h a s been t r e a t e d as a s i m p l e r e f l e x i v e and u n i t a r y b e h a v i o r w h i c h o c c u r s i n r e s p o n s e t o the' p r e s e n t a t i o n o f a l m o s t any s t i m u l u s . An a n i m a l , however, c a n n o t and does n o t r e s p o n d t o a l l s t i m u l u s changes. R a t h e r , o r i e n t i n g i s a s e l e c t i v e b e h a v i o r and t h i s s e l e c t i v i t y i s d e t e r m i n e d by a number o f p a r a m e t e r s i n t r i n s i c and e x t r i n s i c t o t h e a n i m a l . F u r t h e r , o r i e n t i n g i s c o m p r i s e d o f a s e r i e s o f b e h a v i o r a l components. A d e s -c r i p t i o n o f t h e o r i e n t i n g r e s p o n s e t o a v i s u a l s t i m u l u s i n c l u d e s t h e c e s s a t i o n o f o n g o i n g b e h a v i o r , t h e eye, head,and p o s t u r a l a d j u s t -ments r e q u i r e d t o l o c a l i z e and f i x a t e t h e s t i m u l u s , and t h e r e a c h i n g , t r a c k i n g , a n d l o c o m o t o r a c t i o n s made towa r d s the s t a t i o n a r y o r moving s t i m u l u s . These b e h a v i o r a l components a r e o n l y subsumed by t h e gen-e r a l t e r m " o r i e n t i n g " when t h e y o c c u r i n a sequence. Each component o f t h i s sequence, i n f a c t , r e p r e s e n t s a d i s c r e t e r e s p o n s e . The p a r a m e t e r s w h i c h i n f l u e n c e o r i e n t i n g a p p e a r t o have t h e i r e f f e c t on t h e d u r a t i o n d f each component and wh e t h e r o r n o t t h e e n t i r e sequence o f b e h a v i o r s o c c u r s . An a t t e m p t was made t o d e t e r m i n e i f t h e e n t i r e sequence o f b e h a v i o r s i n v o l v e d i n o r i e n t i n g o c c u r r e d i n r e s p o n s e t o t h e s t i m u l i employed i n t h i s i n v e s t i g a t i o n by o b s e r v i n g t h e a n i m a l s on t h e f i r s t t r i a l . D i s r u p t i o n o f o n g o i n g b e h a v i o r was, however, t h e p r i m a r y mea-s u r e u s e d i n t h i s i n v e s t i g a t i o n ' s t h i s component o f t h e r e s p o n s e 99 i s n e c e s s a r y i f t h e o t h e r components of t h e sequence a r e t o o c c u r . A n o v e l s t i m u l u s c a n i n f l u e n c e o r g a i n c o n t r o l o f subsequent b e h a v i o r s o n l y i f t h e a n i m a l d i s r u p t s i t s o n g o i n g b e h a v i o r ( i . e . , s h i f t s i t s a t t e n t i o n ) . P r e v i o u s c o n c l u s i o n s t h a t SC l e s i o n e d a n i m a l s were i n c a p a b l e o f t h e o r i e n t i n g r e s p o n s e have been b a s e d on paradigms t h a t i g n o r e , t h e d i s r u p t i o n component o f t h e o r i e n t i n g r e s p o n s e and r e q u i r e , t h e a n i -mals t o l o c a l i z e and engage i n p r o l o n g e d e x p l o r a t i o n , o f t h e v i s u a l s t i m u l u s ( K i r v e l e t a l . , 1974; S c h n e i d e r , 1967, 1969). These s t u d i e s d i d n o t t a k e i n t o c o n s i d e r a t i o n t h e f a c t t h a t t h e o r i e n t i n g r e s p o n s e i s a sequence o f b e h a v i o r s i n v o l v i n g s e v e r a l components and have i n a p p r o p r i a t e l y c o n c l u d e d t h a t o r i e n t i n g was a b s e n t because t h e l a s t component d i d n o t o c c u r . W i l k i e a n d Masson (1976) have made a s i m i l a r argument w i t h r e s p e c t t o s t u d i e s o f a t t e n t i o n . (See Note 1.) W h i l e t h e p a r a d i g m u s e d i n t h i s s t u d y d i d n o t r e q u i r e t he a n i m a l s t o l o c a l i z e o r e x p l o r e t h e s t i m u l u s , i t was s e n s i t i v e t o s m a l l b u t r e l i a b l e r e s p o n s e s t o t h e l i g h t d i s p l a y s . Some o f t h e l i g h t d i s p l a y s employed i n t h i s . i n v e s t i g a t i o n c l e a r l y - . c o n t r o l l e d t h e SC l e s i o n e d a n i m a l s ' b e h a v i o r . The l o c a l i z a t i o n and e x p l o r a t i o n component o f t h e o r i e n t i n g r e s p o n s e were o f t e n so b r i e f t h a t a measure b a s e d o n l y on o b s e r v a t i o n o f t h e a n i m a l s ' eye, head, and p o s t u r a l a d j u s t m e n t s would have been d i f f i c u l t t o o b t a i n . M a n i p u l a t i o n o f s t i m u l u s c h a r a c t e r i s t i c s and i n t r i n s i c p a r a m e t e r s had- t h e i r e f f e c t on two f a c e t s o f o r i e n t i n g b e h a v i o r . These were t h e amount o f d i s r u p t i o n o f l i c k i n g on each t r i a l and 100 t h e number o f p r e s e n t a t i o n s o f t h e l i g h t d i s p l a y s t h a t r e s u l t e d i n a r e l i a b l e r e s p o n s e ( i . e . , t h e r a t e o f h a b i t u a t i o n ) . W h i l e s y s t e m a t i c measurement o f t h e o c c u r r e n c e and d u r a t i o n o f a l l t h e components o f o r i e n t i n g was n o t t h e p u r p o s e o f t h i s i n v e s t i g a t i o n , o b s e r v a t i o n o f t h e a n i m a l s ' r e s p o n s e t o t h e l i g h t d i s p l a y r e v e a l e d t h a t t h e s t i m u -l u s c h a r a c t e r i s t i c s a f f e c t e d whether any o r a l l o f t h e components o f t h e o r i e n t i n g r e s p o n s e o c c u r r e d ( i . e . , d i s r u p t i o n , l o c a l i z a t i o n and e x p l o r a t i o n ) and t h e d u r a t i o n o f e ach component. The amount o f d i s r u p t i o n o f l i c k i n g was c l o s e l y c o r r e l a t e d w i t h t h e amount o f t i m e t h e SH a n i m a l s a c t u a l l y engaged i n t h e v a r i -ous components o f t h e o r i e n t i n g r e s p o n s e on t h e f i r s t t r i a l . T h i s c o r r e l a t i o n , however, was n o t p e r f e c t . I n a d d i t i o n , o b s e r v a -t i o n o f t h e a n i m a l s ' h a b i t u a t i o n t o t h e l i g h t d i s p l a y s r e v e a l e d t h a t e x p l o r a t o r y b e h a v i o r s t o w a r d s t h e l i g h t s c e a s e d f i r s t , t h e n l o c a l i z a t i o n o f t h e l i g h t s , a n d , f i n a l l y , d i s r u p t i o n o f l i c k i n g c e a s e d . A l l t h e s t i m u l u s d i m e n s i o n s examined e l i c i t e d t h e o r i e n t i n g r e s p o n s e f r o m t h e SH a n i m a l s and t h e amount o f d i s r u p t i o n o f l i c k i n g t o t h e v a r i o u s l i g h t d i s p l a y s on t h e e a r l y t r i a l s was n o t m a r k e d l y d i f f e r e n t . R e s p o n d i n g t o t h e d i s p l a y s c a n , however, be r a n k e d i n terms o f r a t e o f h a b i t u a t i o n . The o r d e r f r o m l o w e s t t o h i g h e s t r a t e o f h a b i t u a t i o n was: t h e ' " s o l i d " n i n e l i g h t d i s p l a y , t h e " c i r c l i n g " d i s p l a y , t h e " s t a t i o n a r y " d i s p l a y , t h e "moving" d i s p l a y , and t h e " a p p r o a c h i n g " d i s p l a y . The s a l i e n c e o f t h e d i s p l a y s a p p e a r e d t o r e s u l t f r o m a c o m b i n a t i o n o f s t i m u l u s c h a r a c t e r i s t i c s . The amount o f r e s p o n d i n g 101. e l i c i t e d b y a p a r t i c u l a r d i s p l a y was n o t d e t e r m i n e d s o l e l y by t h e i n t e n s i t y o r a b s o l u t e number o f changes, t h e amount o f a c t i v i t y i n t h e d i s p l a y , i n c l u s i o n o f a p p a r e n t m o t i o n , o r t h e d i s t a n c e o f t h e a p p a r e n t m o t i o n . F o r example, t h e a p p r o a c h i n g l i g h t s ( E x p e r i m e n t I V ) were more e f f e c t i v e t h a n t h e moving l i g h t s ( E x p e r i m e n t i ) , even though t h e i n t e n s i t y and amount o f a c t i v i t y i n v o l v e d i n t h i s d i s p l a y were l e s s . The p a t t e r n o r s p a t i a l c o n f i g u r a t i o n o f t h e l i g h t s i n t h e d i s p l a y c l e a r l y i n f l u e n c e d t h e s a l i e n c e o f t h e d i s p l a y f o r SH a n i -mals and s h o u l d be i n c l u d e d as a p a r a m e t e r o r d e t e r m i n a n t o f o r i e n t i n g b e h a v i o r ( E x p e r i m e n t I V ) . I n a s i m i l a r manner, t h e o c c u r r e n c e o f and magnitude o f d i s h a b i t u a t i o n t o changes i n the l i g h t d i s p l a y s a p p e a r e d t o r e s u l t f r o m a c o m b i n a t i o n o f f a c t o r s i n c l u d i n g : t h e i n t e n s i t y , m o t i o n , and t h e s p e c i f i c p a t t e r n o f t h e d i s p l a y . F o r example, t h e change i n t h e d i r e c t i o n o f t h e a p p r o a c h i n g t o r e c e d i n g l i g h t s more r e l i a b l y e l i c i t e d d i s h a b i t u a t i o n ( E x p e r i m e n t I V ) t h a n t h e change f r o m t h e moving t o the s t a t i o n a r y l i g h t s ( E x p e r i m e n t i ) . The e f f e c t s o f SG l e s i o n s on o r i e n t i n g The SG l e s i o n e d a n i m a l s d i d n o t o r i e n t t o a " f l i c k e r i n g " o r " a p p a r e n t l y " moving s t i m u l u s . These s t i m u l u s d i s p l a y s were q u i t e s a l i e n t f o r SH a n i m a l s and r e q u i r e d a number o f p r e s e n t a t i o n s f o r h a b i t u a t i o n t o o c c u r . The e l i m i n a t i o n o f o r i e n t i n g t o t h e s e s t i m u l i by t h e SC l e s i o n e d a n i m a l s c o u l d n o t be a t t r i b u t e d t o a g e n e r a l i n a b i l i t y t o d i s r u p t o r s h i f t t h e d i r e c t i o n o f t h e i r b e h a v i o r . These same a n i m a l s c l e a r l y c e a s e d l i c k i n g when an a u d i t o r y s t i m u l u s was p r e s e n t e d and l o c a l i z e d t h e s o u r c e o f t h e t o n e ( E x p e r i -ment I I ) . The SC l e s i o n e d a n i m a l s a l s o o r i e n t e d t o t h e l i g h t s when t h e p h y s i c a l i n t e n s i t y o f t h e d i s p l a y was i n c r e a s e d ( E x p e r i m e n t I I I ) o r when a d i f f e r e n t p a t t e r n o f t h e d i s p l a y was employed ( E x p e r i m e n t I V ) . F u r t h e r , t h e SC l e s i o n e d a n i m a l s were shown t o he c a p a b l e o f o r i e n t i n g t o t h e p r e v i o u s l y i g n o r e d l i g h t d i s p l a y when g i v e n a c c e s s t o w a t e r p r i o r t o t e s t i n g ( E x p e r i m e n t .V.) and d i s r u p t e d l i c k i n g when I t . w a s p a i r e d w i t h s h o c k ( E x p e r i m e n t V i ) . Even though t h e SC l e s i o n e d a n i m a l s d i d o r i e n t t o some o f t h e v i s u a l d i s p l a y s t h e i r b e h a v i o r d i f f e r e d f r o m t h a t o f t h e SH con-t r o l a n i m a l s i n t h r e e ways: ( l ) The amount o f d i s r u p t i o n o f l i c k i n g i n r e s p o n s e t o t h e l i g h t s and t h e number o f t r i a l s t o h a b i t u a t e t o d i f f e r e n t d i s p l a y s d i f f e r e d m a r k e d l y between t h e SC and SH l e s i o n e d a n i m a l s . A l l t h e SC l e s i o n e d a n i m a l s h a b i t u a t e d more q u i c k l y t o t h e r e p e a t e d p r e s e n t a t i o n o f t h e v i s u a l d i s p l a y s t h a n t h e SH a n i m a l s and t h e y g e n e r a l l y d i d not d i s h a b i t u a t e t o t h e changes i n t h e v i s u a l d i s -p l a y s . (2) When SC l e s i o n e d a n i m a l s o r i e n t e d t o t h e l e s s s a l i e n t d i s p l a y s , o n l y t h e d i s r u p t i o n and l o c a l i z a t i o n components were o b s e r v e d and t h e s e were o f r e d u c e d d u r a t i o n r e l a t i v e t o t h o s e o f con-t r o l a n i m a l s . O r i e n t i n g t o t h e more s a l i e n t d i s p l a y s a l s o i n v o l v e d o n l y t h e d i s r u p t i o n and l o c a l i z a t i o n components f o r t h e SC l e s i o n e d a n i m a l s a l t h o u g h t h e d u r a t i o n s o f t h e s e components were p r o l o n g e d r e l a t i v e t o t h e l e s s s a l i e n t d i s p l a y s . (3) U n l i k e c o n t r o l a n i m a l s , SC l e s i o n e d a n i m a l s were n e v e r o b s e r v e d t o approach t h e l i g h t d i s -p l a y o r t o f o l l o w t h e a p p a r e n t m o t i o n o f t h e d i s p l a y . 103 The " b e h a v i o r a l - d e f i c i t d e m o n s t r a t e d by SG l e s i o n e d a n i m a l s c a n be summarized as v i s u a l " n e g l e c t " o r " i n a t t e n t i o n " t o n o v e l v i s u a l s t i m u l i w h i c h c a p t u r e t h e n o r m a l - a n i m a l s ' a t t e n t i o n and provoke a "dramatic,"-reaction-." " . T r a d i t i o n a l models .of t h e n e u r a l - b a s i s o f v i s u a l l y g u i d e d b e h a v i o r have s u g g e s t e d a d i r e c t r e l a t i o n s h i p between " t h e " o r i e n t i n g r e s p o n s e and the SG. These models f u r t h e r s u g g e s t e d t h a t t h e SC was e s s e n t i a l t o t h e e l i c i t a t i o n o f o r i e n t i n g . C l e a r l y , t h e SC need n o t be i n t a c t f o r a v i s u a l s t i m u l u s t o e l i c i t t h e d i s r u p t i o n o f o n g o i n g b e h a v i o r and t h e l o c a l i z a t i o n o f a s t i m u l u s . S u p e r i o r c o l l i c u l u s l e s i o n s d i d r e s u l t i n an i m p a i r m e n t o f o r i e n t i n g b e h a v i o r i n terms o f t h e d u r a t i o n o f t h e s e components, t h e r a t e o f h a b i t u a t i o n o f o r i e n t i n g , and d i s h a b i t u a t i o n t o changes i n v i s u a l s t i m u l i . I n summary, t h e SC l e s i o n e d a n i m a l s were o n l y " l e s s " r e s p o n -s i v e t o n o v e l v i s u a l s t i m u l i , b u t n o t i n c a p a b l e o f o r i e n t i n g . Gasagrande and Diamond (1974) and Sprague e t a l . (1977) a l s o s u g g e s t e d t h a t SG l e s i o n e d a n i m a l s m a n i f e s t a b e h a v i o r a l d e f i c i t w h i c h t h e y d e s c r i b e d as v i s u a l n e g l e c t o r i n a t t e n t i o n . The s t u d i e s i n c l u d e d i n t h i s r e p o r t a r e c o n s i s t e n t w i t h o t h i s i n t e r p r e t a t i o n - , however, t h e f i n d i n g s emphasize t h e f a c t t h a t v i s u a l n e g l e c t o r i n a t t e n t i o n need n o t r e f l e c t a n i n a b i l i t y t o o r i e n t o r r e s p o n d t o v i s u a l s t i m u l i . The v i s u a l n e g l e c t o r i n a t t e n t i o n , m a n i f e s t e d " by SC l e s i o n e d r a t s was s e l e c t i v e and a p p e a r e d t o r e p r e s e n t a q u a n t i t a t i v e change i n t h e a n i m a l s ' r e s p o n s e t o n o v e l s t i m u l i a n d t o changes i n v i s u a l s t i m u l i . 104 The animals were not simply inactive and unresponsive to stimuli or change per se. This point i s clearly illustrated by the following findings: (l) SG lesioned animals did not d i f f e r from SH animals in response to an auditory stimulus. (2) Manipulation of the amount of water accessible to the animals prior to testing resulted in disruption of licking equivalent to that of the intact animals. (3) The SC and DP lesioned animals were capable of using the onset of the previously ignored light displays as a signal of shock, and further, they acquired this response in less t r i a l s than SH animals. (4) Finally, the SC and DP lesioned animals were much more active than SH animals tested in an open f i e l d situation. These results are reported in Appendix D. The SC and DP lesioned animals crossed more squares in the f i e l d and reared less often than SH animals. The SC lesioned animals' excessive activity in the open f i e l d appeared to be due in part to the fact that they were not distracted by the peripheral stimuli which the intact animals appeared to respond to by rearing and sniffing, but instead, persisted i n their locomotor activity. These results supplemented the interpretation outlined above and clearly demonstrated that SC lesioned animals did not suffer a general malaise which would have interfered with their responsiveness to visual stimuli. The data reported above suggest that the selective visual neglect or inattention demonstrated by SC lesioned animals did not result from a simple, passive neglect of visual stimuli. Rather, the animals were less easily distracted by the less salient stimuli 105 i n t h e i r e n v i r o n m e n t and d i d n o t s h i f t o r r e d i r e c t t h e i r b e h a v i o r ( o r a t t e n t i o n ) t o t h e l i g h t s and n e g l e c t t h e w a t e r s p o u t . The p e r s i s t e n c e o f t h e SG and DP l e s i o n e d a n i m a l s i n t h e open f i e l d and enhanced r a t e o f a c q u i s i t i o n o f s u p p r e s s i o n t o t h e l i g h t s when p a i r e d w i t h s h o c k sup-p o r t t h i s i n t e r p r e t a t i o n . R e s u l t s o f o t h e r s t u d i e s a r e a l s o c o n s i s t e n t w i t h t h i s i n t e r p r e t a t i o n . Jane," L e v e y , and G a r l s o n (1972) d e m o n s t r a t e d t t t t h a t SC l e s i o n e d a n i m a l s had d i f f i c u l t y w i t h r e v e r s a l s i n a p a t t e r n d i s -c r i m i n a t i o n t a s k and p e r s i s t e d i n r e s p o n d i n g t o t h e p r e v i o u s l y r e w a r d e d s t i m u l i . Goodale and M u i r i s o n (1975) f o u n d t h a t SG a n i m a l s t o o k more d i r e c t p a t h s t o a g o a l box t h a n c o n t r o l a n i m a l s and were n o t d i s t r a c t e d by i r r e l e v a n t v i s u a l and a u d i t o r y s t i m u l i . A l s o , r a t s w i t h SG l e s i o n s d i d n o t d i s r u p t b a r p r e s s i n g when an i r r e l e v a n t l i g h t was p r e s e n t e d ( G o o d a l e & L i s t e r , 1974), and were l e s s s u s c e p t i b l e t o a s t a r t l i n g s t i m u l u s t h a n c o n t r o l s ( G o o d a l e , M i l n e r & Rose, 1975)- More r e c e n t l y , G o o d a l e , Foreman, and M i l n e r (1977) f o u n d t h a t v i s u a l n e g l e c t o f i r r e l -e v a n t , d i s t r a c t i n g , and n o v e l s t i m u l i was r e s t r i c t e d t o t h e p e r i p h e r y o f t h e v i s u a l f i e l d s i n c o l l i c u l e c t o m i z e d r a t s . These a n i m a l s were, however, d i s t r a c t e d by an i r r e l e v a n t s t i m u l u s when i t was p r e s e n t e d i n t h e c e n t r a l v i s u a l f i e l d i n c l o s e r p r o x i m i t y t o t h e g o a l box. The s a l i e n c e o f a v i s u a l s t i m u l u s and i t s p o t e n t i a l t o be d i s t r a c t i n g a r e l i k e l y a f u n c t i o n o f i t s p o s i t i o n i n t h e v i s u a l f i e l d , i t s p r i o r a s s o -c i a t i o n w i t h a v e r s i v e o r r e w a r d i n g consequences, and t h e o t h e r e x t r i n -s i c p a r a m e t e r s o u t l i n e d i n t h i s r e p o r t . These v a r i a b l e s w a r r a n t f u r -t h e r s y s t e m a t i c measurement t o d e t e r m i n e t h e i r r e l a t i v e c o n t r i b u t i o n as p a r a m e t e r s o f t h e o r i e n t i n g r e s p o n s e . 106. The e f f e c t o f l e s i o n s o f t h e s u p e r f i c i a l and deep l a m i n a e o f t h e  SG on o r i e n t i n g . L e s i o n s o f t h e e n t i r e SC r e s u l t e d i n " n e g l e c t " o r " i n a t -t e n t i o n " t o a l i g h t d i s p l a y t h a t n o r m a l a n i m a l s r e s p o n d e d t o . When t h e l e s i o n s were c o n f i n e d t o o n l y a s m a l l a r e a a t t h e j u n c t i o n o f t h e deep l a y e r s o f t h e SC and t h e a d j a c e n t d o r s a l tegmentum, v i s u a l n e g l e c t was a l s o d e m o n s t r a t e d . As was t h e case f o r a n i m a l s w i t h l e s i o n s o f t h e e n t i r e SC, l e s i o n s o f t h e deep l a m i n a e d i d n o t com-p l e t e l y e l i m i n a t e o r i e n t i n g b e h a v i o r . These a n i m a l s d i s r u p t e d l i c k i n g and l o c a l i z e d t h e more s a l i e n t l i g h t d i s p l a y s . When l e s s t h i r s t y , t h e y o r i e n t e d t o and l o c a l i z e d a l i g h t d i s p l a y t h e y p r e v i o u s l y i g n o r e d and t h e y r e s p o n d e d t o t h i s d i s p l a y as a s i g n a l when i t was p a i r e d w i t h s h o c k . U n l i k e t h e a n i m a l s w i t h l e s i o n s o f t h e deep l a m i n a e o r t h e e n t i r e SC, a n i m a l s w i t h l e s i o n s c o n f i n e d t o o n l y t h e s u p e r f i c i a l l a m i n a e o f t h e SC and t h e b r a n c h i u m o f t h e SC o r i e n t e d t o and l o c a l i z e d a l l o f t h e n o v e l v i s u a l d i s p l a y s . R e c e n t l y , i t has been p o p u l a r t o a t t e m p t t o d i s s o c i a t e t h e r o l e o f t h e s u p e r f i c i a l l a m i n a e and t h e deep l a m i n a e o f t h e SC as d i s c r e t e f u n c t i o n a l and a n a t o m i c a l systems (Casagrande & Diamond, 1974; I n g l e & Spra g u e , 1974). Casagrande and Diamond a l s o f o u n d t h a t l e s i o n s c o n f i n e d t o t h e s u p e r f i c i a l l a m i n a e d i d n o t i n t e r f e r e w i t h o r i e n t i n g t o v i s u a l s t i m u l i b y t r e e shrews. "However, l e s i o n s t h a t i n c l u d e d b o t h t h e s u p e r f i c i a l and deep l a y e r s d i d . They s u g -g e s t e d t h a t t h e s u p e r f i c i a l l a y e r s • w e r e not. i n v o l v e d i n o r i e n t i n g b e h a v i o r e x c e p t as t h e s o u r c e o f v i s u a l i n f o r m a t i o n t o t h e deep 107 layers of the colliculus. It was the deep layers in conjunction with other (presumably non-visual) inputs that were responsible for i n i t i a t i n g the orienting response to visual stimuli. The data presented in this report support this interpreta^ tion i f one considers only the less salient light displays (which the DP lesioned animals did not orient to while the SP lesioned animals did). It is also interesting in this regard that the SP and DP lesioned animals differed with respect to their performance in the open f i e l d and acquisition of the visual display-shock-'.associa-tion. The SP lesioned animals did not d i f f e r from the SH operated controls in either of these tasks, while the DP lesioned animals were more active,in the open f i e l d and acquired the visual display-shock association faster than SH operated controls. However, other data are not supportive of Casagrande and Diamond's interpretation, since: (l) Orienting to the more salient displays was not eliminated for the DP lesioned animals and, in r e s -ponse to these displays, they behaved l i k e the SP lesioned animals. ( 2 ) The DP and-SP lesioned animals were also alike in that they gen-erally did not dishabituate to the changes in the lig h t displays. Finally, ( 3 ) the DP and SP lesioned animals did not rear in the open f i e l d , nor were they observed to engage in the intense explora-tory behavior that SH operated animals demonstrated in response to some of the moving light displays. These data suggest that the superficial and deep laminae of the superior colliculus are not discrete functional and anatomical systems. 108 The effect of "cortical lesions or. orienting Lesions restricted to the striate cortex (area 17)rand the extrastriate cortex (areas 18 & 18A) did not impair orienting, habitua-tion, or dishabituation. These animals were identical to the SH oper-ated control animals in a l l respects. Lesions which included area 7 as well as a l l of areas 17, 18, and 18A did not interfere with the disruption and localization components of the orienting i n response to any of the novel light displays; however, these animals required fewer t r i a l s to habituate to the light displays and did not disha-bituate to the changes in the light displays. Only a few rats, however, sustained a lesion which removed area 7 and a l l of the striate and extrastriate cortex i n this report; consequently, additional animals were tested and the results are reported i n Appendix E. The results of this study confirmed the above findings and demonstrate that lesions of the cortex l i k e l y require the loss of both the geniculo-striate system and the input from the superficial layers of the SG to the cortex (via NLP) to yield a behavioral d e f i c i t comparable to that caused by lesions of the superficial'-'.SC laminae. Lesions of the superficial layers of the SC (SP lesions), the terminal area of the geniculo-striate and tecto-pulvinar system (large cortical lesions), or the geniculo-striate and tecto-pulvinar pathways to cortex (NLP and area 17) do not affect the disruption or localization components of orienting to the novel light displays. However, animals with any of these lesions habituate more quickly and do not dishabituate to the changes in the light dis-plays . 109 On t h e b a s i s o f t h e d a t a summarized above, i t c o u l d be con-c l u d e d t h a t t h e b e h a v i o r a l d e f i c i t o f v i s u a l n e g l e c t o r i n a t t e n t i o n i s s i m p l y a r e s u l t o f t h e r e m o v a l o f t h e deep l a y e r s o f t h e SC. However, i f t h e d i s h a b i t u a t i o n d a t a a r e c o n s i d e r e d i t a p p e a r s t h a t t h e deep l a y e r s o f t h e SC, t h e s u p e r f i c i a l l a y e r s o f t h e SC., and t h e t e r m i n a l a r e a o f t h e g e n i c u l o - s t r i a t e and t e c t o - p u l v i n a r pathways t o t h e c o r t e x a r e a l l i n v o l v e d i n o r i e n t i n g . Indeed, t h e b e h a v i o r s i n v o l v e d i n o r i e n t i n g t o a n o v e l v i s u a l stimulus-.and t h o s e i n v o l v e d i n d i s h a b i t u a t i o n t o changes i n a v i s u a l s t i m u l u s a r e n o t l i k e l y s e p a r a t e b e h a v i o r s . B o t h i n v o l v e t h e r e d i r e c t i o n o f b e h a v i o r t o w a r d s s t i m u l i ( s h i f t s i n a t t e n t i o n ) . D i s h a b i t u a t i o n i s t h e r e c o v e r y o f o r i e n t i n g t h a t o c c u r s i n r e s p o n s e t o changes i n a s t i m u l u s and by d e f i n i t i o n i n v o l v e s s h i f t s i n a t t e n t i o n t o changes w i t h i n a s t i m u l u s m o d a l i t y . I n t h i s i n v e s t i g a t i o n t h e t e r m o r i e n t i n g was r e s t r i c t e d t o t h e d i s r u p t i o n and l o c a l i z a t i o n components w h i c h o c c u r r e d i n r e s -ponse t o t h e n o v e l s t i m u l i on t h e e a r l y t r i a l s . The r e s p o n s e w h i c h o c c u r r e d t o t h e n o v e l s t i m u l i on t h e e a r l y t r i a l s l i k e l y r e p r e s e n t e d a s h i f t i n a t t e n t i o n f r o m a s t i m u l u s o f one m o d a l i t y t o a s t i m u l u s o f a n o t h e r m o d a l i t y ( e . g . , f r o m t h e p r o p r i o c e p t i v e cues i n v o l v e d i n l i c k i n g t h e w a t e r spout t o t h e v i s u a l s t i m u l i ) . L e s i o n s o f t h e c o r t e x and s u p e r f i c i a l l a m i n a e o f t h e SC g e n e r a l l y e l i m i n a t e d d i s h a b i t u a t i o n i n t h i s i n v e s t i g a t i o n . The deep l a y e r s o f t h e SC had t o be i n v o l v e d i n t h e l e s i o n t o e l i m i n a t e o r i e n t i n g t o t h e . n o v e l s t i m u l i . These r e s u l t s may r e f l e c t a d i f f e r -ence i n t h e s e a n i m a l s ' ^ a b i l i t y t o a t t e n d t o changes w i t h i n and 1 10 between m o d a l i t i e s . J a n e e t a l . . . (1972) have p r o p o s e d a s i m i l a r i n t e r p r e t a t i o n with, r e s p e c t t o a t t e n t i o n a l b e h a v i o r . They s u g g e s t e d t h a t i n t r a n o d a l a t t e n t i o n i s m e d i a t e d by t h e c o r t e x w h i l e i n t e r m o d a l a t t e n t i o n i s m e d i a t e d by t h e c o l l i c u l u s . The d a t a , o f t h e - p r e s e n t i n v e s t i g a t i o n , however, s u g g e s t t h a t i n t e r m o d a l a t t e n t i o n i n v o l v e s t h e c o n n e c t i o n s between t h e s t r i a t e , e x t r a s t r i a t e c o r t e x , and s u p e r f i -c i a l l a y e r s o f t h e c o l l i c u l u s . The deep l a y e r s a p p e a r t o be i n v o l v e d i n b o t h i n t e r m o d a l and i n t r a m o d a l a t t e n t i o n . I n t h i s i n v e s t i g a t i o n t h e DP l e s i o n e d a n i m a l s d i d n o t s h i f t f r o m t h e s t i m u l i a s s o c i a t e d w i t h d r i n k i n g t o t h o s e o f t h e v i s u a l d i s p l a y and d i d n o t d i s h a b i t u a t e t o t h e changes i n t h e v i s u a l d i s p l a y . E l e c t r o p h y s i o l o g i c a l r e c o r d i n g s i n o t h e r s p e c i e s ( c a t , Gordon, 1973; mouse, Dr'ager, 1975, 197°; g o l d f i s h , Page & S u t t e r l i n , 1970) a l s o s u g g e s t t h a t an i m p o r t a n t f u n c t i o n o f t h e deep SC l a y e r s may be t h e i n t e g r a t i o n o f i n f o r m a t i o n i n s e v e r a l s e n s e m o d a l i t i e s . C e l l s i n t h e s u p e r f i c i a l l a y e r s o f SC o n l y r e s -pond t o v i s u a l s t i m u l i w h i l e c e l l s i n t h e deep l a y e r s r e s p o n d t o s t i m u l i f r o m e v e r y m o d a l i t y . The f u r t h e r enhancement o f v i s u a l n e g l e c t by i n c l u d i n g t h e deep l a y e r s i n t h e l e s i o n may be t h e r e s u l t o f t h e e l i m i n a t i o n o f t h e v i s u a l i n p u t f r o m t h e s u p e r f i c i a l l a y e r s (and p e r h a p s o t h e r v i s u a l a r e a s ) i n c o m b i n a t i o n w i t h t h e d e s t r u c t i o n o f t h e many c o n v e r g e n t n o n - v i s u a l pathways. The above l e s i o n - b e h a v i o r r e l a t i o n s h i p s a r e summarized i n F i g u r e Zk. T h i s summary s u g g e s t s t h a t a d i f f e r e n t c o n c e p t u a l i z a t i o n o f t h e SC's i n v o l v e m e n t i n o r i e n t i n g i s r e q u i r e d . B e h a v i o r a l l y , I l l A. Figure 24. A schematic diagram of the relationships between the behavioral impairment of orienting and lesions of the visual system. 1 12 s u c h a model would have t o a c c o u n t f o r t h e s e l e c t i v i t y o f o r i e n t i n g b e h a v i o r i n t e r m s o f t h e i n f l u e n c e o f i n t r i n s i c and e x t r i n s i c p a r a -m e t e r s on t h e number o f components o f t h e o r i e n t i n g r e s p o n s e t h a t o c c u r , and t h e d u r a t i o n o f each component. I t was somewhat s u r p r i s i n g t o f i n d t h a t l a r g e l e s i o n s o f c o r t e x o r SC d i d n o t e n t i r e l y e l i m i n a t e o r i e n t i n g b e h a v i o r . I n o t h e r words, n e i t h e r o f t h e " c l a s s i c a l " v i s u a l systems p l a y e d a " p i v o t a l " , r o l e i n t h e d i s r u p t i o n and l o c a l i z a t i o n components o f t h e o r i e n t i n g r e s p o n s e b u t r a t h e r a p p e a r e d t o o n l y m odulate t h e s e b e h a v i -o r s i n t e r m s o f t h e d u r a t i o n o f t h e r e s p o n s e s , r a t e o f h a b i t u a t i o n , d e m o n s t r a t i o n o f d i s h a b i t u a t i o n , and t h e p r o b a b i l i t y o f t h e a n i m a l i n i t i a t i n g f u r t h e r e x p l o r a t o r y a c t i v i t i e s t o w a r d s t h e l i g h t s . Any model o f t h e n e u r a l b a s i s o f o r i e n t i n g b e h a v i o r would have t o i n c l u d e b o t h t h e s u p e r i o r c o l l i c u l u s and t h e t e c t o - p u l v i n a r p r o j e c t i o n s t o c o r t e x i n c o n j u n c t i o n w i t h t h e g e n i c u l o - s t r i a t e p r o j e c t i o n , , as a l l t h e s e pathways a p p e a r t o mod u l a t e o r i e n t i n g b e h a v i o r . T h e r e a r e t h r e e q u e s t i o n s a r i s i n g f r o m t h i s i n v e s t i g a t i o n t h a t w a r r a n t f u r t h e r d i s c u s s i o n and s t u d y : ( l ) What system o r sys t e m s do c o n t r o l t h e f i n a l m o t o r pathways n e c e s s a r y f o r i n i t i a t i o n o f t h e motor r e s p o n s e s i n v o l v e d i n t h e components o f o r i e n t i n g and what i s i t s r e l a t i o n s h i p t o t h e SC? (2) What i s t h e r e l a t i o n s h i p o f t h e SC t o t h e a p p r o a c h and f o l l o w i n g components o f o r i e n t i n g ? (3) What a r e t h e i m p l i c a t i o n s f o r models o f v i s u a l l y g u i d e d b e h a v i o r ? I n i t i a t i o n o f ' o r i e n t i n g The s u p e r i o r c o l l i c u l u s and t h e c o r t e x a p p e a r t o p l a y o n l y m o d u l a t o r y r o l e s i n t h e o r i e n t i n g r e s p o n s e . Hence, t h e n e u r a l a c t i v i t y r e q u i r e d t o i n i t i a t e t h e motor r e s p o n s e s i n v o l v e d i n t h e d i s r u p t i o n and l o c a l i z a t i o n components o f o r i e n t i n g must o c c u r i n : „• - a n o t h e r , n e u r a l s t r u c t u r e ( s ) . The known c o n n e c t i o n s o f t h e r a t 1 s " v i s u a l s y s t e m s " and p o i n t s o f i n t e r a c t i o n a r e p r e s e n t e d i n F i g u r e 24. However, n o t i n c l u d e d i n t h e d i a g r a m a r e o t h e r t e r m i n a l s o f t h e r e t i n a and second o r d e r r e t i n a l c o n n e c t i o n s w h i c h may m e d i a t e t h e d i s r u p t i o n and l o c a l -i z a t i o n components o f o r i e n t i n g (Huhel & W i e s e l , 1977)- Any o f t h e s e s t r u c t u r e s c o u l d he r e s p o n s i b l e f o r t h e i n i t i a t i o n o f t h e d i s r u p t i o n a n d /or l o c a l i z a t i o n components i n v o l v e d i n o r i e n t i n g b e h a v i o r . The v e n t r a l g e n i c u l a t e n u c l e u s , a c c e s s o r y o p t i c n u c l e u s (Hayhow, S e f t o n & Webb, 19°2; Hayhow, Webb & J e r v i e , i960), and i n some s p e c i e s , . e v e n t h e c e r e b e l l u m , r e c e i v e s r e t i n a l i n p u t s (Maekawa & Takeda, 1 9 7 6 ) . A l l t h e s e s t r u c t u r e s have d i r e c t o r i n d i r e c t c o n n e c t i o n s t o t h e SC, t h e tegmentum, o r d i r e c t a c c e s s t o t h e o c u l o m o t o r n u c l e u s and s p i n a l c o r d . The r o l e o f t h e s e s t r u c t u r e s has n o t been i n v e s t i g a t e d t o d a t e . A second p o s s i b i l i t y i s t h a t t h e c o n n e c t i o n s t o t h e o c u l o -motor n u c l e u s and s p i n a l c o r d a r e d u p l i c a t e d t h r o u g h o u t t h e v i s u a l s y s t e m s . A n a t o m i c a l l y t h i s i s c e r t a i n l y f e a s i b l e . The v i s u a l l y r e s p o n s i v e a r e a s o f c o r t e x have numerous c o n n e c t i o n s t o s p i n a l c o r d and m u l t i p l e i n d i r e c t p r o j e c t i o n s t o t h e o c u l o m o t o r n u c l e u s . I n a d d i t i o n , a number o f t h a l a m i c n u c l e i i n o t h e r s p e c i e s r e c e i v e 1 14 d i r e c t p r o j e c t i o n s f r o m r e t i n a and t h e s e n u c l e i i n t u r n p r o j e c t t o t h e o c u l o m o t o r and s p i n a l t r a c t s ( C a s t i g l i o n i , G a l l o w a y , & C o u l t e r , 1 9 7 8 ; Edwards & H e n k e l , 1 9 7 8 ; G o u l d H a l l ,-"& Eb n e r , 1 9 7 8 ) . A model o f o r i e n t i n g m ight i n c l u d e some o r a l l o f t h e s e c o n n e c t i o n s as i n i t i a t i n g n e u r a l commands t o t h e motor mechanisms n e c e s s a r y t o d i s r u p t o n g o i n g a c t i v i t y i n r e s p o n s e t o a s t i m u l u s o r s t i m u l u s change (.-the d i s r u p t i o n component)., The d u r a t i o n o f d i s r u p -t i o n o f o n g o i n g b e h a v i o r and t h e i n i t i a t i o n o f f u r t h e r a c t i v i t y d i r e c t e d t o w a r d s t h e s t i m u l u s may depend upon t h e i n f l u e n c e o f t h e m o d u l a t o r y a r e a s o u t l i n e d i n t h i s i n v e s t i g a t i o n . These s t r u c t u r e s (SC and c o r t e x ) may a l s o f u r t h e r modulate t h e o r i e n t i n g r e s p o n s e by e i t h e r d i r e c t l y i n i t i a t i n g o r i n h i b i t i n g t h e motor systems u n d e r l y i n g subsequent components ( e x p l o r a t i o n & f o l l o w i n g ) i n v o l v e d i n o r i e n t i n g . I t i s t h e s e components o f t h e o r i e n t i n g r e s p o n s e t h a t a r e most a f f e c t e d by SC l e s i o n s . The d i r e c t i o n o f t h e head and l i m b s t o w a r d s a v i s u a l s t i m u l u s i n space r e q u i r e s a c l o s e c o r r e s p o n d e n c e between s e n s o r y and motor p r o c e s s e s i n t h a t t h e motor a p p a r a t u s must be c o n s t a n t l y m o n i t o r e d w i t h r e s p e c t t o p o s i t i o n o f t h e m u s c l e s r e l a t i v e t o a s t i m u l u s . The SC i s i d e a l l y o r g a n i z e d f o r t h i s f u n c t i o n and t h e e l e c t r o p h y s i o l o g i c a l d a t a f r o m r e c o r d i n g and s t i m u l a t i o n e x p e r i m e n t s s u g g e s t i t s i n v o l v e -ment i n d i r e c t e d e x p l o r a t o r y head and eye movements (Wurtz & G o l d b e r g , 1972). The SC i s l i k e l y , however, o n l y i n v o l v e d i n t h e neck and head m o t i o n s as t h e t e c t o - s p i n a l t r a c t o n l y e x t e n d s t o t h e c e r v i c a l l e v e l o f t h e s p i n a l t r a c t (Nyberg & Hansen, 1964) , a n d g r o s s p o s t u r a l 1 15 a d j u s t m e n t s and l i m b c o o r d i n a t i o n and d i r e c t i o n a r e u n a f f e c t e d by SC l e s i o n s (Nyberg & Hansen, 1964; see a l s o Goodale & M u i r i s o n , 1975, and M a r s h a l l , 1978). The SC t h e r e f o r e may be i n v o l v e d i n t h e head and neck movements r e q u i r e d f o r t h e r e f i n e d m u s c l e c o o r d i n a t i o n n e c e s s a r y t o d i r e c t a c t i v i t y t o w a r d s a s t i m u l u s w h i l e o t h e r n e u r a l s t r u c t u r e ( s ) may be i n v o l v e d i n g r o s s p o s t u r a l a d j u s t m e n t s . I t i s i n t h i s sense t h a t t h e n e u r a l s u b s t r a t e s o f o r i e n t i n g b e h a v i o r may p o s s i b l y be d u p l i c a t e d t h r o u g h o u t t h e n e r v o u s system. The r e l a t i o n s h i p o f t h e SC t o t h e a p p r o a c h and f o l l o w i n g components  o f o r i e n t i n g . The r e l a t i o n s h i p between l e s i o n s o f t h e SC and t h e e l i m i n a -t i o n o f f o l l o w i n g , and e x p l o r a t o r y o r a p p r o a c h b e h a v i o r t o w a r d s • s a l i e n t s t i m u l i i s o f i n t e r e s t . T h i s and p r e v i o u s i n v e s t i g a t i o n s ( M a r s h a l l , 1978) have n o t e s t a b l i s h e d whether thc-SC l e s i o n e d a n i m a l s a r e i n c a p a b l e o f t h e s e components o f t h e o r i e n t i n g ' r e s p o n s e o r i f t h e a n i m a l s s i m p l y do n o t emit them i n r e s p o n s e t o v i s u a l s t i m u l i t h a t n o r m a l l y e l i c i t such i n v e s t i g a t o r y b e h a v i o r s by i n t a c t a n i m a l s . S i n c e c e l l s o f t h e SC have c o n n e c t i o n s t o c e l l s c o n t r o l l i n g t h e neck m u s c u l a t u r e , l e s i o n s o f t h e SC, w h i c h d e s t r o y t h e s e c o n n e c t t i o n s , s h o u l d e l i m i n a t e t h e motor r e s p o n s e s . On t h e o t h e r hand, t h e neck m u s c l e s do r e c e i v e p r o j e c t i o n s f r o m o t h e r v i s u a l l y r e s p o n s i v e r e g i o n s v i a c o r t i c a l motor c o n n e c t i o n s . However, t h e s e c o n n e c t i o n s do n o t have t h e d i r e c t 1:1 c o r r e s p o n d e n c e o f t h e SC p r o j e c t i o n s w h i c h may be n e c e s s a r y f o r t h e c o n s t a n t r e f i n e m e n t o f t h e muscle a c t i v i t y i n v o l v e d i n smooth f o l l o w i n g o r p u r s u i t and a p p r o a c h • 1 1 6 movements o f eye and head. The SC l e s i o n e d a n i m a l s were o b s e r v e d t o r e s p o n d w i t h smooth head movements when an a u d i t o r y s t i m u l u s was p r e s e n t e d and engaged i n neck and head movements r e q u i r e d f o r grooming ( E x p e r i m e n t I i ) . As was t h e c a s e f o r t h e d i s r u p t i o n and l o c a l i z a t i o n components o f o r i e n t i n g , i t i s l i k e l y t h a t t h e SC l e s i o n e d a n i m a l s a r e c a p a b l e o f t h e s e responses.,- b u t they, a r e n o t e l i c i t e d by. v i s u a l s t i m u l i t h a t normal a n i m a l s t e n d t o e x p l o r e . These r e l a t i o n s h i p s c o u l d be examined i n s t u d i e s w h i c h r e q u i r e a n i m a l s t o f o l l o w and e x p l o r e v i s u a l s t i m u l i . I m p l i c a t i o n s f o r models o f v i s u a l l y g u i d e d b e h a v i o r . The models o f v i s u a l l y g u i d e d b e h a v i o r r e v i e w e d i n t h e I n t r o d u c t i o n s u g g e s t e d t h a t p a t t e r n v i s i o n i s m e d i a t e d by t h e g e n i c u l o -s t r i a t e s y s t e m w h i l e t h e s u b c o r t i c a l systems were r e s p o n s i b l e f o r s i m p l e r e f l e x i v e b e h a v i o r s . They a l s o s u g g e s t e d t h a t t h e e v a l u a t i o n o f t h e b e h a v i o r a l s i g n i f i c a n c e o f v i s u a l s t i m u l i and t h e t r a n s f o r -m a t i o n o f v i s u a l i n f o r m a t i o n i n t o a d a p t i v e motor b e h a v i o r s were a l s o a f u n c t i o n o f t h e g e n i c u l o - s t r i a t e ' s c o n n e c t i o n s t o t h e l i m b i c system. The f i n d i n g s o f t h i s i n v e s t i g a t i o n o f o r i e n t i n g b e h a v i o r a r e a t odds w i t h t h e s e b r o a d e r models o f v i s u a l l y g u i d e d b e h a v i o r . The s u p e r i o r c o l l i c u l u s was f o u n d t o i n f l u e n c e t h e ease w i t h which o r i e n t i n g b e h a v i o r was e l i c i t e d b y n o v e l s t i m u l i . The s u p e r i o r c o l l i c u l u s a p p e ars t o be i n v o l v e d i n a p r o c e s s by wh i c h t h e b e h a v i o r a l s i g n i f i c a n c e o f a p a r t i c u l a r v i s u a l s t i m u l u s i s a s s e s s e d I 1 7 and t h e n e c e s s i t y o f motor r e s p o n s e s d e t e r m i n e d ( i . e . , whether any o r a l l o f t h e components o f o r i e n t i n g a r e w a r r a n t e d by a p a r t i c u l a r v i s u a l s t i m u l u s ) . F o r example, t h e p r o c e s s e s by w h i c h a v i s u a l s t i m u l u s i s e v a l u a t e d as r e q u i r i n g any o r a l l o f t h e components o f o r i e n t i n g b e h a v i o r i s i n f l u e n c e d by p a r a m e t e r s i n t r i n s i c t o t h e o r g a n i s m , and-by t h e m o t i o n , i n t e n s i t y , and p a t t e r n o f a v i s u a l s t i m u -l u s . I n p a r t i c u l a r , t h i s i n v e s t i g a t i o n f o u n d t h a t t h e p a t t e r n o f a s t i m u l u s ( E x p e r i m e n t I V ) i s an i m p o r t a n t d e t e r m i n a n t o f o r i e n t i n g . F o r t h i s r e a s o n i t may be c o u n t e r p r o d u c t i v e t o s e p a r a t e t h e n e u r a l s u b s t r a t e s o f v i s u a l l y g u i d e d b e h a v i o r i n t o one s y s t e m f o r p a t t e r n v i s i o n and a n o t h e r s y s t e m f o r o r i e n t i n g b e h a v i o r . The r e l a t i o n s h i p between t h e n e u r a l s u b s t r a t e s o f v i s u a l l y g u i d e d b e h a v i o r a r e f a r more complex t h a n t h o s e i m p l i c i t i n t h e b r o a d e r models. F i g u r e 24 summarizes t h e l e s i o n - b e h a v i o r r e s u l t s o f t h i s i n v e s t i g a t i o n and some of- the- c o n n e c t i o n s w h i c h must be c o n s i d e r e d i n any adequate a c c o u n t o f o r i e n t i n g b e h a v i o r and, q u i t e p o s s i b l y , o t h e r a s p e c t s o f v i s u a l l y g u i d e d b e h a v i o r . J I 8 Note 1. A v e r s i o n o f t h i s argument' c o u l d a l s o be a p p l i e d t o t h e p r e s e n t i n v e s t i g a t i o n . I f measures o f autonomic n e r v o u s s y s t e m changes, r e s p i r a t o r y changes o r s m a l l eye movements had been r e c o r d e d , e v i d e n c e o f o r i e n t a t i o n t o even t h e l e s s s a l i e n t v i s u a l d i s p l a y s and d i s h a b i t u a t i o n t o t h e changes i n t h e l i g h t d i s p l a y s b y l e s i o n e d a n i m a l s might have been o b t a i n e d . [ S i n c e n o r m a l r a t s do n o t s h i f t t h e p o s i t i o n o f t h e eyes i n d e p e n d e n t l y o f changes i n head and body p o s i t i o n ( D r a g e r & H u b e l , 1975) eye movements a r e n o t l i k e l y t o have o c c u r r e d i n d e p e n d e n t o f head and p o s t u r a l a d j u s t m e n t s w h i c h w o u l d l i k e l y have been i n c o m p a t i b l e w i t h l i c k i n g t h e w a t e r s p o u t .J I f f u r t h e r r e s e a r c h d e m o n s t r a t e d t h a t autonomic o r o t h e r p h y s i o -l o g i c a l changes do o c c u r i n r e s p o n s e t o v i s u a l s t i m u l i i t would r e i n f o r c e t h e g e n e r a l c o n c l u s i o n o f t h i s r e p o r t t h a t o r i e n t i n g i s n o t e n t i r e l y e l i m i n a t e d by SG l e s i o n s . 119. REFERENCES An d e r s o n , K. V., & W i l l i a m s o n , M. R. V i s u a l p a t t e r n d i s c r i m i n a t i o n i n c a t s a f t e r r e m o v a l o f t h e s u p e r i o r c o l l i c u l u s . Psychonomic  S c i e n c e , 1971, 24, 124-127. A n d e r s o n , K. V., & Symmes, D. The s u p e r i o r c o l l i c u l u s and h i g h e r v i s u a l f u n c t i o n s i n t h e monkey. B r a i n R e s e a r c h , 1969, 13? 37-52. B a r l o w , H. B., Narasimhan, R., & R o s i n f e l d , A. V i s u a l p a t t e r n a n a l y s i s i n machines and a n i m a l s . S c i e n c e , 1972, 177, 5&7~575• B a r n e s , P. J . , S m i t h , L. M., & L a t t o , R. M. O r i e n t a t i o n t o v i s u a l s t i m u l i and t h e s u p e r i o r c o l l i c u l u s i n t h e r a t . Q u a r t e r l y  J o u r n a l o f E x p e r i m e n t a l P s y c h o l o g y , 1970, 22, 239-247. B e r l u c c h i , G., Spragu e , J . M., Levey, J . , & D i B e r a r d i n o , A. C. The p r e t e c t u m and s u p e r i o r c o l l i c u l u s i n v i s u a l l y g u i d e d b e h a v i o r and i n f l u x and f o r m d i s c r i m i n a t i o n i n t h e c a t . J o u r n a l o f  Com p a r a t i v e and P h y s i o l o g i c a l P s y c h o l o g y (monograph), 1972, 78, 123-172. B l o c h e r t , P. K., F e r r i e r , R. J . , & Cooper, R. M. E f f e c t o f p r e -t e c t a l l e s i o n s on r a t s w e a r i n g l i g h t d i f f u s i n g o c c l u d e r s . B r a i n R e s e a r c h , 1976, 104, 121-128. C a s a g r a n d e , V. A., & Diamond, I . T. A b l a t i o n s t u d y o f t h e s u p e r i o r c o l l i c u l u s i n t h e t r e e shrew ( T u p a i a g l i s ) . J o u r n a l o f Compara-t i v e N e u r o l o g y , 1974, 156, 207-238. C a s t i g l i o n i , A. J . , G a l l o w a y , M. C., & C o u l t e r , J . D. S p i n a l p r o j e c -t i o n s f r o m t h e m i d b r a i n i n monkey. J o u r n a l o f Co m p a r a t i v e  N e u r o l o g y , 1978, 172, 329-337-C h a l u p a , L. M. A r e v i e w o f c a t and monkey s t u d i e s i m p l i c a t i n g t h e p u l v i n a r i n v i s u a l f u n c t i o n . B e h a v i o r a l B i o l o g y , 1977, 20, 149-167. Cooper, R. M., B l o c h e r t , K. P., G i l l e s p i e , L. A., & M i l l e r , L. G. T r a n s l u c e n t o c c l u d e r s and l e s i o n s o f p o s t e r i o r n e o c o r t e x i n r a t . P h y s i o l o g y and B e h a v i o r , 1972, 8, 693-697. Cooper, R. M., B l a n d , B. H., G i l l e s p i e , L. A., & W h i t a k e r , R. H. U n i l a t e r a l p o s t e r i o r c o r t i c a l and u n i l a t e r a l c o l l i c u l a r ... l e s i o n s and. v i s u a l l y . g u i d e d b e h a v i o r , im-the- rat.. • J o u r n a l o f Comparative and P h y s i o l o g i c a l P s y c h o l o g y , 1970, 72, 286-295-Gynader, M., & Berman, N. R e c e p t i v e - f i e l d o r g a n i z a t i o n o f monkey s u p e r -i o r c o l l i c u l u s . J o u r n a l o f N e u r o p h y s i o l o g y , 1972, 35_, 187-201. 120 Denny-Brown, D. The m i d b r a i n and motor i n t e g r a t i o n . P r o c e e d i n g s o f  th e R o y a l S o c i e t y o f M e d i c i n e , 1962, 5_5_, 527-538. Diamond, I . T. O r g a n i z a t i o n o f t h e v i s u a l c o r t e x : C o m p a r a t i v e ana-t o m i c a l a n d " b e h a v i o r a l s t u d i e s . F e d e r a t i o n P r o c e e d i n g s , 1976, 25_, 60-67. Doty, R. W. S u r v i v a l o f p a t t e r n v i s i o n a f t e r r e m o v a l o f s t r i a t e c o r -t e x i n t h e a d u l t c a t . J o u r n a l o f Co m p a r a t i v e N e u r o l o g y , 1971, 143, 341-370. Dow, B. M., & Gouras, P. C o l o r and s p a t i a l s p e c i f i c i t y o f s i n g l e u n i t s i n r h e s u s monkey f o v e a l s t r i a t e c o r t e x . J o u r n a l o f Neuro-p h y s i o l o g y , 1973, 36, 79-101. D r a g e r , U. C , & H u b e l , D. H. Response t o v i s u a l s t i m u l a t i o n and r e l a t i o n s h i p between v i s u a l , a u d i t o r y , and s o m e s t h e t i c i n p u t s i n mouse s u p e r i o r c o l l i c u l u s . J o u r n a l o f N e u r o p h y s i o l o g y , 1975, 38, 690-713. D r a g e r , U., & H u b e l , D. Topography o f v i s u a l and so m a t o s e n s o r y p r o -j e c t i o n s t o mouse s u p e r i o r c o l l i c u l u s . J o u r n a l o f N e u r o p h y s i - o l o g y , 1976, 39, 91-101. Dyer, R. S., M a r i n o , M. F., Jo h n s o n , C , & K r u g g e l , T. S u p e r i o r c o l l i c u l u s l e s i o n s do n o t i m p a i r o r i e n t a t i o n t o p a t t e r n . B r a i n  R e s e a r c h , 1976, 112, 176-179-Edwards, S. B., & H e n k e l , C. K. S u p e r i o r c o l l i c u l u s c o n n e c t i o n s w i t h t h e e x t r a c o l l i c u l a r motor n u c l e i i n t h e c a t . J o u r n a l o f Compar-a t i v e N e u r o l o g y , 1978, 179, 451-468. F e r r i e r , R. J . , & Cooper R. M. S t r i a t e . c o r t e x - a b l a t i o n s 'and s p a t i a l v i s i o n . B r a i n R e s e a r c h , 1976, -106, 71-85. F i l e , S.. E. E f f e c t s o f s t i m u l u s "duration'-.'-arid i n t e n s i t y , on t h e r a t e o f b e h a v i o r a l h a b i t u a t i o n . Q u a r t e r l y J o u r n a l o f E x p e r i m e n t a l  P s y c h o l o g y , 1973, 25., 96-103. G o o d a l e , M. A. C o r t i c o - t e c t a l and i n t e r t e c t a l . . modulation-.of' v i s u a l r e s p o n s e s i n t h e r a t s ' s u p e r i o r c o l l i c u l u s . E x p e r i m e n t a l B r a i n  R e s e a r c h , 1973, 19, 75-86. Goodale, M. A., & M u i r i s o n , R. C. The e f f e c t s o f l e s i o n s o f t h e s u p e r i o r c o l l i c u l u s on l o c o m o t o r o r i e n t a t i o n and t h e o r i e n t i n g r e f l e x i n t h e r a t . B r a i n R e s e a r c h , 1975, 88, 243-261. G o o d a l e , M.A., & L i s t e r , T.M. A t t e n t i o n t o n o v e l s t i m u l i i n r a t s w i t h l e s i o n s o f t h e s u p e r i o r c o l l i c u l u s . B r a i n R e s e a r c h , 1974, 66, 361-362. 121. G o o d a l e , M. A., Foreman, N., & M i n e r , A.D. V i s u a l , o r i e n t a t i o n i n t h e r a t : a. d i s s o c i a t i o n o f d e f i c i t s f o l l o w i n g c o r t i c a l and c o l l i c u -l e s i o n s . E x p e r i m e n t a l B r a i n R e s e a r c h , 1977• G o o d a l e , M. A., M i n e r , A. D., & Rose,. J . S u s c e p t i b i l i t y t o s t a r t l e d u r i n g o n g o i n g b e h a v i o r f o l l o w i n g c o l l i c u l a r l e s i o n s i n t h e r a t . N e u r o s c i e n c e L e t t e r s , 1975, 1 333-337-Gordon, B. R e c e p t i v e f i e l d s i n deep l a y e r s o f c a t s u p e r i o r c o l l i c u -l u s . J o u r n a l o f N e u r o p h y s i o l o g y , 1973, 3.6, 157-178. G r a y b i e l , A. M. S t u d i e s on t h e a n a t o m i c a l o r g a n i z a t i o n o f p o s t e r i o r a s s o c i a t i o n c o r t e x . I n F. 0. S c h m i t t & F. G. Worden ( E d s . ) , The N e u r o s c i e n c e s : T h i r d S t u d y Program, 1974, M T p r e s s , Gam-b r i d g e , M a s s a c h u s e t t s , 105-214. G o u l d , H. J . , I l l , H a l l , W. G., & Ebn e r , F. F. C o n n e c t i o n s o f t h e v i s u a l c o r t e x i n t h e hedgehog ( P a r a e c h i n u s h y p o m e l a s ) . I . Th a l a m i c p r o j e c t i o n s . J o u r n a l o f Comparative N e u r o l o g y , 1978, 177, 445-472. G o u l d , H. J . , & Ebner, F. F. I n t e r l a m i n a r c o n n e c t i o n s o f t h e v i s u a l c o r t e x i n t h e hedgehog ( P a r a e c h i n u s h y p o m e l a s ) . J o u r n a l o f  C o m p a r a t i v e N e u r o l o g y , 1978, 177, 503-518. Hayhow, W. R., S e f t o n , A., & Webb, C. P r i m a r y o p t i c c e n t e r s o f t h e . r a t i n r e l a t i o n t o t h e t e r m i n a l d i s t r i b u t i o n o f t h e c r o s s e d and u n c r o s s e d o p t i c n e r v e f i b e r s . J o u r n a l o f C o m p a r a t i v e N e u r o l o g y , 1962, .118, 295-322. Hayhow, W. R., Webb, C , & J e r v i e , A. An e x p e r i m e n t a l s t u d y o f t h e a c c e s s o r y o p t i c f i b e r s y s t e m i n t h e r a t . J o u r n a l o f C o m p a r a t i v e  N e u r o l o g y , i960, 115_f 187-215-H o r e l , J . i A . E f f e c t s o f s u b c o r t i c a l l e s i o n s on b r i g h t n e s s d i s c r i m -i n a t i o n s a c q u i r e d by r a t s w i t h o u t v i s u a l c o r t e x . J o u r n a l o f  Com p a r a t i v e and P h y s i o l o g i c a l P s y c h o l o g y , 1968, 65_, 103-109. H o r e l , J . A., K e a t i n g , G., & M s a n t o n e , L. J . P a r t i a l K l u v e r - B u c y syndrome p r o d u c e d b y d e s t r o y i n g t e m p o r a l n e o c o r t e x o r amygdala. B r a i n R e s e a r c h , 1975, 94, 347-359-H u b e l , D. H., & W i e s e l , T. N. R e c e p t i v e f i e l d s , . . b i n o c u l a r " i n t e r a c -t i o n and f u n c t i o n a l a r c h i t e c t u r e i n t h e c a t ' s v i s u a l c o r t e x . J o u r n a l o f N e u r o p h y s i o l o g y , 1962, l60, 106-154. H u b e l , D. H.M & W i e s e l , T. N. R e c e p t i v e f i e l d s and f u n c t i o n a l a r c h i -t e c t u r e i n two n o n - s t r i a t e a r e a s (18-19) o f t h e c a t . J o u r n a l  o f N e u r o p h y s i o l o g y , 1965, 28, 229-289. 1 22 H u b e l , D. H., & W i e s e l , T. N. R e c e p t i v e f i e l d s and f u n c t i o n a l a r c h i -t e c t u r e o f monkey s t r i a t e c o r t e x . J o u r n a l o f P h y s i o l o g y , 1968, 195, 215-243. H u b e l , D. H., & W i e s e l , T. N. F u n c t i o n a l a r c h i t e c t u r e o f macaque monkey v i s u a l c o r t e x . ^ P r o c e e d i n g s o f the R o y a l S o c i e t y o f London. B, 1977, 198 , 1-59-Hughes, H. G. A n a t o m i c a l and n e u r o b e h a v i o r a l i n v e s t i g a t i o n s c o n - " - -" c e r n i n g t h e t h a l a m o - c o r t i c a l o r g a n i z a t i o n o f t h e r a t ' s v i s u a l s y s t e m . The J o u r n a l o f Co m p a r a t i v e N e u r o l o g y , 1977, 175» 311-336. I n g l e , D. J.".. The f r o g ' s v i s u a l s y s t e m asaa'model f o r - t h e "study o f s e l e c t i v e a t t e n t i o n . I n D. J . I n g l e & H. M. S h e i n ( E d s ) , ModelsSysterns i n B i o l o g i c a l P s y c h i a t r y , 1975> Cambridge, Mass. MET p r e s s , 113-131. I n g l e , D. E v o l u t i o n a r y p e r s p e c t i v e s on t h e f u n c t i o n o f t h e o p t i c t e c t u m . B r a i n B e h a v i o r and E v o l u t i o n , 1973, 8, 211-237. I n g l e , D., & Spragu e , J . M. S e n s o r i m o t o r f u n c t i o n o f t h e m i d b r a i n t e c t u m . N e u r o s c i e n c e s R e s e a r c h B u l l e t i n , 1975. 12.> 169-288. Jane, J . A., Levey , N., & C a r l s o n , N. J . T e c t a l and c o r t i c a l f u n c -t i o n i n v i s i o n . E x p e r i m e n t a l N e u r o l o g y , 1972, 35» 61-77• J o n e s , E. G. TThe anatomy o f e x t r a g e n i c u l a t e v i s u a l mechanisms. I n F. 0. S c h m i t t &::.F. G. Worden ( E d s . ) , The N e u r o s c i e n c e s T h i r d  S t u d y Program, .1974, MIT press.j Cambridge, Mass215-227. J o n e s , B., & M i s h k i n , M. L i m b i c l e s i o n s and t h e p r o b l e m o f s t i m u l u s -r e i n f o r c e m e n t a s s o c i a t i o n s . E x p e r i m e n t a l N e u r o l o g y , 1972, 36, .362-377. K i l l a c k e y , H., Snyder, M., & Diamond, I . T. F u n c t i o n o f s t r i a t e and "temporal c o r t e x i n t h e t r e e shrew. J o u r n a l o f Co m p a r a t i v e  and P h y s i o l o g i c a l P s y c h o l o g y (monograph), 1971, 74, 1-29. K i r v e l , R. D., G r e e n f i e l d , R. A., & Meyer, D. R. M u l t i m o d a l s e n s o r y n e g l e c t i n r a t s w i t h r a d i c a l u n i l a t e r a l p o s t e r i o r i s o c o r t i c a l and s u p e r i o r c o l l i c u l a r a b l a t i o n s . J o u r n a l o f Comp a r a t i v e and  P h y s i o l o g i c a l P s y c h o l o g y . 1974, 87,' I56-I62. K i r k , R. E. E x p e r i m e n t a l D e s i g n : P r o c e d u r e s f o r t h e B e h a v i o r a l S c i e n c e s . B e l m o n t , C a l i f o r n i a : B r o o k s / Cole,19687 123 K l u v e r , H., & Bucy, P. G. P r e l i m i n a r y a n a l y s i s o f f u n c t i o n s o f t h e t e m p o r a l l o b e s i n monkeys. A r c h i v e s o f N e u r o l o g y , 1939, 4 2 , 979-1000. K l u v e r , H. V i s u a l f u n c t i o n s a f t e r r e m o v a l o f t h e o c c i p i t a l l o b e s . J o u r n a l o f P s y c h o l o g y , 1941, 11, 23-45. K l u v e r , H. F u c n c t i o n a l s i g n i f i c a n c e o f t h e g e n i c u l o - s t r i a t e s y s t e m . B i o l o g i c a l Symposia, 1942, ?:, 263-299. K l u v e r , H. F u n c t i o n a l d i f f e r e n c e s between t h e o c c i p i t a l and t e m p o r a l l o b e s . I n J e f f r e s s , 1. A ( E d . ) , C e r e b r a l Mechanisms i n B e h a v i o r , New York: W i l e y , 1951, 147-182. K r i e g , W. J . S. C o n n e c t i o n s o f t h e c e r e b r a l c o r t e x . I . The a l b i n o r a t . A. Topography o f t h e c o r t i c a l a r e a s . The J o u r n a l o f  Compa r a t i v e N e u r o l o g y , 1946a, 8 4 , 221-276. K r i e g , W. J . S. C o n n e c t i o n s o f t h e c e r e b r a l c o r t e x . I I . The a l b i n o r a t . B. S t r u c t u r e o f t h e c o r t i c a l a r e a s . The J o u r n a l  o f C o m p a r a t i v e N e u r o l o g y , 1946b, 8 4 , 277 -284 . K o n i g , J . F. R., & K l i p p e l , R. A. The Ra t B r a i n . B a l t i m o r e : W i l l i a m s & W i l k i n s , I963. L e g g , C. R., & Cowey, A. The r o l e o f t h e v e n t r a l l a t e r a l g e n i c u l a t e n u c l e u s and p o s t e r i o r thalamus i n i n t e n s i t y d i s c r i m i n a t i o n i n r a t s . B r a i n R e s e a r c h , 1977, 123_, 261-273-L e v e y , N. H., & Ja n e , J . A. Lami n a r t h e r m o c o a g u l a t i o n o f t h e v i s u a l c o r t e x i n t h e r a t . I I . V i s u a l p a t t e r n d i s c r i m i n a t i o n . B r a i n , B e h a v i o r and E v o l u t i o n , 1975, 111 275-321. Lund, R. D. The o c c l p i t o t e c t a l pathway i n t h e r a t . J o u r n a l o f  Anatomy, 1966, 100, 51-62. L y n n , R. A t t e n t i o n , A r o u s a l and t h e O r i e n t a t i o n R e a c t i o n . New York: Permagon P r e s s , I966. M a c k i n t o s h , N. J . S t i m u l u s c o n t r o l : a t t e n t i o n a l f a c t o r s . I n : W. K. H o n i g & J . E. R. Sta d d o n ( E d s . ) , Handbook o f Operant  B e h a v i o r . Englewood C l i f f s : P r e n t i c e - H a l l I n c . , 1977-Maekawa, K., & Takeda, T. E l e c t r o p h y s i o l o g i c a l i d e n t i f i c a t i o n o f th e c l i m b i n g and mossy f i b e r pathways f r o m t h e r a b b i t ' s r e t i n a t o t h e c o n t r a l a t e r a l c e r e b e l l a r f l o c c u l u s . B r a i n R e s e a r c h , 1976, 109, 169-174. 1 2 4 . M a r s h a l l , J . F. Comparison o f t h e s e n s o r i m o t o r d y s f u n c t i o n s p r o d u c e d by damage t o l a t e r a l hypothalamus o r s u p e r i o r c o l l i c u l u s i n t h e r a t . E x p e r i m e n t a l N e u r o l o g y , 1978, 5.8, 203-217-Marx, J i L. O p i a t e r e c e p t o r s : I m p l i c a t i o n s and a p p l i c a t i o n s . S c i e n c e , 1975, 1 8 9 , 708-710. M i l l e r , L. G. T r a n s l u c e n t o c c l u d e r s and t h e r o l e o f v i s u a l c o r t e x i n p a t t e r n v i s i o n . U n p u b l i s h e d M a s t e r ' s T h e s i s , U n i v e r s i t y o f C a l g a r y , 1973-M i l l e r , L. G., & Cooper, R. M... T r a n s l u c e n t . o c c l u d e r s .and t h e r o l e o f t h e v i s u a l c o r t e x i n p a t t e r n v i s i o n . B r a i n R e s e a r c h , 1974, 79, 45-59-M i l n e r , P. M. A model f o r v i s u a l shape r e c o g n i t i o n . P s y c h o l o g i c a l  Review, 1974, 8 1 , 521-535-Myers, R. E. V i s u a l d e f i c i t s a f t e r l e s i o n s o f b r a i n stem tegmentum i n c a t s . A r c h i v e s o f N e u r o l o g y , 1 9 6 4 , _11, 73~90. Nyberg-Hansen, R. The l o c a t i o n and t e r m i n a t i o n o f t e c t o - s p i n a l i n the' c a t . E x p e r i m e n t a l N e u r o l o g y , 1 9 6 4 , 9, 212-227-Page, C. H., & S u t t e r l i n , A. M. V i s u a l - a u d i t o r y u n i t r e s p o n s e i n t h e g o l d f i s h tegmentum. J o u r n a l o f N e u r o p h y s i o l o g y , 1970, 33, 129-136. P i n e l , J . P. J . , & Van Oot, P. H. I n t e n s i f i c a t i o n o f t h e a l c o h o l w i t h d r a w a l syndrome f o l l o w i n g p e r i o d i c e l e c t r o c o n v u l s i v e s h o c k s . B i o l o g i c a l P s y c h i a t r y , 1977, 12, 479 - 4 8 6 . R i b a k , C. E., & P e t e r s , A. An a u t o r a d i o g r a p h i c s t u d y o f t h e p r o j e c -t i o n s f r o m t h e l a t e r a l g e n i c u l a t e body o f r a t . B r a i n R e s e a r c h , 1975, 92, 341-368. R o l l s , E. T., Judge, S. J . , & Sanghera, M. K . A c t i v i t y o f neurones i n t h e i n f e r o t e m p o r a l c o r t e x o f t h e a l e r t monkey. B r a i n  R e s e a r c h , 1977, 13_0, 229-238. S c h a e f e r , K . P. U n i t a n a l y s i s and e l e c t r i c a l s t i m u l u a t i o n i n t h e o p t i c t e c t u m o f r a b b i t s and c a t s . B r a i n , B e h a v i o r and E v o l u t i o n , 1970, 3, 2 2 2 - 2 4 0 . 125. S c h i l d e r , P., P a s i k , P., & P a s i k , T. E x t r a g e n i c u l o - s t r i a t e v i s i o n i n t h e monkey. I I I . C i r c l e v s . t r i a n g l e and " r e d v s . g r r e n " d i s c r i m i n a t i o n . E x p e r i m e n t a l B r a i n R e s e a r c h , 1972, .14, 436-448. S c h i l l e r , P. H., & S t r y k e r , M. S i n g l e u n i t r e c o r d i n g and s t i m u l a t i o n i n s u p e r i o r c o l l i c u l u s o f t h e a l e r t r h e s u s monkey. J o u r n a l o f N e u r o p h y s i o l o g y , 1972, 35_, 915-924. S c h n e i d e r , G. E. C o n t r a s t i n g v i s u o m o t o r f u n c t i o n s o f t e c t u m and c o r t e x i n t h e g o l d e n hamster. P s y c h o l o g i s c h e F o r c h u n g , 1967, 31, 52-62. S c h n e i d e r , G. E. Two v i s u a l s y s t e m s . S c i e n c e , 1969, 163, 895-902. S c h n e i d e r , G. E. Two v i s u o m o t o r systems i n t h e S y r i a n h a m s t e r . I n D. I n g l e & J . M. Sprague ( E d s . ) , S e n s o r i m o t o r F u n c t i o n o f t h e  M i d b r a i n Tectum. N e u r o s c i e n c e s R e s e a r c h B u l l e t i n , 1975, 13, 255-257-Sherman, S. M. V i s u a l f i e l d s o f c a t s w i t h c o r t i c a l and t e c t a l l e s i o n s . S c i e n c e , 1974, 185, 355"357-Sherman, S. M. The e f f e c t o f s u p e r i o r c o l l i c u l u s l e s i o n s upon t h e v i s u a l f i e l d s o f c a t s -with c o r t i c a l a b l a t i o n s . J o u r n a l o f Co m p a r a t i v e N e u r o l o g y , 1977, 172, 211-230. S m i t h , C. J . , & Weldon, D. A. H y p e r a c t i v i t y and d e f i c i t s i n p r o b l e m s o l v i n g f o l l o w i n g s u p e r i o r c o l l i c u l u s l e s i o n s i n t h e r a t . P h y s i o l o g y and B e h a v i o r , 1976, 16, 381-385-S m i t h , K. U. V i s u a l d i s c r i m i n a t i o n i n t h e c a t : V. The p o s t o p e r a -t i v e e f f e c t s o f r e m o v a l o f t h e s t r i a t e c o r t e x upon i n t e n s i t y d i s c r i m i n a t i o n . J o u r n a l o f G e n e t i c P s y c h o l o g y , 1937(b), 51, 329-369. S n y d e r , M., & Diamond, I.. T. The o r g a n i z a t i o n and f u n c t i o n o f t h e v i s u a l c o r t e x i n t h e t r e e shrew. B r a i n , B e h a v i o r and E v o l u t i o n , 1968, 1, 244-288. Sprague, J . M. I n t e r a c t i o n o f c o r t e x and s u p e r i o r c o l l i c u l u s i n m e d i a t i o n o f v i s u a l l y g u i d e d b e h a v i o r . S c i e n c e , 1966, 153, 1544-1547. Sprague, J . M. Mammalian t e c t u m : I n t r i n s i c o r g a n i z a t i o n , a f f e r e n t i n p u t s , and i n t e g r a t i v e mechanisms. A n a t o m i c a l s u b s t r a t e s . I n D. I n g l e & J.-'M.. Sprague ( E d s . ) , S e n s o r i m o t o r F u n c t i o n - of' t h e  M i d b r a i n ' Tectum. N e u r o s c i e n c e s R e s e a r c h Program B u l l e t i n , 1975 12, 204-213. .126 S p r a g u e , J . M., & M e i k l e , T. H. The r o l e o f t h e s u p e r i o r c o l l i c u l u s i n v i s u a l l y g u i d e d b e h a v i o r . E x p e r i m e n t a l N e u r o l o g y , 1 9 6 5 , 1 1 , 115-146. S p r a g u e , J . M., B e r l u c c h i , G., & D i B e r a r d i n o , A. The s u p e r i o r c o l -l i c u l u s and p r e t e c t u m i n v i s u a l l y g u i d e d b e h a v i o r and v i s u a l d i s c r i m i n a t i o n i n t h e c a t . B r a i n , B e h a v i o r and E v o l u t i o n , 1970 , J , 285-294. S p r a g u e , J . M., Levey , J . , D i B e r a r d i n o , A., & B e r l u c c h i , G. V i s u a l c o r t i c a l a r e a s m e d i a t i n g f o r m d i s c r i m i n a t i o n i n t h e c a t . J o u r n a l o f Com p a r a t i v e N e u r o l o g y , 1977 , 1 2 2 , 4 4 1 - 4 8 8 . T e e s , R. C. The e f f e c t s o f n e o n a t a l s t r i a t e l e s i o n s a n d ' v i s u a l e x p e r i -ence on f o r m d i s c r i m i n a t i o n i n t h e r a t . C a n a d i a n J o u r n a l o f  P s y c h o l o g y , 1975 , 29 ,\-66-85. Tees, R. C. E f f e c t o f e a r l y r e s t r i c t i o n on l a t e r f o r m d i s c r i m i n a t i o n i n t h e r a t . C a n a d i a n J o r n a l o f P s y c h o l o g y , 1968 , 2 2 , 2 9 4 - 2 9 8 . Thompson, R. L o c a l i z a t i o n o f t h e " v i s u a l memory^system" i n t h e w h i t e r a t . J o u r n a l o f C o m p a r a t i v e and P h y s i o l o g i c a l P s y c h o l o g y , (monograph supplement),. 1969, 69, ( 4 , P a r t 2 ) , 1-29. T r y g g v a s o n , S., & Tees, R. C. R e t e n t i o n o f t h r e e b r i g h t n e s s d i s c r i m -i n a t i o n s b y r a t s f o l l o w i n g p o s t e r i o r c o r t i c a l l e s i o n s . J o u r n a l  o f C o m p a r a t i v e and P h y s i o l o g i c a l P s y c h o l o g y , 1974 , 8 6 , 637-647-V a l l e , F. P., & B o l s , R. J . Age f a c t o r s i n s e x d i f f e r e n c e s i n open-f i e l d a c t i v i t y o f r a t s . A n i m a l L e a r n i n g and B e h a v i o r , 1976 , 4 , 4 5 7 - 4 6 0 . W e l s k r a n t z , L. The i n t e r a c t i o n between o c c i p i t a l and t e m p o r a l c o r t e x i n v i s i o n : An o v e r v i e w . I n F . - , 0 . S c h m i t t & F. G. Worden ( E d s . ) The N e u r o s c i e n c e s T h i r d S t u d y Program, 1974 , 1 8 9 - 2 0 4 , Cambridge, M a s s a c h u s e t t s , MIT P r e s s . W i c k e l g r e n , B., & S t e r l i n g , P. I n f l u e n c e o f v i s u a l c o r t e x on r e c e p -t i v e , f i e l d s i n t h e s u p e r i o r c o l l i c u l u s . o f - t h e c a t . J o u r n a l o f  N e u r o p h y s i o l o g y , I969, 3.2, 16-23. W i l k i e , D. M., & Masson, M. E. A t t e n t i o n i n t h e p i g e o n : a r e - e v a l -u a t i o n . J o u r n a l o f t h e " E x p e r i m e n t a l . A n a - l y s i s o f " B e h a v i o r , 1 9 7 6 , 26, 2 0 7 - 2 1 2 . Wing, K. G., & S m i t h , K. U. The r o l e o f t h e o p t i c c o r t e x i n t h e dog i n t h e d e t e r m i n a t i o n o f t h e f u n c t i o n a l p r o p e r t i e s o f c o n d i t i o n e d r e a c t i o n s t o l i g h t . J o u r n a l o f E x p e r i m e n t a l P s y c h o l o g y , 1942 , 31, 478-496. 127. W i n t e r k o r n , J . M. S. S i m i l a r d e f i c i t s i n v i s u a l l e a r n i n g b y c a t s w i t h l e s i o n s o f t h e f r o n t a l c o r t e x o r o f t h e s u p e r i o r c o l l i c u l u s . B r a i n R e s e a r c h , 1975, 83, I63-I68. W u r t z , R. H., & M o h l e r , G. ¥. O r g a n i z a t i o n o f monkey s u p e r i o r c o l -l i c u l u s : ''enhanced v i s u a l r e s p o n s e o f s u p e r f i c i a l l a y e r s . J o u r n a l o f N e u r o p h y s i o l o g y , 1976, 22, 7^5-%5. W u r t z , R. H., & G o l d b e r g , M. E. A c t i v i t y o f s u p e r i o r c o l l i c u l u s i n b e h a v i n g monkey. .IV. E f f e c t s o f l e s i o n s on eye movements. J o u r n a l o f N e u r o p h y s i o l o g y , 1972, 35-j 587-596. APPENDIX A A n a l y s i s o f V a r i a n c e F T a b l e s . 129 T a b l e 1 A n a l y s i s o f V a r i a n c e F T a b l e T r i a l s ,1-5 f o r SI,. S2, "S3 and,S4, E x p e r i m e n t I C o n v e n t i o n a l F t e s t G e i s s e r Greenhouse C o n s e r v a t i v e F t e s t Degrees o f Mean Source Freedom Square F P r o b . F Exceed e d Degrees o f P r o b . F Freedom E x c e e d e d Mean 1 1264473.00000 1293.43115 '0.000 G 4 2395 -84668 2.45071 • 0.064 E r r o r 35 977-61133 P 3 513.20825 3.75069 0.013 1, 35 P .05 PG 1 2 24.0.09863 1 . 7 5 0 0 4 0.066 4, 35 P .10 E r r o r 105 137 . 1 9 6 0 4 T 4 174.54883 2.23588 : 0.068 1, 35 P .10 TG 16 142.59644 1.82659 0.033 4, 35 P .10 E r r o r 1 4 0 78.06718 PT 12 110.97266 1 . 8 6 8 2 8 0.036 1, 35 P .10 PT.G 4 8 53-775^ 0.90534 0.655 4, 35 P .25 E r r o r 4 2 0 59-39815 S 1 7351.92578 61.78020 • 0.000 1, 35 P .00 SG 4 1351.13477 11.35395 0.000 4 , 35 P .00 • E r r o r 35 119.00133 PS 3 397-92822 8 . 6 8 0 4 8 0.000 1, 35 P .01 PSG 12 106.96094 2.33327 0.011 4, 35 P .10 E r r o r 105 4 5 . 8 4 1 7 4 TS 4 425.78320 7 . 4 8 8 8 6 0.000 1, 35 P .05 TSG 16 110 . 1 4 8 6 8 1 . 9 3 7 3 4 - 0.022 4, 35 P .10 E r r o r 1 4 0 56.85551 PTS 12 64.77994 I.54063 0.106 1, 35 • P .10 PTSG 4 8 51.60318 1.22726 - 0.151 4, 35 P .25 E r r o r 4 2 0 42.04758 N o t e . G = L e s i o n group. P = S t i m u l u s p a t t e r n . T = T r i a l . S = S t i m u l u s v e r s u s b a s e l i n e . 130 T a b l e 2 A n a l y s i s o f V a r i a n c e F T a b l e T r i a l s 1-30 f o r S I and S2, E x p e r i m e n t I G e i s s e r Greenhouse C o n v e n t i o n a l F t e s t C o n s e r v a t i v e F t e s t Degrees y o f Mean Prob.. F Degrees o f P r o b . F S o u r c e Freedom 1 Square F Exceeded Freedom Exceeded Mean 1 2025994.00000 1939.40527 - 0.000 G 4 I836.71875 1.75822 = 0.159 E r r o r 35 1044.64697 P 1 0.0 0.0 • 1.000 PG 4 119.35590 1.05761 • 0.392 E r r o r 35 112.85408 T 14 322.70776 5.63135 0.000 1, 35 •P- < .05 TG 56 100.56284 1.75485 0.001 4, 35 P > .10 E r r o r 490 57.30560 PT 14 77.24748 I.25898 0.229 1. 35 P > .25 PTG 56 67.41168 1.09868 0.298 4, 35 P > .25 E r r o r 490 61.35704 S 1 1886.95508 20.56580 0.000 SG 4 345.95166 3.7705.O 0.012 E r r o r 35 91.75206 PS 1 148.09595' 3.78170 0.060 PSG 4 73.48230 1.87641 0.136 E r r o r 35 39.16119 TS 14 439.91357 11.14905 = 0.0 1, 35 p < .01 TSG 56 90.50703 2.29379 • 0.000 4, 35 p >.05 E r r o r 490 39.45749 PTS 14 65.61133 1.71820 • 0.049 1, 35 p >..10 PTSG 56 49.94370 1.30790 - 0.074 4, 35 P > -25 E r r o r 490 38.18611 N o t e . G = ' l e s i o n group. P = S t i m u l u s p a t t e r n . T -= . T r i a l . S = S t i m u l u s v e r s u s b a s e l i n e . 131 T a b l e 3 A n a l y s i s o f V a r i a n c e F T a b l e f o r E x p e r i m e n t I I G e i s s e r Greenhouse C o n v e n t i o n a l F t e s t C o n s e r v a t i v e F t e s t S o u r c e Degrees o f Freedom Mean Square F P r o b . F Exceeded Degrees o f Freedom P r o b . F Excee d e d Mean 1 1541673.00000 2871.62256 0.0 G 4 1102.12793 2.05290 0.097 E r r o r 67 536.86475 P 2 4429-30469 34\28398 0.000 1, 67 p < .01 PG 8 62.05311 0.48035 0.868 1, 67 p > .25 E r r o r 134 129.19458 >T 4 2348.20508 39.65923 0.000 1, 67 p < .01 TG 16 48.38062 0.81711 O.389 ^ > 67 P > .25 E r r o r 268 59.20955 FT 8 199-02002 3-68445 - 0.000 1, 67 P > .05 PT.G 32 56.93457 1.05403 0.389 4, 67 P ? .25 E r r o r 536 54.01616 S 1 28727.78125 245.95955 0.0 SG 4 205-46777 1.75916 0.147 E r r o r 67 116.79880 PS 2 2687-30664 31.42212 0.000 1, 67 p > .01 PSG 8 46.33594 0.54180 0.823 4, 67 P < .25 E r r o r 134 85.52274 TS 4 3285.36328 69.36961 0.000 1, 67 p u .01 TSG 16 49.46265 1.04439 0.410 4, 67 P ^ .25 E r r o r 268 47.36026 PTS 8 344,17090 8.40303 0.000 1, 67 P £- .01 PTSG 32 34.08765 0.83226 0.732 4, 67 .25 E r r o r 536 40.95763 N o t e . G = l e s i o n group. P = S t i m u l u s p a t t e r n . T = T r i a l . S = S t i m u l u s v e r s u s b a s e l i n e . 132 T a b l e 4 A n a l y s i s o f V a r i a n c e F T a b l e T r i a l s ' 1 - 5 f o r S I , S 2 , S3 and S4, E x p e r i m e n t I I I G e i s s e r Greenhouse C o n v e n t i o n a l F t e s t C o n s e r v a t i v e F t e s t Degrees o f Mean P r o b . F Degrees o f P r o b . F Source Freedom Square F E xceeded Freedom E x c e e d e d Mean 1 1047163.37500 1511.57788 0.000 G 4 1553.69531 2.24275 0.084 E r r o r 35 692.76172 P 3 2046.07813 19.28630 0.000 1, 35 p ^ .01 PG 12 232.12955 2.18805 0.017 4, 35 P ^ -05 E r r o r 105 106.08965 T 4 622.87695 12.22952 0.000 1, 35 p = .01 TG 16 76.99609 1.5H73 0.103 4, 35 p = .10 E r r o r 1 4 0 50.93225 PT 12 133.45215 2.54463 0.003 1, 35 P * -05 PTG 4 8 53.63557 1.02271 0.436 4, 35 P ^ .25 E r r o r 4 2 0 52.44452 S 1 13791.12500 152.33879 0.000 1, 35 p .01 SG 4 1310.72363 1 4 . 4 7 8 4 5 0.000 4, 35 p = .01 E r r o r .35 90.52930 PS 3 1765.04297 34.11252 0.000 1, 35 p = .01 PSG 12 1 1 6 . 1 6 2 4 3 2 . 2 4 5 0 4 0 . 0 1 4 4, 35 p =• .05 E r r o r 105 5 1 . 7 4 1 7 8 TS 4 836.51593 2 2 . 1 2 8 4 3 0.000 1, 35 p = .01 TSG 16 131.97778 3 . 4 9 1 2 1 0.000 4, 35 p ^ .05 E r r o r 1 4 0 37.80292 PTS 12 147.56216 4.52343 , - 0.000 1, 35 p = .01 PTSG 4 8 34.31079 1.05178 0.385 4, 35 p ^ .25 E r r o r 4 2 0 32.62173 N o t e . G = L e s i o n group. P = S t i m u l u s p a t t e r n . T = T r i a l . S = S t i m u l u s v e r s u s b a s e l i n e . 133 T a b l e 5 A n a l y s i s o f V a r i a n c e F T a b l e T r i a l s 1-30 f o r S I and S 2 , E x p e r i m e n t I I I G e i s s e r Greenhouse Conventional):- F t e s t C o n s e r v a t i v e F t e s t Degrees o f Mean P r o b . F Degrees o f P r o b . F Source Freedom Square F E x c e e d e d Freedom E x c e e d e d Mean 1 1709706.00000 1557-34145 ^0.0 G 4 974.76953 0.88790 . 0 .481 E r r o r 35 1097.83618 P 1 2533.57227 26.30316 0.000 PG 4 666.55615 6.92009 : 0.000 E r r o r 35 96.72193 T 14 601.82935 10.32044 0.0 1, 35 P <:.01 TG 56 90.02084 1.54372 0.617 4, 35 p > .10 E r r o r 490 5 8 . 3 1 4 2 9 PT 14 235.77065 4.06118 0.000 1, 35 P < .05 PTG 56 5 4 . 0 8 5 4 5 0.93163 0.617 4, 35 p >,25 E r r o r 490 58 .05476 S 1 7408.89063 103.21722 0.000 SG 4 523.55835 7-29397 0.000 E r r o r 35 71 -77959 PS 1 1191.18823 22.51860 0.000 PSG 4 III.3I622 2.10436 0.101 E r r o r 35 52.89796 TS 14 796.08862 23.43439 0.0 1, 35 P > .01 TSG • 56 93.56082 2 .75414 0.000 4, 35 P < .05 E r r o r 490 3 3 - 9 7 0 9 5 PTS 14 229.16656 7 .68754 0.000 1, 35 p < .01 PTSG 56 40.90227 1.37209 0 .044 4, 35 p > .25 E r r o r 490 29.81012 Note. ' G = L e s i o n group. P = S t i m u l u s p a t t e r n . T = T r i a l . S = S t i m u l u s 'versus b a s e l i n e . 134 T a b l e 6 A n a l y s i s o f V a r i a n c e F T a b l e T r i a l s 1-5 f o r S I , S2, S 3 and S4, E x p e r i m e n t I V A G e i s s e r Greenhouse C o n v e n t i o n a l F t e s t C o n s e r v a t i v e F t e s t Degrees o f Mean P r o b . F Degrees o f P r o b . F S o u r c e Freedom Square F E xceeded Freedom E x c e e d e d Mean 1 .613145.50000 2011.78638 0.000 G 4 678.36816 2.22579 0.105 E r r o r 19 304.77661 P 3 1870.96216 3 9 - 6 4 7 3 4 0.000 1, 19 P c.01 PG 12 75.53107 1.60057 0.117 4 , 19 P >.10 E r r o r 57 47.19009 T 4 434.98315 II.05209 0.000 1, 19 P i. .01 TG 16 48.08046 1.22163 0.272 4, 19 P ->.25 E r r o r 76 39-35753 FT 12 71.74576 1.78936 0.051 1, 19 P 5 . 1 0 PTG 4 8 41.46704 1.03420 0 . 4 2 1 4, 19 P >.25 E r r o r 2 2 8 40.09573 S 1 17150.29297 102.94807 0.000 SG 4 671.76367 4.03240 0.016 E r r o r 19 166.59167 PS 3 2 0 4 2 . 1 5 2 3 4 50.78313 0.000 1, 19 P < .01 PSG 12 1 0 4 . 1 4 8 1 3 2.58990 0.008 4 > 19 P >.05 E r r o r 57 40.21320 TS 4 735.61230 22.11537 0.000 1, 19 P i . . 0 1 TSG 16 42.50491 1 . 2 7 7 8 6 0.233 4, 19 P >-.25 E r r o r 76 3 3 . 2 6 2 4 7 PTS 12 66.'35774 2.03379 0.022 1, 19 P > .10 PTSG 4 8 3 4 . 3 6 4 9 9 1.05325 0.389 4, 19 P » .25 E r r o r 2 2 8 32.62759 Note. G = L e s i o n group. P = S t i m u l u s p a t t e r n . T = T r i a l . S = S t i m u l u s v e r s u s b a s e l i n e . 1 35 Table 7 Analysis of Variance F Table Trials 1-30 for SI and S2, Experiment IVA Geisser Greenhouse Conventional F test Conservative F test Source Degrees of Freedom Mean Square F Prob... F Exceeded Degrees of Freedom Prob. F Exceeded Mean G Error 1 629630.87500 4 724.39453 19 239.40674 2175.59155 2.50303 0.0 0.077 P PG Error 1 4 19 2183-24878 67.64032 52.60526 41.50247 1.28581 0.000 0.311 T TG Error 9 36 171 554.18994 58.10774 31.04771 17.84961 1.87156 0.000 0.004 i , 4, 30 30 p 4-.01 p ->.10 PT PTG Error 9 36 171 191.85025 35.23784 30.75040 6.23895 1.14593 0.000 0.278 1, 4, 30 30 P ^.05 P *.25 S SG Error 1 4 19 13157•12891 646.07397 212.57506 61.89403 3.03927 0.000 0.043 PS PSG Error 1 4 19 2359.37036 141.44482 40.95830 57.60420 3.45339 0.000 0.028 TS TSG Error 9 36 171 624.25903 41.10156 27.47084 22.72441 1.49619 -• 0.000 • 0.047 1, 4, 30 30 p ^..01 p >.10 PTS PTSG Error 9 36 171 289.94995 36.90442 23.40471 12.38853 1.57679 0.000 0.029 1, 4, 30 30 " p <..01 P * . i o Note. G = lesion group. P = Stimulus pattern. T = T r i a l . S = Stimulus versus baseline. 136 T a b l e 8 A n a l y s i s o f V a r i a n c e F T a b l e E x p e r i m e n t IVB G e i s s e r Greenhouse C o n v e n t i o n a l F t e s t C o n s e r v a t i v e F t e s t S o u r c e Degrees o f Freedom Mean Square F P r o b . F Excee d e d Degrees o f Freedom P r o b . F Exceeded Mean 1 1296232.00000 4490.42969 0.000 G 4 773-38477 2.67917 0.057 E r r o r 23 288.66528 P 2 924.51636 16.13194 0.000 1, 23 p <i..01 PG 8 125.67377 2.19289 0 .046 4, 23 p V .10 E r r o r 4 6 • 57-30966 T 9 269.24292 6.31120 0.000 1, 23 P t~ -05 TG 36 34.58127 0.81060 0.771 4, 23 p .25 E r r o r 207 42.66112 PT 18 300.06616 6 .69541 0.000 1, 23 p <L .05 PTG 72 27.38715 0.61109 0.994 4, 23 p ^ .25 E r r o r 414 44.81671 S 1 3348.76855 102.83417 0.000 SG 4 52.21161 1.60332 0.207 E r r o r 23 32.56474 PS 2 ' 1436.43604 44.31200 0.000 1, 23 p c.Ql PSG 8 58.12714 1.79314 0.103 4, 23 p ^-25 E r r o r 46 32 .41641 TS 9 '356.20605 12.24939 0.000 1, 23 p *--.01 TSG 36 23.82291 0 .81293 0.758 4, 23 p ^.25 E r r o r 207 29.07950 PTS 18 251.40016 9 .24454 0.000 1, 23 p i - . O l PTSG 72 20.73459 0.76246 0.921 4, 23 p J*. .25 E r r o r 4 1 4 27.19446 N o t e . G = L e s i o n group. P = S t i m u l u s p a t t e r n . T = T r i a l . S = S t i m u l u s v e r s u s b a s e l i n e . 137 Table 9 Analysis of Variance F Table Experiment V Conventional F test Geisser Greenhouse Conservative F test Degrees of Mean Prob. F Degrees of Prob • K Source Freedom Square F Exceeded Freedom Ex ceeded Mean 1 333328.81250 2591.05933 0.000 G 3 382.09717 2.92626 0.077 Error 12 - 130.57547 P 3 524.59375 8.58772 ' 0.000 1 P < .05 PG 9 132.84119 2.17464 '0.048 3 P 7 .10 Error • 3 6 61.08653 12 P T 4 769.04590 14.89722 0.000 ' 1 P < .01 TG 12 44.97955 0.87130 0.580 3 P .25 Error 48 51.62344 12 PT 12 •133.89517 3.35663 0.000 1 P < .05 PTG 36 24.80371 0.-62181 0.951 3 P > .25 Error. 144 39.88976 16 S 1 ' 15750.85547 . 81.71030 0.000 l P .01 SG 3 451.61987 2 .34286 0.125 3 P y .10 Error 12 192.76462 12 . PS 3 583.60132 10.46177 0.000 1 P c. .01 PSG 9 101.60066 1.82132 0.098 3 P > ,10 Error 36 55-78419 12 TS 4 . 974.86572 25.99059 0.000 1 P < .01 TSG 12 33.97491 0.90579 0 .548 3 P .25 ,Error 48 37-50841 12 PTS 12 74.94661 1.95930 0.032 1 P > .10 PTSG 36 ' 29.26898 0.76517 0.825 3 .P > .25 Error 144 38.25179 O.76517 12 Note. G = Lesion group. P = Stimulus pattern. T = T r i a l . S = Stimulus versus baseline. 138 T a b l e 10 A n a l y s i s o f V a r i a n c e F T a b l e E x p e r i m e n t I V e r s u s E x p e r i m e n t V G e i s s e r Greenhouse C o n v e n t i o n a l F t e s t C o n s e r v a t i v e F t e s t Degrees o f Mean P r o b . F Degrees o f P r o b . F Sou r c e Freedom Square F Exceeded Freedom Exce e d e d Mean 1 1154153-00000 1683.92969 0.000 E 1 22684.33203 33.09683 0.000 G 3 1592.32666 2.32323 0.739 E r r o r 39 685.39258 P 3 645.60010 5.51252 0.001 : 1, 39 P < .05 PE 3 301.10547 2.57102 0.058 1, 39 P > -05 PG 9 264.23438 2.25619 0.023 3, 39 p > .10 PEG 9 80.58594 0.68809 0 .718 3, 39 P > -25 E r r o r 11? 117.11514 T 4 611.19629 8.68986 0.000 1, 39 P < .01 TE 4 402.51660 5.72290 0.000 1, 39 P < -05 TG 12 120.93262 1 .71939 0.067 1, 39 P > . 1 0 TEG 12 52.57129 0.74745 0.704 3, 39 P > .25 E r r o r 156 70 .33440 PT 12 168 .76724 3-22181 0.000 1, 39 P > .05 PTE 12 84.31543 1.60960 0.085 1, 39 p > .10 PTG 36 20 .66644 0.39453 0.999 3, 39 P > .25 PTEG 36 47.15451 0.90019 0.638 3, 39 P y .25 E r r o r 468 52.38278 S 1 18373•23047 1 7 3 . 4 6 2 4 9 0.000 SE 1 4064.75000 38.37549 0.000 SG 3 1400.80078 13.22502 0.000 SEG 3 194 .48828 I.83617 0.157 E r r o r 39 105.92047 PS 3 767.37231 15-33582 0.000 1, 39 P < .01 PSE 3 136.82031 2 . 73433 0 . 047 1, 39 p > .10 PSG 9 135.15451 2 . 70104 0.007 3, 39 P > .05 PSEG 9 64.56683 1.29036 0.249 3, 39 p > . 10 E r r o r 117 50.03792 139 G e i s s e r Greenhouse C o n v e n t i o n a l F t e s t C o n s e r v a t i v e F Sou r c e Degrees o f Freedom Mean Square F P r o b . F Exceeded Degrees o f Freedom Prob...'F E x c e e d e d TS- 4 1095-66699 22 .14644 0.000 1, 39 P < .01 TSE 4 292.-33887 5-90897 0.000 1, 39 P < .05 TSG 12 73.28548 1 .48130 0.136 3, 39 p > .10 TSEG 12 51.88638 1.04877 0.408 3, 39 p > .25 E r r o r 156 49.47372 PTS 12 99.00098 2.47605 0 .004 1, 39 p > .10 PTSE 12 44.12695 1.IO363 0-355 1, 39 P > -25 PTSG 36 37.16254 0.92945 0.589 3, 39 P > -25 PTSEG 36 34.01476 0.85072 0.717 3, 39 p > .25 E r r o r 468 39-98340 Note. E = E x p e r i m e n t . G = . L e s i o n group*. Pir= S t i m u l u s p a t t e r n . T = T r i a l . S = S t i m u l u s v e r s u s b a s e l i n e . 140 T a b l e 1 1 " A n a l y s i s o f - V a r i a n c e F T a b l e T r i a l s t o C r i t e r i o n , E x p e r i m e n t V I C o n v e n t i o n a l F t e s t Degrees o f Mean P r o b . F S o u r c e Freedom Square F Exc e e d e d Mean 1 1 7 5 5 6 2.43750 473.42700 0 . 0 0 0 ' -G 4 2281.23633 6 . 1 5 1 6 5 0 . 0 0 1 S 1 1 1 0 2 . 4 9 6 0 9 2.97303 0.095 GS 4 2 4 6 . 2 4 7 0 7 0 . 6 6 4 0 4 0 . 6 2 2 E r r o r 30 3 7 0 . 8 3 3 0 1 Note. G = L e s i o n group. S = S t i m u l u s d i s p l a y . 1.41 T a b l e 12 A n a l y s i s o f V a r i a n c e F T a b l e A c q u i s i t i o n o f C o n d i t i o n e d S u p p r e s s i o n , Phase 2, E x p e r i m e n t V I G e i s s e r Greenhouse C o n v e n t i o n a l F t e s t C o n s e r v a t i v e s F t e s t Degrees o f Mean P r o b . F Degrees o f Pr o b . F So u r c e Freedom Square F Exceeded Freedom Exceeded Mean 1 1229020.00000 2935-41455 0.000 G 4 2 4 3 . 1 4 4 5 3 0.58073 0.679 L 1 927.75391 2.21586 0 . 147 GL 4 162.75781 0.38873 0.815 E r r o r 30 4 1 8 . 6 8 7 0 1 D 3 10520.89844 66.68654 0.000 1, 30 P L. .01 DG 12 335.55273 2.12689 0.023 4, 30 P .i. .10 DL 3 192 .28384 1 .21879 0.308 1, 30 P * .25 DGL 12 98 .63184 0.62518 0.816 4, 30 P ^ .25 E r r o r 90 157-76645 T 9 168 .64670 3 . 74184 0.000 1, 30 P i .05 TG 36 44 . 17935 0 . 98023 0.506 4, 30 P i. .25 TL 9 42.08289 0.93371 0.496 1, 30 P i. .25 TGL 36 26.53189 0.58868 0.972 4, 30 P i.25 E r r o r 270 45.07050 DT 27 71.26634 1.65173 0.020 1, 30 P * .10 DTG 108 49.80373 1.15429 0 .148 4, 30 P > .25 DTL 27 47 . 43619 1 . 09942 0.332 1, 30 P x .25 DTGL 108 4 3 . 4 2 4 6 8 1.00645 0 .468 4, 30 P 25 E r r o r 810 43.14656 S 1 229823.56250 494 .93945 0.000 SG 4 521.72168 I.12356 0.364 SL 1 18.44922 0.03973 0 . 843 SGL ' ' 4 652.55273 1.40531 0.256 E r r o r 30 4 6 4 . 3 4 6 6 8 DS 3 10026.03125 85 .24438 0.000 1, 30 P L.01 DSG 12 365.05811 3 . 10384 0.001 4, 30 P t- .05 DSL 3 17.81250 0.15145 0.929 1, 30 P A .25 DSGL 12 106.23209 0.90322 0 .548 4, 30 P \ .25 E r r o r 90 117.61514 C o n t i n u e d . . . 142 Geisser Greenhouse Conventional F test Conventional F test Degrees of Mean Prob. F Degrees of Prob. F Source . Freedom - Square F - - Exceeded •.Freedom Exceeded TS 9 141.18011 4.15387 0.000 1, 30 P > .05 TSG 36 44.85036 1.31961 0.114 4, 30 P > .25 TSL 9 67.61371 1.98936 0.041 1, 30 p > .10 TSGL 36 39.34288 1.15757 0.256 4, 30 P > .25 Error 2?0 33.98759 DTS . 27 29.87036 0.88482 O.636 1, 30 P > .25 • DTSG 108 31.37474 0.92938 0.679 4, 30 P > .25 DTSL 27 47.41072 1.40440 0.084 1, 30 p > .10 DTSGL 108 34.87178 1.03297 0.397 4, 30 P >-.25 Error 810 33-75862 Note. G = Lesion group. L = Light display. D = Session. T = Tr i a l s . S = Stimulus versus baseline. T a b l e 13 1 4 3 A n a l y s i s o f V a r i a n c e F T a b l e A c q u i s i t i o n o f C o n d i t i o n e d S u p p r e s s i o n Phase 2, A n a l y s i s 2,'Experiment-VI G e i s s e r Greenhouse C o n v e n t i o n a l F t e s t C o n s e r v a t i v e F t e s t Degrees o f Mean P r o b . F Degrees o f P r o b . F So u r c e Freedom " S q u a r e F E x c e e d e d Freedom E x c e e d e d Mean 1 1229020.00000 3042.25537 0.000 G 4 243.14453 0.60187 0.664 E r r o r 35 403.98315 D 3 10520.89844 69.21872 0.000 1, 35 P < .01 DG 12. 335.55273 2.20766 0.016 4, 35 P > -05 E r r o r 105 151.99496 T 9 168.64670 3.93421 0.000 1, 35 P .05 TG .36 44.17924 1.03062 0.426 4 ' 35 P > .25 E r r o r 315 42.86670 DT 27 71.26619 1.64583 0.021 1, 35 P > .25 DTG 108 49.80363 1.15017 0.152 4, 35 P > .25 E r r o r 945 43.30116 S 1 229823.56250 485-76489 0.000 1, 35 P c .01 SG 4 521.72168 1.10273 0.371 4, 35 P > .25 E r r o r 35 473.11670 DS 3 10026.03125 88.36386 0.000 1, 35 P c .01 DSG 12 365.05811 3.21742 0.001 ^, 35 P ^".05 E r r o r 105 113.46301 TS 9 141.17924 3.97010 0.000 1, 35 P 4-.05 TSG 36 44.85025 1.26123 0.152 4, 35 P > .25 E r r o r 315 35.56061 DTS 27 29.87022 0.87146 0.656 1, 35 P > .25 DTSG 108 31.37474 0.91535 0.716 4, 35 P > .25 E r r o r 945 34.27618 N o t e . .G= L e s i o n g r o u p . D = S e s s i o n . T = T r i a l s . S = S t i m u l u s v e r s u s b a s e l i n e . 144 Table 14 Analysis of Variance F Table Experiment B Geisser Greenhouse Conventional F test Conservative F test Degrees o f Mean P r o b . F Degrees o f P r o b . F S o u r c e Freedom Square F Exceeded Freedom Exceeded Mean 1 502206.37500 3094.12988 0.000 G 3 209.66129 1.29174 0.322 E r r o r 12 162.30940 P 3 904.50293 14.57647 0.000 1, 12 P L .01 PG 9 76.53297 1.23336 0.306 3, 12 P ^.25 E r r o r 36 62.05225 T 4 151.13422 3-99853 0.007 1, 12 P > .05 TG 12 67.25970 1.77948 0.079 3, 12 P *..10 E r r o r 48 37,79749 FT 12 75.17934 3.06759 0.001 1, 12 P y .05 PTG 36 45.24249 1.84606 0.006 3, 12 P *.10 E r r o r 144 24.50761 S 1 4080.38062 54.23123 0.000 SG 3 336.00146 4.46570 0.025 E r r o r 12 75.24042 PS 3 575.98389 10.82733 0.000 1, 12 P 4..01 PSG 9 43.00241 0.80836 0.612 3, 12 P E r r o r 36 53.19720 TS 4 271.36401 10.48343 0.000 .1, 12 P t.01 TSG . 12 68.24973 2.63665 0.009 3, 12 P A . 10 E r r o r 48 25.88504 PTS 12 84.40443 3.40933 0.000 1, 12 P .05 PTSG 36 48.35378 1.95314 0.003 3, 12 P .10 E r r o r 144 24.75693 Note. G = Lesion group. P = Stimulus pattern. T = T r i a l . S = Stimulus versus baseline. 145 Table 15 An a l y s i s of Variance F Table Appendix G Gei s s e r Greenhouse Conventional F t e s t Conservative F t e s t Degrees of Mean Prob. F Degrees of Prob. F Source Freedom Square F Exceeded Freedom Exceeded Mean 1 574998.75000 2371.28101 0.000 G 1 1245.58325 5-13675 0.047 E 10 • 242.48444 P' 2 195-93469 2.18633 0.138 1, 10 P < -25 PG 2 51-51758 0.57486 0.572 1, 10 P < .25 E r r o r 20 89.61803 T 9 95.80034 1.88875 0.064 1, 10 p < . 10 TG 9 104.73914 2.06498 0.041 , 1, 10 p < . 10 E r r o r 90 50.72156 PT 18 43.92273 0.99965 0.462 1, 10 p < .25 PTG 18 48.54578 1.10487 0.351 1, 10 P < .25 E r r o r :180 43.93810 S 1 2956.48657 86.70601 0.000 SG 1 371.23169 10.88725 0.008 E r r o r 10 34.09782 PS 2 275-14111 3.34088 0.056 1, 10 P < .25 PSG 2 26.35950 0.32007 0.730 1, 10 P < .25 E r r o r 20 82.35588 TS 9 298.00488 9-59878 0.000 1, 10 P > .05 TSG 9 98.87589 3.18481 0.002 " 1, 10 p < .10 E r r o r 90 31.04611 PTS 18 77.17101 2.60788 0.001 1, 10 p < .10 PTSG 18 18.I6296 0.61379 0.886 1, 10 P < .25 E r r o r / 180 29-59142 Note. G = Le s i o n group. P = Stimulus p a t t e r n . T = T r i a l s . S = Stimulus versus b a s e l i n e . 146. APPENDIX B C o u n t e r b a l a n c e d P r e s e n t a t i o n o f S t a t i o n a r y and " A p p a r e n t l y " M o v i n g l i g h t D i s p l a y s . The f o l l o w i n g s t u d y was c o n d u c t e d t o d e t e r m i n e i f t h e d i s r u p t i o n o f l i c k i n g on t h e f i r s t t r i a l s by SC, DP, and SP l e s i o n e d groups d e m o n s t r a t e d i n E x p e r i m e n t I I I was i n f l u e n c e d by t h e s p e c i f i c p a t t e r n o f t h e . d i s p l a y u s e d ( t h e " a p p a r e n t l y " moving 1 p e r l / l O s e c d i s p l a y ) . The SC and DP l e s i o n e d a n i m a l s d i s r u p t e d l i c k i n g on t h e f i r s t t r i a l s i n r e s p o n s e t o p r e s e n t a t i o n o f t h e a p p a r e n t l y moving a t 1 p e r l / l O s e c l i g h t s b u t d i d n o t d i s h a b i t u a t e t o t h e changes i n p a t t e r n o f t h e l l i g h t s . To e v a l u a t e t h e s i g n i f i c a n c e o f t h e m o t i o n o f t h e s t i m u l u s , t h e o r d e r o f s t i m u l u s p r e s e n t a t i o n was r e v e r s e d f o r a d d i t i o n a l n a i v e SH, SC, SP, and DP l e s i o n e d a n i m a l s . Method S u b j e c t s S i x t e e n n a i v e a n i m a l s were t e s t e d . F o u r a n i m a l s s u s t a i n e d e i t h e r SC, SP, DP, o r SH l e s i o n s . M a i n t e n a n c e o f t h e a n i m a l s and s u r g i c a l p r o c e d u r e were i d e n t i c a l t o t h a t d e s c r i b e d i n t h e p r e v i o u s s t u d i e s . A p p a r a t u s The a p p a r a t u s was i d e n t i c a l t o t h a t d e s c r i b e d i n t h e p r e v i o u s s t u d i e s . P r o c e d u r e The p r o c e d u r e was i d e n t i c a l t o t h a t d e s c r i b e d i n E x p e r i -ment I ; however, t h e o r d e r o f t h e s t i m u l u s p r e s e n t a t i o n was r e v e r s e d . The s t a t i o n a r y 1 p e r l / 5 s e c l i g h t d i s p l a y ( S i ) was p r e s e n t e d on 147. the f i r s t 15 t r i a l s , followed by the "apparently" moving 1 per 1/5 sec light display (S2) on t r i a l s 16-30, the stationary 1 per l/lO sec light display (S3) on t r i a l s 31-35, and the "apparently" moving 1 per l/lO sec light display (S4) on t r i a l s 36-40. A l l the animals i n the SC and DP lesioned groups were tested with the red f i l t e r s removed. Half the animals i n the SP and SH lesioned groups were tested with the f i l t e r s removed and half with them on. Results The results of the analysis of variance for the f i r s t five t r i a l s of light displays SI, S2, S3, and S4 are presented i n Table 14 of Appendix A. The four way interaction of pattern X t r i a l X stimulus X group was s t a t i s t i c a l l y reliable (F = 1. 95, df = 36» 144, p_ < .01) with the conventional F test. T tests were conducted to determine i f disruption of licking was reliably different from base-line for each of the lesioned groups on each t r i a l included i n the analysis. Trials on which disruption of licking was reliably d i f -ferent from baseline (t, c r i t i c a l , <* = .05/2, = 10.75) are marked by an asterisk i n Figure 25. The SH animals; reliably disrupted licking on the f i r s t three t r i a l s to the stationary 1 per 1/5 sec light display, habitua-ted, and dishabituated to the change from one light display to another. Responding to the light display (Si) was not as marked (in terms of amount of disruption) as to the moving light display presented,, but the overall pattern of results i s very similar to that of the previ-ous studies for this group. 148 A. Figure 25(a-d). Mean number of licks per 5 sec during baseline (B) and during presentation of the stimulus (S) for light displays SI, S2, S3, and S4. (a) SH, (b) SG, (c) SP, and (d) DP lesioned animals. The asterisk indicates the t r i a l s on which disruption of licking was-.statistically reliable. 149 A. F i g u r e 2 6 ( A - C ) . R e p r e s e n t a t i v e s e c t i o n s d e p i c t i n g t h e e x t e n t o f damage t o t h e S G and s u r r o u n d i n g t i s s u e f o r ( A ) S G , ( B ) S P and ( C ) D P l e s i o n e d a n i m a l s . 149 B. 150. The SC, SP, and DP l e s i o n e d a n i m a l s a l l r e l i a b l y d i s r u p t e d l i c k i n g on a t l e a s t t h e f i r s t t r i a l when t h e s t a t i o n a r y 1 p e r l/5 sec l i g h t d i s p l a y was p r e s e n t e d f i r s t . D i s r u p t i o n o f l i c k i n g d i d n o t r e l i a b l y o c c u r t o any o f t h e l i g h t d i s p l a y changes p r e s e n t e d . The l e s i o n s s u s t a i n e d by a n i m a l s i n t h e s e groups were v e r y s i m i l a r t o t h o s e o f t h e p r e c e d i n g s t u d i e s . R e p r e s e n t a t i v e s e c t i o n s i l l u s t r a t i n g t h e e x t e n t o f damage t o t h e SC and s u r r o u n d i n g t i s s u e a r e i n c l u d e d i n F i g u r e 26. The l e s i o n o f one s u b j e c t i n t h e SC gr o u p , however, was n o t a s e x t e n s i v e and d i d n o t i n c l u d e damage t o t h e d o r s a l tegmentum o r p r e t e c t a l n u c l e i . T h i s a n i m a l was more r e s p o n s i v e on t h e f i r s t two t r i a l s t h a n t h e o t h e r s u b j e c t s i n t h i s g r o up and a c c o u n t s f o r t h e enhanced r e s p o n d i n g on t h e f i r s t and s e c o n d t r i a l s r e l a t i v e t o t h e p r e c e d i n g s t u d i e s . (Compare p a n e l 1 o f F i g u r e s 12(b) and 26(b ) ) . D i s c u s s i o n The s t a t i o n a r y l i g h t s were l e s s s a l i e n t t h a n t h e moving l i g h t s f o r t h e SH c o n t r o l a n i m a l s . The SH a n i m a l s d i d n o t d i s r u p t l i c k i n g f o r as l o n g on any one t r i a l and t h e y r e q u i r e d f e w e r t r i a l s t o h a b i t u a t e t o t h i s l i g h t d i s p l a y t h a n t o t h e moving l i g h t d i s p l a y i n E x p e r i m e n t I . The SC, SP, and DP l e s i o n e d a n i m a l s were c a p a b l e o f r e s p o n d i n g t o t h e l i g h t s when f i r s t p r e s e n t e d . The p a t t e r n o f t h e d i s p l a y d i d n o t appear t o i n f l u e n c e t h e magnitude o f t h e r e s -ponse t o t h e l i g h t s o r t h e number o f t r i a l s r e q u i r e d t o h a b i t u a t e t o i t s r e p e a t e d p r e s e n t a t i o n by t h e SC l e s i o n e d a n i m a l s . These a n i m a l s , i n f a c t , a ppeared t o h a b i t u a t e more q u i c k l y t o t h e moving l i g h t s i n E x p e r i m e n t 1 t h a n t o t h e s t a t i o n a r y l i g h t s p r e s e n t e d f i r s t J. 5.1 . i n t h i s s t u d y . T h i s f i n d i n g i s , however, somewhat ambiguous as one a n i m a l ' s l e s i o n i n t h e group was i n c o m p l e t e . When t h i s a n i m a l ' s d a t a were i g n o r e d , t h e SG l e s i o n e d a n i m a l s d i d n o t d i f f e r i n r e s p o n s e t o t h e moving and s t a t i o n a r y l i g h t d i s p l a y s . 152. APPENDIX C The E f f e c t o f I n c r e a s e d I n t e n s i t y on O r i e n t i n g The SG l e s i o n e d a n i m a l s i n E x p e r i m e n t I I I were o b s e r v e d t o d i s r u p t t h e i r o n g o i n g b e h a v i o r i n r e s p o n s e t o t h e v i s u a l s t i m u l i when t h e i n t e n s i t y o f t h e l i g h t was i n c r e a s e d . The s t u d y d e s c r i b e d i n A p p e n d i x B s u g g e s t e d t h a t t h e p a t t e r n o f t h e l i g h t s may n o t have been i m p o r t a n t i n e l i c i t i n g t h e o r i e n t i n g r e s p o n s e f r o m t h e SC l e s i o n e d a n i m a l s . The SC l e s i o n e d a n i m a l s a l s o r e s p o n d e d t o t h e s t a t i o n a r y d i s p l a y when i t was p r e s e n t e d f i r s t . The c o n t r o l SH a n i m a l s were more r e s p o n s i v e t o t h e moving d i s p l a y t h a n t h e s t a t i o n -a r y when i t was p r e s e n t e d f i r s t . The f o l l o w i n g s t u d y a t t e m p t s t o f u r t h e r e v a l u a t e t h e i m p o r t a n c e o f s t i m u l u s c h a r a c t e r i s t i c s by f o c u s -s i n g on t h e i n t e n s i t y o f t h e l i g h t s p e r s e . Method S u b j e c t s S u b j e c t s were 6 n a i v e SC l e s i o n e d Long-Evans hooded r a t s and 6 n a i v e SH l e s i o n e d a n i m a l s . A p p a r a t u s The p r o c e d u r e was i d e n t i c a l t o t h a t d e s c r i b e d i n E x p e r i m e n t I e x c e p t t h a t t h e f o l l o w i n g s t i m u l i were p r e s e n t e d : ( S i ) A l l n i n e l i g h t s were i l l u m i n a t e d f o r 5 s e c . (S2) A l l n i n e l i g h t s were i l l u m i n a t e d and f l i c k e r e d a t 1 p e r l / l O s e c i n t e r l i g h t i n t e r v a l . (<S3) A l l n i n e l i g h t s were i l l u m i n a t e d and f l i c k e r e d a t 1 p e r l/5 s e c i n t e r l i g h t i n t e r v a l . L i g h t d i s p l a y S I was p r e s e n t e d on t r i a l s 1-10, S2 on t r i a l s 11-20, and S3 on t r i a l s 21-30. The r e d p l a s t i c f i l t e r s were n o t us e d . 153 R e s u l t s The r e s u l t s o f t h e a n a l y s i s o f v a r i a n c e c o m p a r i n g t h e SH and SC l e s i o n e d a n i m a l s a r e p r e s e n t e d i n T a b l e 15 o f A p p e n d i x A. The b e h a v i o r a l and h i s t o l o g i c a l r e s u l t s a r e p r e s e n t e d i n F i g u r e 2?. The groups d i f f e r e d r e l i a b l y i n amount o f l i c k i n g d u r i n g t h e p r e s e n t a t i o n o f t h e l i g h t s . The SC l e s i o n e d a n i m a l s r e l i a b l y d i s r u p t e d l i c k i n g on o n l y t h e f i r s t t r i a l . The SH a n i m a l s d i s r u p t e d , l i c k i n g - o n t h e f i r s t t h r e e t r i a l s t o S I , h a b i t u a t e d , and d i s h a b i t u a t e d t o t h e changes o f t h e s t i m u l u s d i s p l a y . The t r i a l s on w h i c h t h e a n i m a l s r e l i a b l y d i s r u p t e d l i c k i n g a r e marked by an a s t e r i s k i n F i g u r e 2? _(jt, oc = .05/2, = 6.99, d f = 10). Two a n i m a l s i n t h e SC group d i e d b e f o r e h i s t o l o g i e s were eon-r d u c t e d . F o r t h e r e m a i n i n g a n i m a l s t h e h i s t o l o g i c a l r e s u l t s were q u i t e s i m i l a r t o t h o s e p r e s e n t e d i n t h e p r e v i o u s s t u d i e s . The l e s i o n s a l w a y s i n c l u d e d damage t o t h e s u p e r f i c i a l and deep l a y e r s o f SC, p o s t e r i o r p r e t e c t a l n u c l e i , b r a n c h i u m o f SC, and d o r s a l tegmentum. I n most c a s e s t h e damage e x t e n d e d i n t o t h e c e n t r a l g r e y o v e r l y i n g t h e w h i t e m a t t e r o f t h e c o r t e x , and t h e , hippocampus.. The b e h a v i o r a l r e s u l t s were q u i t e s i m i l a r f o r a l l t h e a n i m a l s and d i d n o t v a r y i n any ..obvious way w i t h t h e e x t e n t o f damage t o e x t r a c o l l i c u l a r a r e a s i n c l u d e d I n t h e l e s i o n . D i s c u s s i o n I n t h i s s t u d y , t r i p l i n g t h e number o f l i g h t s p r e s e n t e d on each t r i a l r e s u l t e d i n o r i e n t i n g t o t h e l i g h t d i s p l a y s by t h e SC l e s i o n e d a n i m a l s . The d i s r u p t i o n was, however, o n l y r e l i a b l e on t h e 154 A . F i g u r e 27 ( A-C). ( A ) R e p r e s e n t a t i v e s e c t i o n s d e p i c t i n g t h e e x t e n t o f damage t o t h e SC and s u r r o u n d i n g t i s s u e , ( B ) Mean number o f l i c k s p e r 5 s e c d u r i n g t h e b a s e l i n e ( B ) and d u r i n g t h e p r e s e n t a -t i o n o f t h e s t i m u l u s ( S ) f o r t h e s o l i d ( S i ) a n d f l i c k e r i n g l i g h t d i s p l a y s S2 and S3, f o r SC l e s i o n e d a n i m a l s and (C) SH l e s i o n e d a n i m a l s . The a s t e r i s k i n d i c a t e s t h e t r i a l s on w h i c h d i s r u p t i o n o f l i c k i n g was s t a t i s t i c a l l y r e l i a b l e . - . SOL ID S 1 FLICKERING 1 SEC. S2 10 FLICKERING 1 SEC. S3 5 15 5 f i r s t t r i a l . T here was no f u r t h e r enhancement o f r e s p o n d i n g f o r t h e s e a n i m a l s r e l a t i v e t o t h e r e s p o n d i n g d e m o n s t r a t e d i n the p r e v i -ous s t u d i e s . The i n t e n s i t y o f t h e l i g h t d i s p l a y p e r se appears t o f a c i l i t a t e t h e e l i c i t a t i o n o f o r i e n t i n g i n d e p e n d e n t o f t h e p a t t e r n o f t h e d i s p l a y . 156. APPENDIX D E f f e c t o f V i s u a l a n d S u b c o r t i c a l L e s i o n s on Open F i e l d A c t i v i t y . S m i t h and Weldon (1976) have f o u n d t h a t a n i m a l s w i t h SG l e s i o n s a r e e x c e s s i v e l y a c t i v e i n an open f i e l d . These a u t h o r s examined r a t s w i t h SC l e s i o n s t h a t i n c l u d e d t h e s u p e r f i c i a l and deep l a y e r s o f t h e SC and s u b s t a n t i a l damage t o t h e d o r s a l tegmentum, c e n t r a l g r e y , p r e t e c t a l n u c l e i , and o v e r l y i n g p o s t e r i o r , . c o r t e x . The h y p e r a c t i v i t y t h e y o b s e r v e d i n t h e s e a n i m a l s may n o t have been a p p r o -p r i a t e l y a s c r i b e d t o t h e SC b u t r a t h e r t o t h e damage o f t h e u n d e r -l y i n g tegmentum and c e n t r a l g r e y a r e a s . The l e s i o n g r o u p s employed i n t h e p r e v i o u s e x p e r i m e n t s o f t h i s i n v e s t i g a t i o n p r o v i d e d an o p p o r t u n i t y t o examine t h e i n v o l v e -ment o f t h e s u p e r f i c i a l and.deep l a y e r s o f t h e SC i n change, i n t h e l e v e l o f l o c o m o t o r a c t i v i t y , and t o examine t h e i n v o l v e m e n t o f t h e e x t r a c o l l i c u l a r s t r u c t u r e s . I n a d d i t i o n , t h i s s t u d y p r o v i d e d a sup-p l e m e n t a r y e x a m i n a t i o n o f h a b i t u a t i o n o r waning o f a c t i v i t y o f t h e s e l e s i o n e d a n i m a l s b y . c o m p a r i n g a c t i v i t y a t t h e s t a r t o f t e s t i n g and a t t h e end o f t e s t i n g . Method S u b j e c t s S u b j e c t s were 12 r a t s w i t h s t r i a t e c o r t e x - a b l a t i o n s , . 1 2 w i t h SC l e s i o n s , 12 w i t h SP l e s i o n s , 12 w i t h DP l e s i o n s , a n d 12 SH o p e r a t e d c o n t r o l s . A l l o f t h e s e s u b j e c t s had been t e s t e d i n E x p e r i -ment I , I I I , o r I V . They were a l l o w e d a d l i b a c c e s s t o f o o d and w a t e r f o r a t l e a s t 2 weeks p r i o r t o t e s t i n g . 157-Apparatus A wooden open-field, 1.22 m square and .3 m high and painted white was divided into 16 equal squares by black lines (described previously by Valle and Bols, 1976). Illumination was provided by a 15 watt overhead lamp positioned i n the center of the f i e l d and providing an illumination level of .29 cd/m as measured by a Weston light meter i n the center of the floor of the f i e l d . Procedure The animals were dark adapted for at least 4 hours prior to testing (tested during the dark phase of the colony light-dark cycle between 2100-2400 hrs), and moved from the colony to testing room in light-tight carrying cases. The animals were placed i n the center of the open-field, facing the corner opposite the experimenter. The number of squares entered with both front paws and the number of rearing responses (both front paws off the floor) were counted for 10 min scored i n two 5 min blocks. The number of fecal boli deposited was also recorded. The floor of the f i e l d was cleaned with a dilute vinegar solution after each animal's test session. Results An analysis of variance compared the activity of the lesioned animals on the number of squares crossed and the number of rearing responses made i n the two 5 min blocks of the session. A separate analysis of variance compared the number of boli for each of the lesioned groups. Differences between the lesioned and SH animals on these measures were assessed by t tests or be Dunnett's t 158. f o r n o n - o r t h o g o n a l c o m p a r i s o n s . There were no s t a t i s t i c a l l y r e l i a b l e d i f f e r e n c e s between t h e l e s i o n e d a n i m a l s f o r t h e number o f b o l i ( F = 1.24, d f = 1, 37; p ^ .25). The means were SH = 4.00, SP = 5-25, ST = 4.11, SC = 2.92, and DP = 2.67-The SH, SP,_ahd-ST a n i m a l s ; - d i d t e n d t o h a v e - h i g h e r s c o r e s o n ' t h i s measure than- t h e SC and DP l e s i o n e d a n i m a l s ; however, t h e v a r i a b i l i t y w i t h i n t h e groups was q u i t e h i g h and t h e d i f f e r e n c e s were n o t r e l i a b l e . The l e s i o n e d groups d i f f e r e d m a r k e d l y i n t o t a l amount o f a c t i v i t y (number o f s q u a r e s c r o s s e d and number o f r e a r i n g r e s p o n s e s ) i n t h e open f i e l d ( F = 2.62, d f = 4, 37; £ - .05). The SH a n i m a l s a v e r a g e d a t o t a l o f 116.3, SC a n i m a l s 205.0,- SP a n i m a l s 116.5, DP a n i m a l s 151.0, and ST a n i m a l s 172.7 s q u a r e s c r o s s e d and r e a r i n g r e s p o n s e s i n t h e e n t i r e 10 min o f o b s e r v a t i o n . The SC, DP, and ST a n i m a l s were much more a c t i v e i n t h e open f i e l d t h a n t h e SH o p e r a t e d and SP l e s i o n e d a n i m a l s . The SG, DP, and ST l e s i o n e d a n i m a l s were s t a t i s t i c a l l y d i f f e r e n t f r o m SH a n i m a l s , w h i l e t h e SP l e s i o n e d a n i m a l s were n o t ( D u n n e t t ' s t , = .05/2, 5, 35 = 49-15). The number o f s q u a r e s c r o s s e d -and r e a r i n g r e s p o n s e s made i n th e f i r s t and s e c o n d h a l f o f t h e s e s s i o n d i f f e r e d m a r k e d l y between groups ( F = 8.04, d f = 1, 37, £ - .01). The l e s i o n e d a n i m a l s ' (SC, SP, DP, and ST) a c t i v i t y l e v e l s h a b i t u a t e d , i n t h a t t h e y r e l i a b l y c r o s s e d f e w e r s q u a r e s i n t h e s e c o n d h a l f o f t h e s e s s i o n , b u t t h e i r a c t i v i t y was n o t r e l i a b l y d i f f e r e n t i n t h e 2 h a l v e s o f t h e s e s s i o n (ty. = .05/2, = 10.98, d f = 1, 37). A l l t h e l e s i o n e d a n i m a l s a p p e a r e d t o h a b i t u a t e a c t i v i t y i n t h e open f i e l d more q u i c k l y t h a n 159. t h e SH o p e r a t e d a n i m a l s . A d i f f e r e n c e between a n i m a l s w i t h l a r g e l e s i o n s o f c o r t e x w h i c h i n c l u d e d a l l o f a r e a 1 7 , e x t r a s t r i a t e , and p a r t o f a r e a 7 and t h o s e w i t h l e s i o n s c o n f i n e d t o a r e a 1 7 was o b s e r v e d . i n h a b i t u a t i o n o f a c t i v i t y . The a n i m a l s w i t h l a r g e r l e s i o n s c l e a r l y were l e s s a c t i v e i n t h e s e c o n d h a l f o f t h e s e s s i o n . The a c t i v i t y o f a n i m a l s w i t h l e s i o n s c o n f i n e d t o a r e a 1 7 o n l y was d i s t r i b u t e d more e q u a l l y between t h e two h a l v e s o f t h e s e s s i o n . The number o f r e a r i n g r e s p o n s e s was d i s t r i b u t e d e q u a l l y between the two h a l v e s o f t h e s e s s i o n s and t h e d i f f e r e n c e s were n o t s t a t i s t i c a l l y r e l i a b l e f o r any o f t h e g r o u p s . The SC,'SP, and DP l e s i o n e d a n i m a l s , however, made v e r y few r e a r i n g r e s p o n s e s t h r o u g h o u t t h e e n t i r e s e s s i o n . The ST l e s i o n e d a n i m a l s and SH o p e r a t e d a n i m a l s made f a r more r e a r i n g r e s p o n s e s t h a n SC l e s i o n e d a n i m a l s . The ST l e s i o n e d a n i m a l s d i d n o t d i f f e r r e l i a b l y f r o m SH o p e r a t e d a n i m a l s , w h i l e a l l t h e SC l e s i o n e d a n i m a l s d i d on t h i s measure ( D u n n e t t ' s t , -05/2, 5 , 3 5 = 13.88). D i s c u s s i o n L e s i o n s o f t h e s u p e r i o r c o l l i c u l u s r e s u l t e d i n i n c r e a s e d a c t i v i t y i n t h e open f i e l d . The s u p e r f i c i a l l a y e r s were, however, n o t i n v o l v e d i n t h i s b e h a v i o r a l change, w h i l e t h e deep l a y e r s and d o r s a l tegmentum were. T h i s f i n d i n g s u p p o r t s t h e n o t i o n t h a t t h e deep l a y e r s ' r o l e i n b e h a v i o r can be d i s s o c i a t e d f r o m t h e s u p e r f i c i a l l a y e r s ' (Casagrande & Diamond, 197^ ; I n g l e & Spr a g u e , 1 9 7 5 ) -The a c t i v i t y l e v e l s o f t h e SP, DP, and SC l e s i o n e d a n i m a l s a l l changed as a f u n c t i o n o f t i m e ( i . e . , t h e r e was a marked r e d u c t i o n 16 0 i n a c t i v i t y d u r i n g t h e s e c o n d h a l f o f t h e s e s s i o n ) . The SH o p e r a -t e d a n i m a l s were n e v e r as a c t i v e as t h e l e s i o n e d a n i m a l s h u t t h e i r l e v e l s o f a c t i v i t y was s u s t a i n e d t h r o u g h o u t t h e s e s s i o n . T h i s f i n d -i n g , o f c o u r s e , p a r a l l e l s t h e r e s u l t s f o r f a s t e r h a b i t u a t i o n o f o r i e n t i n g t o s p e c i f i c v i s u a l s t i m u l i f o r SC, SP, and l a r g e p o s t e r i o r c o r t e x l e s i o n s r e p o r t e d i n t h e main body o f t h i s r e p o r t . The SC l e s i o n e d a n i m a l s d i f f e r e d m a r k e d l y f r o m t h e SH c o n t r o l s and ST l e s i o n e d a n i m a l s i n t h e amount o f r e a r i n g i n t h e open f i e l d . The SC l e s i o n e d a n i m a l s v e r y r a r e l y r e a r e d i n t h e open f i e l d . The SH_and ST l e s i o n e d a n i m a l s s p e n t a g r e a t d e a l o f time r e a r i n g and t h i s a p p e a r e d . t o be i n r e s p o n s e t o e x t r a n e o u s n o i s e s and was o f t e n c o r r e l a t e d w i t h b o u t s o f s n i f f i n g . The SC l e s i o n e d a n i -m als' e x c e s s i v e a c t i v i t y i n t h e open f i e l d r e l a t i v e t o c o n t r o l a n i m a l s may have been due t o t h e f a c t t h a t t h e y were n o t d i s t r a c t e d by e x t r a n e o u s n o i s e s and p e r h a p s o l f a c t o r y s t i m u l i t h a t t h e i n t a c t a n i m a l s a p p e a r e d t o r e s p o n d t o by r e a r i n g and s n i f f i n g . R a t h e r , t h e SC l e s i o n e d a n i m a l s p e r s i s t e d i n t h e i r l o c o m o t o r a c t i v i t y . M a r s h a l l (1978) a l s o f o u n d SC l e s i o n e d a n i m a l s were more a c t i v e i n t h e open f i e l d and t h a t , • u n l i k e t h e SH o p e r a t e d ' a n i m a l s , t h e y d i d no.t e x p l o r e . o b j e c t s i p l a c e d \ i n . t h e t e s t c h a m b e r by r e a r i n g and making l a t e r a l l y d i r e c t e d i n v e s t i g a t o r y head movements. I n summary, t h e s u p e r f i c i a l l a m i n a e o f t h e s u p e r i o r c o l l i c u l u s were n o t i m p l i c a t e d i n t h e e x c e s s i v e a c t i v i t y i n t h e open f i e l d d e m o n s t r a t e d f o r a n i m a l s w i t h l e s i o n s o f t h e deep l a m i n a e and. a d j a c e n t tegmentum, B o t h l e s i o n s , however, r e s u l t e d i n f a s t e r 161 h a b i t u a t i o n o f a c t i v i t y and i n t h e l o s s o f r e a r i n g i n t h e open f i e l d . L a r g e l e s i o n s o f t h e c o r t e x w h i c h i n c l u d e d a r e a 17, t h e e x t r a s t r i a t e c o r t e x , a n d a r e a 7 o f t h e c o r t e x , o r l e s i o n s c o n f i n e d p r i m a r i l y t o a r e a 17 r e s u l t e d i n i n c r e a s e d a c t i v i t y i n t h e open f i e l d b u t nob i m p a i r m e n t o f r e a r i n g i n t h e open f i e l d . 162. APPENDIX E The Effect of Geniculo-Strlate and Tecto-Pulvinar Inputs to the Cortex on Orienting The effect of cortical lesions on orienting.behavior and dishabituation were d i f f i c u l t to evaluate i n the preceding studies as the behavioral effect was not systematically correlated with lesion size and placement. Animals whose lesions included a l l of areas 17, 18, and 18A did not d i f f e r from control animals; however, i f the lesion included a l l of areao7, as well as., areas 17, 18, and 18A, the animals oriented to the novel light display but habituated within a few t r i a l s and did not dishabituate to the changes i n the ligh t display. Large lesions of the cortex which include areas 17, 18, 18A,and 7, as well as lesions of the superficial or deep laminae of the SC, mayrresult i n faster habituation to the light displays and the absence of dishabituation to changes i n the light displays. The area of cortex removed by the lesions of the posterior cortex includes the terminals of the geniculo-striate system and the major projection of the SC to the cortex via the NLP (the tecto-pulvinar system). This study was conducted to determine i f the changes i n habituation and dishabituation seen after large cor t i c a l lesions were due to the loss of the input from the superficial laminae of the SC. Method Subjects Twelve naiveJ animals were tested. Two animals received large b i l a t e r a l lesions, 2 received striate cortex lesions, 4 received 163 nucleus l a t e r a l i s posterior (NLP) lesions, and 4 received NLP and striate cortex (NLP+ST) lesions. Animal maintenance and housing were identical to Experiment I. Apparatus The apparatus was identical to that described i n Experiment I. The "apparently" moving and stationary light displays with the red plastic f i l t e r s were presented as i n Experiment I. Procedure Histological and testing procedures were identical to Experiment I. Surgical procedures were different from Experiment I in the following ways: Largesbilateral cortex (LC) lesions were aspirated as i n Experiment I and an attempt-was made to include all-of- areas 17, 18, 18A,and 7. Striate cortex (ST) lesions were aspirated as i n Experin ment I. The coordinates were those described by Hughes (1977). Nucleus Lateralis Posterior (NLP) lesions were made bil a t e r a l l y with an electrolytic lesion maker by a twisted wire electrode insulated except for the area of the tip (approximately .5 mm). Tissue destruction was accomplished by passage of an anodal DC current (.2 mamp) for 20 seconds. The coordinates were those, described by-Hughes (1977). Nucleus lateralis posterior and striate cortex (NLP+ST) lesions were made as described above. 164 Results The effects of the lesions on orienting, habituation, and dishabituation i n response to the "apparently" moving light display were presented in Figure 24. S t a t i s t i c a l analyses were not conducted on these data.' The individual animals' performance was assessed by comparison to the averaged results of Experiment I. The rate of habituation was determined by a ratio.. (the number of l i c k s during baseline - the number of licks during the light displays '/ the number of l i c k s during baseline). The animal was considered to have habitua-ted to the display when a ratio of zero was attained on two successive t r i a l s . The animals with lesions which included a l l of areas 17, 18, 18A,and 7 (i-e., complete posterior decortication) habituated to the repeated presentation of the lights on approximatelythe third t r i a l and did not dishabituate to any of the light displays-changes. The ani-mals with lesions confined to area 17 only disrupted licking in res-ponse to light display SI, habituated to i t s repeated presentation, and dishabituated to each of the changes in the light display. These-animals did not habituate as quickly to light display SI as the SH animals of Experiment I. They required an average of 9 t r i a l s com-pared to an average of 6 for the ST animals in Experiment I. The animals with lesions of the NLP, were quite similar to the ST lesioned animals in this study. They disrupted licking in response to light display SI, habituated to i t s repeated presentation, and dishabituated to the changes in the light display. These animals 1 6 5 habituated to SI i n an average of 8 t r i a l s . Unfortunately 2 of the animals which sustained NLP+ST lesions died prior to the behavioral tests. The remaining animals with NLP+ST lesions behaved l i k e the SC lesioned animals. They disrupted licking in response to light display SI, habituated to the repeated presentation of the light display i n an average of 4 t r i a l s , and did not dishabituate to any of the changes i n the light display. A l l of the animals in this study oriented to the presenta"-s tion of SI on t r i a l 1 . The animals disrupted licking, l i f t e d their heads from the water spout,and looked at the light display. The extent of the head l i f t , postural adjustment," and duration of looking at the lights was quite similar to the ST animals observed in Experi-ment I. Discussion As can be seen in Figure 24, complete NLP lesions did not impair dishabituation to the changes in the visual display. There-fore the projections from the superficial layers of the SC to the cortex per se are not responsible for the behavioral change. It appears from these preliminary results that both the striate cortex, the superficial laminae of the SC,and i t s cortical projections are involved in dishabituation. This was confirmed by the NLP+ST lesioned animals. Like the SP lesioned animals and the large cortical lesion group, these subjects oriented on the f i r s t t r i a l s but did not dis-habituate to any of the stimulus changes. The same relationship held for the rate of habituation for these animals. The SP and large 1:66 c o r t i c a l l e s i o n e d a n i m a l s and t h e NLP p l u s s t r i a t e a n i m a l s ' r e q u i r e d f e w e r t r i a l s t o h a b i t u a t e t o t h e f i r s t s t i m u l u s p r e s e n t e d . The r a t e o f h a b i t u a t i o n f o r NLP l e s i o n e d a n i m a l s and f o r ST l e s i o n e d a n i -mals was n o t m a r k e d l y d i f f e r e n t f r o m SH c o n t r o l s , b u t t h e y appeared t o r e q u i r e more t r i a l s . The above f i n d i n g s a r e o f i n t e r e s t i n l i g h t o f t h e p r o -p o s a l t h a t i n t e r a c t i o n s between t h e two m a j o r v i s u a l systems may be o f c o n s i d e r a b l e i m p o r t a n c e i n t h e s e f u n c t i o n s . L e s i o n s o f t h e a r e a s i n w h i c h t h e g e n i c u l o - s t r i a t e systemcand t e c t o - p u l v i n a r system o v e r -l a p r e s u l t e d i n an i m p a irment o f d i s h a b i t u a t i o n ; however, s i m p l y e l i m i n a t i n g one o f t h e s ystems' i n p u t s t o t h e s e a r e a s d i d n o t a f f e c t d i s h a b i t u a t i o n . 167. APPENDIX F: F i g u r e 28. 168. Figure 28. A histological reconstruction of the superior colliculus and surrounding structures. Abbreviations: SN = substantia nigra, FOR = reticular formation, HI ^hippocampus, GD = dentate gyrus, CG = central grey, GCS = commisure of the superior colliculus, SGS = stratum griseum superficial, SO = stratum opticum, SGM = stratum griseum mediale, SAM = stratum album mediale, SGP = stratum griseum profundum, and SAP = stratum album profundum. CCS S G S ] S U P E R F I C I A L soj L A M I N A E SGM SAM D E E P SGP L A M I N A E SAP ON vO 

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