UBC Theses and Dissertations
Differential effects of basolateral amygdala inactivation on cue-induced reinstatement and extinction of food-seeking behavior McLaughlin, Ryan Joseph
Reinstatement of previously extinguished instrumental responding for drug related cues has been used as an animal model for relapse of drug abuse, and is disrupted by inactivation of the basolateral amygdala (Bl_A). However, the role that the BLA plays in reinstatement for natural rewards is currently unknown. In Experiments 1A and 1B, rats with bilateral cannulae implanted into either the caudal or rostral BLA were trained to press a lever to receive delivery of food reward paired with a complex light/tone conditioned stimulus (CS). Following initial training, they underwent extinction of lever pressing in the absence of the CS. Reinstatement of extinguished lever pressing was measured during response-contingent presentations of the CS alone. Rats receiving saline infusions into the caudal or rostral BIA displayed a significant increase in lever pressing during reinstatement sessions relative to their last day of extinction training. Inactivation of these subregions with bupivacaine did not attenuate responding for the CS in the absence of food delivery, and in fact, caudal BLA inactivation potentiated responding relative to vehicle controls. Analysis of within-session responding revealed that caudal BLA inactivation retarded extinction of lever pressing in response to the CS. In a separate series of experiments, inactivation of the caudal BLA on day 1 or day 2 of extinction training significantly disrupted consolidation of extinction learning on the following day. These data suggest that neural circuits which underlie cue-induced reinstatement for drug-related stimuli are different from those which mediate responding for conditioned reinforcers associated with natural rewards. Moreover, they suggest that the caudal BLA may play a role in extinction of instrumental responding for conditioned reinforcement in the absence of primary reinforcement.
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