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Roles of medial prefrontal cortex subregions in modulation of active and inhibitory action selection during aversively-motivated behaviours

University of British Columbia

Decision making in stressful and potentially aversive situations is an evolutionary trait functionally vital to avoid dangerous situations. It can either require action performance to actively avoid negative outcomes, or behavioural suppression to stay safe from danger. Failure to coordinate behaviour discrimination in real-life conflicting threatening situations can lead to aversive consequences because of improper inhibition of motor output when action is needed or, vice versa, when defensive actions are performed instead of withheld. These disruptions of appropriate functioning in avoidance behaviours can lead to improper action selection and increase negative outcomes as seen in disorders such as substance abuse, anxiety and depression. It has already been shown that striatal regions (namely the core and shell of the nucleus accumbens) are involved in regulation of avoidance behaviours with distinct roles in suppression and promotion of behaviour. Following the cortico-striatal connections with the prefrontal cortex (PFC), we investigated how active and inhibitory avoidance are controlled by the prelimbic cortex (PL) and infralimbic cortex (IL), which have been differentially implicated in instrumental response acquisition and expression. We also probed the extent to which the contribution of these regions is restricted to responding that is aversive and flexible. Separate groups of animals were trained to criteria on three distinct tasks and learned to avoid foot-shock delivery or to obtain sucrose by performing or suppressing lever-press behaviour. Pharmacological inactivation of these prefrontal regions revealed a role for PL in facilitating promotion and inhibition of goal- directed actions to oppose prepotent responding only when response allocation is under flexible conflicting conditions. IL inactivation, instead, was found to be necessary to refine action selection by inhibiting inappropriate responses while promoting instrumental active behaviour through suppression of fearful reactions. These results add a link in the neural network of avoidance processing and help further our understanding of how conditioned instrumental behaviours in threatening situations are processed by cortical regions and how pathological avoidance can arise in neuropsychiatric disorders.

Text

2019-08-09

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/71267

Psychology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/4.0/