Ventromedial prefrontal parvalbumin neurons are necessary for initiating cued threat avoidance

Abstract

ABSTRACTThe ventromedial prefrontal cortex (vmPFC) is essential for regulating the balance between reactive and adaptive response. Reactive, hard-wired behaviors – such as freezing or flight – are feasible in some situations, but in others contexts an acquired, adaptive action may be more effective. Although the vmPFC has been implicated in adaptive threat avoidance, the contribution of distinct vmPFC neural subtypes with differing molecular identities and wiring patterns is poorly understood. Here, we studied vmPFC parvalbumin (PV) interneurons in mice as they learned to cross a chamber in order to avoid an impending shock, a behavior that requires both learned, adaptive action and the suppression of cued freezing. We found that vmPFC PV neural activity increased upon movement to avoid the shock, when the competing freezing response was suppressed. However, neural activity did not change upon movement toward cued rewards or during general locomotion, conditions with no competing behavior. Optogenetic suppression of vmPFC PV neurons delayed the onset of avoidance behavior and increased the duration of freezing, but did not affect movement toward rewards or general locomotion. Thus, vmPFC PV neurons support flexible, adaptive behavior by suppressing the expression of prepotent behavioral reactions.