Prefrontal circuits underlying cognitive flexibility
Timothy Spellman (University of Connecticut Medical School)
Hosted by the Circuit Neuroscience research group (CNS)
During his PhD with Josh Gordon and postdoc with Connor Liston Tim has undertaken a number of exciting projects to elucidate how PFC and hippocampal circuits contribute to behaviour. If you would like to chat to him before/after the talk then please contact Paul Anastasiades.
Cognitive flexibility, the ability to alter one’s strategy according to changing stimulus-response-reward relationships, is critical for acquiring and updating learned behavior. Attentional set-shifting, a test of cognitive flexibility, has been shown to critically involve the prefrontal cortex (PFC). It remains unclear, however, what specific role PFC neurons play and how they interact to support set-shifting. One widely held view is that prefrontal neurons bias sensorimotor responses by mediating attention. Another known function of PFC neurons is to respond to the outcomes of recent actions, and these neurons may support set-shifting through a feedback monitoring role. Using optogenetics and 2-photon calcium imaging, we present evidence that, while PFC activity does encode attentional sets, this activity does not bias sensorimotor responses. Rather, PFC activity enables set-shifting by encoding trial feedback information, and we identify a circuit-level mechanism that supports feedback monitoring through persistent, recurring activity bridging multiple trials. These studies revealed another surprising functional property of PFC cells, namely that their task engagement did not vary with their efferent projection targets. Instead, representations of trial feedback formed a topological gradient, with cells more strongly selective for feedback information located further from the pial surface and receiving denser afferent inputs from the anterior cingulate cortex. Together, these findings identify a critical role for deep PFC projection neurons in enabling set-shifting through behavioral feedback monitoring.
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