Distinct roles of parvalbumin- and somatostatin-expressing neurons in flexible representation of task variables in the prefrontal cortex

Abstract

A hallmark of prefrontal cortex (PFC) is flexible representation of task-relevant variables. To investigate roles of different interneuron subtypes in this process, we examined discharge characteristics and inactivation effects of parvalbumin (PV)- and somatostatin (SOM)-expressing neurons in mouse PFC during probabilistic classical conditioning. We found activity patterns and inactivation effects differ between PV and SOM neurons. SOM neurons conveyed cue-associated quantitative value signals until trial outcome, while PV neurons maintained valence signals even after trial outcome. Also, PV, but not SOM, neurons showed homogeneous bidirectional responses to reward and punishment, and PV, but not SOM, neuronal inactivation affected outcome responses and activity reversal of pyramidal neurons. Modeling suggests bidirectional outcome responses of PV neurons as an efficient mechanism for controlling synaptic plasticity for rapid cue-outcome contingency learning. Our results suggest primary roles of PFC SOM neurons in maintaining value information as working memory and PV neurons in rapid value updating.