Different contributions of somatostatin- and parvalbumin-expressing neurons to flexible representation of task variables in rodent prefrontal cortex

Abstract

Neurons in the prefrontal cortex (PFC) are selectively responsive to variables that are relevant to a task at hand. To investigate how different interneuron subtypes contribute to such flexible representation of task variables, we examined discharge characteristics and inactivation effects of somatostatin (SOM)- and parvalbumin (PV)-expressing neurons in the mouse medial PFC during a probabilistic classical conditioning task. SOM neurons showed strong cue-related activity predicting an upcoming reward or punishment, and its inactivation suppressed cuerelated, but not outcome-related, activity of nearby pyramidal neurons. By contrast, PV neurons showed strong outcome- and cue-related responses after outcome delivery, and its inactivation suppressed both cue- and outcome-dependent responses of pyramidal neurons after, but not before, trial outcome. In addition, inactivation of PV, but not SOM, neurons delayed reversal of cue-related responses in neighboring pyramidal neurons when cue-outcome contingency was reversed. These results suggest different contributions of SOM and PV neurons to maintaining significant sensory information and evaluating trial outcome in reference to expected outcome.