Stable and dynamic response population coding in prefrontal cortex

Prefrontal cortex (PFC) plays a key role in several goal-directed processes. PFC cells encode response choices across periods that require future actions to be kept in memory until their execution and monitor their outcome after execution. Great attention has been given to characterize how single cells interact to represent information across time and cognitive processes according to a stable or dynamic scheme. Nevertheless, little is still known about the specificity of these schemes for distinct cognitive processes and whether different PFC areas might represent the same information adopting different schemes. We investigated the response population coding proprieties of Dorsolateral (PFdl), Orbital (Fpo) and Frontopolar (PFp) prefrontal cortex across different task epochs of a rule-based task. In this task, two rhesus monkeys were trained to make a saccadic response toward one of two peripheral targets according to a specific rule associated with a visual cue. We focused our analysis on the delay period (DP), where the response is generated and maintained in memory and the feedback period (FP), where the monkey has reached the selected target waiting to know the outcome of his choice. We observed that PFdl encodes response during DP and FP with distinct coding schemes: static during the DP and dynamic in FP. A comparison of population coding during FP highlighted that the coding scheme was dynamic in PFdl and PFo compared to PFp, where the representation was static.