Prelimbic cortex integrates behavioral context with task-coding during spatial working memory maintenance

Abstract

Spatial working memory (SWM) is the ability to hold information on-line for future use. Numerous studies have investigated the prefrontal mechanisms that support SWM processes, but it is not fully understood what spatially relevant representations are supported during memory maintenance. Using in vivo electrophysiological recordings from rodent prelimbic (PL) and anterior cingulate cortices (ACC) (two sub- regions of the medial prefrontal cortex that have dissociable functional roles in behavior), we have replicated the finding that the mPFC exhibits firing rate related changes that may be related to maintenance processes. In line with previous work examining mPFC activity, we demonstrate that PL cortex population activity discriminates between the end of the delay and inter-trial interval, suggesting that PL plays a role in task-coding. Furthermore, PL cortex discriminates between the early and late portions of the delay, and the early and late portions of the ITI, possibly reflecting preparatory processes. Finally, we are the first to our knowledge to report that PL cortex firing rate distinguishes between trial-types (sample L-choice R vs sample R-choice L) on the delayed non-match to position task during the early, but not late delay period. These findings suggest that PL cortex integrates task-coding and behavioral context during SWM maintenance.