Specialized coding patterns among dorsomedial prefrontal neuronal ensembles during conditioned reward seeking.

Non-overlapping cell populations within dorsomedial prefrontal cortex (dmPFC), defined by gene expression or projection target, control dissociable aspects of reward seeking through unique activity patterns. However, even within these defined cell populations considerable cell-to-cell variability is found, suggesting that greater resolution is needed to understand information processing in dmPFC. Here we use two-photon calcium imaging in awake, behaving mice to monitor the activity of dmPFC excitatory neurons throughout Pavlovian sucrose conditioning. We characterize five unique neuronal ensembles that each encode specialized information related to a reward, reward-predictive cues, and behavioral responses to reward-predictive cues. The ensembles differentially emerge across learning, and stabilize after learning, in a manner that improves the predictive validity of dmPFC activity dynamics for deciphering variables related to behavioral conditioning. Our results characterize the complex dmPFC neuronal ensemble dynamics that relay learning-dependent signals for prediction of reward availability and initiation of conditioned reward seeking.