Prelimbic cortex neural encoding dynamically tracks expected outcome value.

Animals must modify their behavior based on updated expected outcomes in a changing environment. Prelimbic cortex (PrL) neural encoding during learning predicts, and is necessary for, appropriately altering behavior based on a new expected outcome value following devaluation. We aimed to determine how PrL neural activity encodes reward predictive cues after the expected outcome value of those cues is decreased following conditioned taste aversion. In one post-devaluation session, rats were tested under extinction to determine their ability to alter their behavior to the expected outcome values (i.e., extinction test). In a second post-devaluation session, rats were tested with the newly devalued outcome delivered so that the rats experienced the updated outcome value within the session (i.e., re-exposure test). We found that PrL neural encoding of the cue associated with the devalued reward predicted the ability of rats to suppress behavior in the extinction test session, but not in the re-exposure test session. While all rats were able to successfully devalue the outcome during conditioned taste aversion, a subset of rats continued to consume the devalued outcome in the re-exposure test session. We found differential patterns of PrL neural encoding in the population of rats that did not avoid the devalued outcome during the re-exposure test compared to the rats that successfully avoided the devalued outcome. Our findings suggest that PrL neural encoding dynamically tracks expected outcome values, and differential neural encoding in the PrL to reward predictive cues following expected outcome value changes may contribute to distinct behavioral phenotypes.