Delay activity in avian prefrontal cortex – sample code or reward code?

In the current study, we examined whether delay activity in the avian equivalent of the prefrontal cortex (PFC) represents a neural correlate of a to‐be‐remembered sample stimulus or an upcoming reward. Birds were trained on a directed forgetting paradigm in which sample stimuli (red and white) were either followed by a cue to remember (high‐frequency tone) or a cue to forget (low‐frequency tone). The task also incorporated a differential outcomes procedure in which a correct response on the memory test following a red (remember) sample was rewarded with food, but correct responses on the memory test following the white (remember) sample were not. If delay activity represents a sample code, then it should be seen on both red‐remember and white‐remember trials. On the other hand, if delay activity represents a reward code, then delay activity should be seen only on red‐remember trials, but not white‐remember trials. Our findings suggest that activity in the avian PFC represents the outcome associated with each sample (reward or no reward) rather than memory for the sample itself.