Fig. 1.

Schematic of the experimental design along with the two analyses methods for reversal learning. Rats were pretrained to touch the screens for food reward (see Methods). Immediately following pretraining, discrimination was conducted (mean duration 4–5 days, Table 1). Following discrimination training, rats were split into treatment groups and RU38486 treatment (60 min before training) and/or restraint stress (30 min before training) were given on the three subsequent days. The rats were tested for reversal learning immediately following these three treatment sessions. In the early/late analysis (panel A), reversal learning was analyzed in relationship to a given rat’s performance on the task irrespective of treatment (see Section 2 for details on early vs. late distinction). While the majority of rats were in the early phase of reversal learning during treatment, six of them progressed to the late phase for days 2 or 3 of reversal testing. For the ‘during manipulation’ (DM) and ‘after manipulation’ (AM) analysis (panel B), performance of the rats was analyzed separately for sessions during the manipulation (i.e., the first 3 days of reversal) vs. after the manipulation (all subsequent days). All rats required at least one AM session to complete reversal learning.