Figure 7.

WCST analog used in the cell-recording study. A, In each trial, a start cue appeared when an intertrial interval was over. The bar pressing changed the start cue to a fixation point. If the monkey kept pushing the bar and maintained its gaze on the fixation point for 700 ms, a sample stimulus replaced the fixation point. If the monkey maintained eye fixation and bar press for another 630 ms, three test items appeared (to the left, right, and below the sample). The relevant rule for matching (matching by shape or matching by color) was consistent within a block of trials, and it changed without any notice to the monkey when a criterion of 85% correct performance was achieved. The relevant rule was not cued and the monkeys were only able to identify it by applying a rule and then interpreting the reward or error feedback in the context of the applied rule. B, Free-reward trials. In each trial the bar pressing changed the start cue to a fixation point, if the monkey maintained eye fixation and bar pressing for 630 ms, instead of the sample onset, a reward (the same type and amount as the reward in ordinary trials) was given. C, The extent of lesioned area (gray shading) on ventral view of the brain in OFC group. Single-cell recording was conducted in the area depicted in dark blue color.