Figure 1.

Behavioral task and recording sites. The animal has to search by trial and error for the correct target. A, Description of trial events. A trial starts with a touch on the lever and onset of central fixation spot. After a delay period with eye fixation on the central spot, all four targets switch on and the animal makes a saccade toward and touches one of them. All targets switch off, and the feedback is given (no reward: negative; reward: positive). The following trial starts after an intertrial interval (ITI). B, Example of successive problems. In the first problem, the monkey discovers the solution in two trials (search period). After discovery, the animal is allowed to repeat the response (repetition period) (INC, incorrect; CO1, first correct; COR, correct in repetition). A signal to change (SCS) indicates a new problem. C, Location of recording sites for the two monkeys M and P. The diagrams on the left represent the locations of penetrating sites to target LPFC (gray disks) and ACC (in black disks) in a common stereotaxic space. In the center, a histological section showing electrode tracks (indicated by arrows) targeting LPFC and ACC. On the right, MRI slice and 3D reconstruction for monkey P. Reconstruction of penetration sites are shown on the surface of the 3D volume.