Fig. 1.

A: schematic diagram of the monkey brain, outlining areas where recordings were performed. Recordings in dorsolateral prefrontal cortex (dlPFC) sampled areas 8a and 46. Recordings in posterior parietal cortex (PPC) sampled areas 7a and the lateral intraparietal area (LIP). AS, arcuate sulcus; PS, principal sulcus; IPS, intraparietal sulcus; STS, superior temporal sulcus. B: remember-first task. The white fixation point instructed the monkeys to remember the first stimulus (which could appear at 1 of 8 locations arranged on a ring of 12° eccentricity). The monkeys were required to ignore the second stimulus, which appeared after an intervening delay period. After a second delay period, the fixation point turned off cuing the monkey to saccade to location of the first stimulus. C: remember-second task. A blue fixation point instructed the monkey to remember and saccade to the location of the second stimulus. In an initial set of experiments, the second stimulus appeared always diametric to the first (diametric distractor set), for both the remember-first and remember-second tasks. In a second series of recordings, the second stimulus appeared at a randomized location relative to the first stimulus (randomized distractor set). D: oculomotor delayed response (ODR) task. In this task, only one stimulus was presented, and after a delay period the monkey was required to saccade to its remembered location.