Fig. 1: Task and recording sites.

a Sequence of frames indicates events in the spatial match-to-sample task. The animals were required to maintain center fixation throughout both active and passive task trials. At the end of active tasks trials, however, monkeys were required to make a saccade to a green target if the stimuli matched or to a blue target if the stimuli did not match. b Shape feature match-to-sample task, 8 possible shapes in a session shown in the inset. c Anatomical location of areas where recordings were made in the lateral prefrontal cortex. d Percentage of electrode sites for which all isolated neurons had significant selectivity for the location or shape of the stimulus (selective sites); for which some neurons had selectivity (partially selective); and for which no neurons had selectivity for stimuli (non-selective).