ELECTRICAL STIMULATION OF MONKEYS PREFRONTAL CORTEX DURING DELAYED-RESPONSE PERFORMANCE

Trained 4 monkeys on an 8-sec delayed-response (DR) task. Stimulating electrodes were implanted in frontal cortex and head of caudate, contralateral to the responding hand, and ipsilateral prefrontal cortex was ablated. Stimulation at constant-current settings, of 4- or 2-sec duration, was applied during discrete portions of the DR trial. For stimulation across the principal sulcus DR performance remained at 90% criterion level for application during intertrial and early cue-presentation period. It dropped to 70-80% correct when applied during the final sec. of cue presentation, or last 4 sec. of delay, but dropped to chance level only when applied during the 1st few sec. of the delay. Differing results were obtained for stimulation of other prefrontal or caudate structures. Stimulation did not affect acquisition or retention of visual discriminations. (PsycINFO Database Record (c) 2006 APA, all rights reserved). © 1969 American Psychological Association.