Reinforcing brain stimulation and memory in monkeys

Abstract

Sixty electrodes were implanted in various structures in the brain of two cynomologous monkeys subsequently trained to perform a three-position delayed response task. Each brain point was tested for the effects of electric stimulation, applied during the retention interval, on delayed response performance and for appetitive and aversive effects. At all points where there was clear evidence of approach or avoidance with respect to the brain stimulus, there was definite impairment of delayed response performance. In six of the twenty cases where there was possible evidence of approach or avoidance, there was impairment of delayed response. In none of the twenty-six cases where there was no evidence of approach or avoidance was there any evidence of impairment. The data were interpreted as indicating that the impairment produced by brain shocks could be accounted for by their appetitive or aversive effects.