EFFECTS OF EPILEPTOGENIC LESIONS IN FRONTAL CORTEX ON LEARNING AND RETENTION IN MONKEYS

Abstract

Epileptoid discharges were induced in monkeys by implantation of alumina cream bilaterally over the frontal cortex. Monkeys which were trained on a delayed alternation task before implantation showed no appreciable deficit on successive retention tests for this task, given at intervals of 3 weeks over a period of 6 months. Other monkeys, which started training on the task after the onset of focal eeg spike discharges, were deficient in acquisition of the task[long dash]their rate of learning was approximately 1/4 the rate for normal monkeys. The epileptoid monkeys showed no impairment in learning a visual discrimination problem. It is concluded that focal epileptoid discharges interfere with the efficient learning, but not with the memory, of certain tasks. The deficit is restricted to tasks which are correlated with the cortical structures from which the discharges originate.