Effects of lesions of the medial forebrain on alternation behavior of rhesus monkeys.

In two experiments involving the delayed alternation task, monkeys with lesions of the hippocampal formation and monkeys with lesions of cingulate cortex were compared with controls. Either of these lesions caused impairment in original postoperative learning of delayed alternation; the hippocampal formation resections also produced a deficit in the retention of preoperatively acquired delayed alternation. The findings support the suggestion that these medial fore-brain areas are related to cerebral systems which include the anterior frontal cortex, and that these areas are necessary to more than "emotional" behavior.