SOME PHYSICAL AND PHARMACOLOGICAL FACTORS AFFECTING DELAYED RESPONSE PERFORMANCE OF BABOONS FOLLOWING FRONTAL LOBOTOMY

Abstract

Two immature female Chacma baboons (Papio porcarius) trained in the delayed response situation, and then subjected to bilateral frontal lobotomy, showed a low level of performance in the delayed response situation for 6 mos. postoperatively under normal conditions (food intake approx. 350 calories/day, temp. approx. 80[degree]F). The following conditions significantly improved test performance: intramusc. injn. of Nembutal in approx. half the anesthetic dose; intramusc. injn. of 0.25-0.5 unit of insulin/kg. body wt.; reduction of the environmental temp. by 15[degree]-20[degree] for 3 hrs. before testing; fasting for 48-60 hrs. before testing. Benzedrine (5 mg.), elevation of the environmental temp. for 3 hrs. before testing, and prefeeding immediately before testing, resulted in a few chance trials or complete refusal to test. The relationship of these physical and pharmacological changes to energy metabolism is discussed: those alterations in conditions which temporarily increase food intake increase test scores; those which temporarily decrease food intake impair performance. The nature of the impairment in delayed response performance following frontal lesions is discussed. The physical changes and pharmacological agents used have previously been shown to affect central neural mechanisms. The significance of the relation between these mechanisms and frontal lesions and their behavioral implications are pointed out.