Great apes and rhesus monkeys as subjects for psychopharmacological studies of stimulants and depressants.

A group of experiments is described in which chimpanzees and orangutans are utilized as subjects in research projects designed to evaluate the effects of stimulant and depressant drugs on learning and performance. Efficiency of performance on a task which measures spaced responding was impaired when subjects smoked cigarettes containing delta9-tetrahydrocannabinol prior to testing. In a sequential learning task, these subjects also demonstrated reduced performance when stimulatn drugs were orally administered before testing. Depressant drugs did not produce comparable decrements in sequential learning performance. Physical and behavioral tolerance and dependence on ethanol were investigated in rhesus monkey subjects using a variety of experimental procedures, including forced oral acceptance, intragastric intubation, intravenous infusion, and conditioned voluntary oral acceptance.