Plasma 17-Hydroxycorticosteroid Levels and Conditioned Behavior in the Rhesus Monkey

ALTHOUGH the effects of physical factors on the pituitary-adreno-cortical system have been extensively studied in the past two decades, the evaluation of the role of psychological factors in the regulation of ACTH secretion has been seriously hampered by the scarcity of techniques suitable for the systematic study of behavior in the individual experimental animal. Resent advances in animal conditioning methods within the field of experimental psychology, however, promise to provide a more refined approach to the investigation of such psychophysiological relationships. A relatively broad spectrum of behavioral patterns can now be operationally identified and experimentally manipulated. Specific aspects of the animal’s emotional reactions can be selectively and quantitatively evaluated against the background of stable behavioral baselines (e.g. 1, 2, 3). The present report describes a series of experiments with Rhesus monkeys in which operant conditioning techniques (4, 5) have been applied to the study of relationships between behavior and pituitary-adrenocortical activity, using plasma 17-hydroxycorticosteroid (17-OH-CS) levels as an index of ACTH secretion.