This project proposes to use electrophysiological and behavioral techniques such as brain wave measurements, single nerve cell recordings and stimulus discrimination behavior to better define the sites and mechanisms of action of phencyclidine and derivatives. A systematic evaluation of the role of behavioral and pharmacological factors in tolerance, physical dependence and withdrawal reaction to phencyclidine and possible methods of treatment will then be undertaken. The subjects of this research will be albino rats and Macaca mulatta monkeys.