Effects of intravenous cocaine on food maintained behavior in monkeys.

Two Macaca mulatta and one macaca java monkey were trained to press a key for food pellets on a differential reinforcement of low rate (DRL) schedule which required consecutive key-press responses to be spaced at least 20 sec apart in order to produce reinforcement. When behavior had stabilized, the monkeys were administered either 0.0,0.05,0.10,0.25, or 0.50 mg/kg of cocaine i.v. during daily sessions. Cocaine produced a bi-component, dose-dependent effect. Immediately following cocaine infusion there was a dose-related complete cessation of responding which began and ended abruptly. Following this postinfusion pause, a dose-related behavioral disruption in the form of shortened inter-response times was observed.