The Emergence of Behavioral Pharmacology

Maintenance of drug-seeking behavior by a second-order schedule. Performances of squirrel monkeys under a second-order schedule in which the first 30-response FR completed after 5 min produces an intravenous injection of cocaine; the completion of each 30 responses also produces a brief visual stimulus (indicated by the many diagonal slashes on the three traces) that, following the 5-min FI, result in a brief stimulus plus administration of cocaine. The recording pen returns to baseline upon cocaine administration. Note that exceptionally high response rates were maintained under this second-order schedule. From (29) .