Send to

Choose Destination
Neuropsychopharmacology. 1999 Jun;20(6):542-55.

Effects of contingent and non-contingent cocaine on drug-seeking behavior measured using a second-order schedule of cocaine reinforcement in rats.

Author information

Department of Neuropharmacology, Scripps Research Institute, La Jolla, CA 92037, USA.


Rats were trained to respond with intravenous cocaine as the reinforcer under a fixed interval 15-min schedule, during which conditioned stimuli paired with cocaine were presented contingent on completion of a fixed ratio of 10 responses (i.e., second-order schedule of reinforcement). The effects of contingent and noncontingent cocaine were investigated. The results show that pretreatment with noncontingent (i.e., experimenter-administered) cocaine led to a satiation-like effect that was reflected in decreased numbers of responses and a tendency for an increased latency to initiate responding when the doses of cocaine administered were similar to or higher than the training/maintenance dose of cocaine. By contrast, noncontingent administration of cocaine doses lower than the training/maintenance dose, and response-contingent cocaine administration, led to increased drug-seeking behavior, as reflected in increased numbers of responses. The present data indicate that at least two factors determine whether administration of cocaine would lead to drug-seeking behavior: whether the cocaine administration is contingent or noncontingent, and the relative magnitude of the cocaine dose administered in relation to the training/maintenance dose of cocaine.

[Indexed for MEDLINE]
Free full text

Supplemental Content

Full text links

Icon for Nature Publishing Group
Loading ...
Support Center