Renewal effect: context-dependent extinction of a cocaine- and a morphine-induced conditioned floor preference.

Rationale: Extinction of fear conditioning has been demonstrated to be context dependent. The experiments in this study evaluate whether extinction of a drug-cue association is also context dependent, using a conditioned floor preference procedure.

Methods: A drug (cocaine or morphine)-floor association was established in a specific context (black or white box). Rats were then given extinction training in which they were exposed to the floors in the conditioning context (Same) or in a different context (Diff) in the absence of the drug. In experiments 1 and 2, during drug-free extinction training, rats were confined to the drug-paired floor on 1 day and the saline-paired floor on the next day over extinction trials. In experiment 3, during drug-free extinction training, rats were given a choice between the drug-paired floor and the saline-paired floor over extinction trials. In all experiments, rats were then returned to the original conditioning context and tested for floor preference.

Result: Extinction of both the cocaine- and morphine-induced floor preference was greater when the rats received extinction training in the same context as conditioning than when they received extinction training in a different context.

Conclusion: Extinction of associations between external stimuli and the rewarding properties of a drug is context dependent, suggesting that extinction treatments would be most beneficial if conducted in the context in which the original association was established.