Effects of a Cue Associated With Cocaine or Food Reinforcers on Extinction and Postextinction Return of Behavior

Studies of instrumental responding often include the delivery of a cue that is coincident with the delivery of the reinforcer. One purpose of this is for the cue to be removed during extinction and then presented later to assess whether responding returns (cue-induced reinstatement). In two experiments, we examined the effects of having a cue associated with reinforcement present or absent during extinction. In Experiment 1, the cue was associated with fixed ratio responding for intravenous cocaine or food pellets in one context (Context A), followed by extinction in another context (Context B), where responding produced the cue in one group but did not produce the cue in the other group. Afterward, contextual renewal was assessed with and without the cue in Context A. During extinction, a cue previously associated with cocaine reinforcement caused an increase in responding initially (an extinction burst) and throughout 16 2-hr extinction sessions, as well as weakened contextual renewal when animals were tested with the cue in Context A. In contrast, there were few detectable effects of the cue on extinction and contextual renewal when food pellets were the reinforcer. In Experiment 2, effects of a cue during extinction of progressive ratio responding were revealed with food pellets when animals showed weakened responding on the initial trials of postextinction reacquisition sessions. These experiments demonstrate that the presence of a cue associated with reinforcement during extinction may prolong responding in the short term while creating a more persistent form of extinction that resists relapse.