Behavioral momentum and relapse of ethanol seeking: nondrug reinforcement in a context increases relative reinstatement.

Drug-related stimuli seem to contribute to the persistence of drug seeking and relapse. Behavioral momentum theory is a framework for understanding how the discriminative-stimulus context in which operant behavior occurs governs the persistence of that behavior. The theory suggests that both resistance to change and relapse are governed by the Pavlovian stimulus-reinforcer relation between a stimulus context and all sources of reinforcement obtained in that context. This experiment examined the role of the Pavlovian stimulus-reinforcer relation in reinstatement of ethanol seeking of rats by including added response-independent nondrug reinforcement in the self-administration context. Although rates of ethanol-maintained responding were lower in a context with added nondrug reinforcement than a context with ethanol alone, relative resistance to extinction and relative reinstatement were greater in the context previously associated with the nondrug reinforcer. Thus, both relative resistance to extinction and relative relapse of ethanol seeking depended on the Pavlovian stimulus-reinforcer relation between a context and all sources of reinforcement in that context. These findings suggest that to understand how drug-related contexts contribute to relapse, it may be necessary to consider not only the history of drug reinforcement in a context, but also the wide variety of other reinforcers obtained in such contexts.