Differences in Extinction of Cue-Maintained Conditioned Responses Associated with Self-Administration: Alcohol Versus a Nonalcoholic Reinforcer

Background: Stimuli paired with alcohol may evoke conditioned responses that influence consumption and relapse. Understanding extinction of conditioned responses for both alcohol and nonalcoholic reinforcers, and their relation to subsequent consumption, may be useful in identifying methods to maintain abstinence. Methods: Nine baboons self-administered alcohol (n = 4) or a nonalcoholic reinforcer (orange-flavored Tang^®, n = 5) under a 3-component chained schedule of reinforcement (CSR). Each component was associated with distinct stimuli and response requirements, which modeled periods of anticipation (Component 1), seeking (Component 2), and consumption (Component 3). No behavioral contingencies were in effect during Component 1. Responses in Component 2, required to gain access to Component 3, provided indices of seeking behavior. Alcohol or Tang® was available only in Component 3. Initial conditions parametrically manipulated the concentration of alcohol (2 to 6% w/v) or Tang (25 to 100%) that was available for self-administration. The breaking point (BP) of alcohol- and Tang-seeking responses at each of the concentrations was determined by adding a progressive ratio schedule to Component 2. Extinction of responding under stimulus conditions identical to those during baseline, but with no access to alcohol or Tang, was examined using across- and within-session extinction procedures. Results: The BP for 2% w/v alcohol was lower than that for 4 and 6%, which were closely similar. For Tang, BPs increased as the concentration increased. When concentrations of alcohol and Tang were adjusted to produce comparable BPs, self-administration of Tang was higher when compared to alcohol; however, alcohol-related cues maintained higher BPs than Tang-related cues when only water was available for self-administration. Alcohol seeking and self-administration responses were more resistant to extinction than those for Tang. Conclusions: Stimuli paired with alcohol or nonalcoholic reinforcers will gain different motivational properties. Alcohol-related stimuli produced persistent responding that was highly resistant to change, highlighting the role of environmental stimuli in compulsive drinking and relapse.