Phasic transition from goal-directed to habitual control over drug-seeking produced by conflicting reinforcer expectancy.

Abstract

The transition from goal-directed to habitual control over drug-seeking has been experimentally demonstrated in animals, but there have been no comparable reports in humans. Following a recent animal design, the current study employed an outcome-devaluation procedure to test whether goal-directed control over tobacco seeking would be abolished by alcohol expectancy. Eighty smokers first learned that two responses earned tobacco or chocolate points, respectively, before tobacco was devalued by health warnings and smoking satiety. Participants were then presented with either a glass of beer/wine or water with instructions that this item could be consumed after the task (alternative reward). Then choice between the tobacco and chocolate response was measured in extinction to assess goal-directed control of tobacco seeking, in a nominal Pavlovian to instrumental transfer (PIT) test to assess stimulus control of tobacco seeking, and in a reacquisition test to assess the impact of direct feedback from the outcomes. The results showed that alcohol expectancy selectively abolished goal-directed control of tobacco seeking but not stimulus control or the impact of feedback from outcomes. These data suggest that 'endogenous' retrieval of low drug value governing goal-directed regulation of drug seeking is disrupted by conflicting appraisal of an alternative reinforcer, promoting habitual control, which may play a role in relapse.