Habitual & goal-directed behavior in ethanol self-administering rats: Satiety-specific devaluation (2009)

Undergraduates: Douglas Glenn, none none none

Faculty Advisor: Donita Robinson
Department: Biology

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Alcohol abuse involves a transition from goal-directed to habitual patterns of alcohol consumption that are less sensitive to negative outcomes. Habitual and goal-directed behaviors can be studied in rats by using variable interval (VI) and fixed ratio (FR) training reinforcement schedules, respectively. This study used a satiety-specific devaluation procedure to reveal the motivational states engendered into behavior as a result of these training procedures. Male rats were trained to perform on either a VI30 or FR5 reinforcement schedule for 10% ethanol (10E) liquid reinforcer until responding was stabilized. Rats were tested in a satiety-specific devaluation for 10E: rats were allowed to drink 10E or a control liquid (2% maltodextrin) before separate extinction tests (no cues or reward). The effect of reward devaluation was measured by the number of lever presses the rats made during the 10-minute extinction sessions. After the control exposure, the FR5 group showed lever pressing that was significantly higher than the pressing after the 10E exposure. Conversely, in the VI30 group, lever presses were unchanged as a result of exposure. These results revealed that ethanol self-administering rats on a VI30 schedule exhibit habitual operant behavior, whereas rats on FR5 schedule exhibit goal-directed operant behavior. These data aid in our understanding of alcohol addiction by revealing how different learning paradigms can foster differentially motivated drug intake.