The Role of Dopamine in the Dorsal Striatum and Its Contribution to the Reversal of Habit-Like Ethanol Seeking

Inflexible, habitual drug seeking despite negative consequences is a key component of alcoholism. Habitual behavior requires the dorsolateral striatum (DLS) in rodents, while flexible behavior requires the dorsomedial striatum (DMS). Lesion of dopamine inputs to the DLS can prevent habit formation; however, the role of dopamine to reverse an existing alcohol-seeking habit is unknown. Therefore, we tested the hypothesis that blocking dopamine in the DLS may initiate a reversion from habitual to flexible behavior in which the DMS predominates. Rats were trained to self-administer sweet solutions (S) or sweetened ethanol solutions (S/E) until they expressed habit-like seeking. Electrodes were surgically implanted in the DMS to measure neuronal activity. Behavioral flexibility was then assessed using a contingency degradation procedure with and without bilateral DLS infusions of the non-specific dopamine receptor antagonist α-flupenthixol (FLU). Following contingency degradation, both S and S/E rats showed a reduction in reinforcer seeking after FLU administration but not saline. Preliminary results showed a decrease in DMS neuronal firing rate over the course of the first degradation session for both S/E and S rats. Our results suggest that a reduction in DLS dopamine facilitates reversal of habitual reward seeking, and changes in DMS neuronal activity may precede the resurgence of flexible behavior.Bachelor of Scienc