Neuron e

,pathologies such as substance use disorders (Redish, 2004) but have not yet been demonstrated in human studies of behav-ioral pathology. restricted our primary hypotheses to the ventral striatum. We hypothesized a group (DD patients compared to PD controls) by medication interaction effect during gain learning reflectingHere, we focused on compulsive disorders triggered in Parkin-son’s disease (PD) by dopamine agonists (DA) (Dagher and underlying susceptibility where DA would be associated with faster learning from gain outcomes along with greater ventralalternative options and negative costs. We used a model of rein-forcement learning to deconstruct the decision-making process underlying these compulsive behaviors. Reinforcement learning algorithms allow a computation of prediction error (d) in classical and instrumental conditioning, which acts as a teaching signal to update our predictions and influence our subsequent choices (Sutton and Barto, 1998). Converging animal and human studies