associated with impulsivity (51, 52), and in rodents, impulsivity predicts compulsive cocaine administration. In turn, overexpression of D2R in the striatum interferes with compulsive alcohol (53) and cocaine (54) intake. Imaging studies have also documented that in addicted subjects there is a decrease in DA release in the striatal regions (55) that is likely to further exacerbate an already low signaling from the reduced striatal D2R levels, which exert an inhibitory role on drug reward (56).
