occurs following administration of other addictive drugs, including morphine, nicotine, ethanol, and benzodiazepines, but not with non-addictive psychoactive substances such as fluoxetine or carbamazepine (Saal et al., 2003)2. Furthermore, prolonged self-administration of cocaine, unlike passive injections of cocaine or self-administration of food or sucrose, elicits an increase in the AMPAR/NMDAR ratio lasting 3 months (Chen et al., 2008). Cues predicting reward also caused this increase suggesting that this modification of excitatory synaptic function on VTA DA neurons has important roles in shaping behavioral adaptations (Stuber et al., 2008).
