Relatively ancient brain regions mediate the basic, survival-dependent activities of desiring, seeking out, locating, and enjoying natural rewards such as food, novelty, and social stimuli. These reward systems are also activated by alcohol and other drugs used for their rewarding effects, perhaps abnormally so, with repeated exposures to such “supranormal” drug stimuli contributing to the development of drug dependence. A core element of such reward-related neurocircuitry has long been attributed to the nucleus accumbens (NAc) and the dopamine (DA) input it receives from DA cell bodies in the ventral tegmental area (VTA) of the midbrain. Additional critical components of the reward circuitry include other forebrain targets of DA projections from VTA, including the amygdala, hippocampus, and prefrontal cortex (PFC), along with the dorsal striatum and the input it receives from DA cell bodies in the midbrain substantia nigra (SN) (i.e., the nigra-striatal DA system), with these mesolimbic and mesocortical brain regions closely interconnected (e.g., see Berridge, 2004).
