Fig. 1.

A model of the brain reward system. The nucleus accumbens (ventral striatum) is the major target of the mesolimbic dopaminergic system. It contains GABAergic medium spiny neurons (MSNs) that project to the ventral pallidum (VP). Natural rewards and addictive drugs increase the release of dopamine from the terminals of dopaminergic projections emanating from the ventral tegmental area (VTA). Nigrostriatal dopaminergic pathways (substantia nigra pars compacta to dorsal striatum) also participate in reward-related processes. DA dopamine, GABA g-aminobutyric acid, glu glutamate