Figure 1.

Afferent regulation of the dopamine (DA) system. The DA system is under regulation by an inhibitory circuit including the basolateral amygdala (BLA)-ventral pallidum (VP) pathway that is activated by the infralimbic subregion (ilPFC), as well as an activating circuit. including the Re-ventral subiculum of the hippocampus (vSub)-nucleus accumbens (NAc)-VP pathway that is inhibited by the ilPFC. The result is that at baseline, about one-half of the VTA DA neurons are firing spontaneously. Only DA neurons that fire spontaneously can fire in response to rapid, phasic activation with bursts of action potentials, due to activation of pedunculopontine tegmental nucleus (PPTg) afferents.