Figure 1

Schematic illustration of the DA pathways and circuitry that regulate dopamine (DA) release in the human brain. The DA-containing neurons in the ventral tegmental area (VTA)/substantia nigra (SN) project to the nucleus accumbens (mesolimbic pathway; orange), to the cortex (mesocortical pathway; yellow) and caudate putamen (nigrostriatal pathway; purple). DA neuron firing rates are maintained at tonic levels in part due to steady-state inhibitory firing from the ventral pallidum. Excitatory glutamatergic fibers (green) project from the prefrontal cortex, amygdala, and hippocampus, that synapse on striatal targets, including the nucleus accumbens (NAc). The NAc sends GABAergic projections (red) to the ventral pallidum that suppress ventral pallidum inhibition of the VTA, thereby facilitating phasic burst firing of ventral tegmental area DA neurons. Note: Placement of structures is only approximate. Amyg, amygdala; Caud, caudate; DA, dopamine; GABA, GABAergic projections; Glu, glutamatergic projections; Hipp, hippocampus; Put, putamen; VP, ventral pallidum. (Figure and legend adapted with permission from Treadway and Zald [19].)