Figure 1.
Schematic illustration of dopamine projection pathways and circuitry regulating DA release in the human brain. DA firing rates are maintained at tonic levels in part due to steady-state inhibitory firing from the ventral pallidum. Excitatory projections from prefrontal cortex project, amygdala and hippocampus synapse on striatal targets, including the nucleus accumbens. The nucleus accumbens sends GABAergic projections to the ventral pallidum, suppressing VP inhibition of VTA, thereby facilitating phasic burst-firing of VTA DA neurons. Note: Placement of structure labels is approximate. Amyg = amygdala; Caud = Caudate; DA = Dopamine; GABA = GABAergic projections; Glu = glutamatergic projections; Hipp = hippocampus; NAcc = nucleus accumbens; Put = Putamen; SN = substantia nigra; VP = ventral pallidum; VTA = ventral tegmental area