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. Author manuscript; available in PMC: 2018 Jan 1.
Published in final edited form as: Biol Psychiatry. 2016 Mar 31;81(1):31–42. doi: 10.1016/j.biopsych.2016.03.2104

Figure 3. Topography of dopamine release findings in schizophrenia compared to controls.

Figure 3

Schematic representations of DA release characteristics in the cortex (top), striatum (middle) and midbrain (bottom) in healthy controls (HC) and patients with schizophrenia (SZ) based on imaging findings in patients. DA neuron cell bodies, terminals and transmitters are depicted in red. Color gradients depict DA terminal densities. Cortex: The cortex receives sparse dopaminergic innervation that is poor in dopamine D2 receptors (D2) and transporter expression. This sculpts D2 displacement measurement, which is low in the cortex. In schizophrenia there is evidence for reduced cortical DA release. See text for details. Striatum: DA and cortical neuron terminals (green) are shown innervating medium spiny neuron spines (orange). Also shown are local cholinergic (blue) and GABAergic (brown) interneuron populations forming the striatal microcircuitry. There is considerable heterogeneity in DA release across striatal regions, e.g. dopaminergic innervation of ventral striatum (VST, also referred to as LST) is relatively sparse and is derived from dorsal tier cell groups that are poor in D2 and DAT. In contrast the sensorimotor striatum (SMST) receives dense dopaminergic inputs mostly from the ventral tier DA neurons that are rich in D2 and DAT. A greater number of synapse sites in the ventral striatum and high levels of D2 and DAT in SMST may account for high D2 displacement in these regions. Compared to VST and SMST, stimulant induced D2 displacement is low in the associative striatum (AST). In schizophrenia, DA release is increased across substriatal divisions due to a prominent increase in the AST. Midbrain: Shown are DA cell bodies, local GABAergic interneurons (brown) and D1 medium spiny neuron terminals (yellow). While there is heterogeneity in the level of expression of D2 receptors and DAT (e.g. dorsal tier and especially medial VTA neurons have low D2 and DAT levels), imaging studies showing subregional analysis of D2 displacement are lacking. However, in SZ there is a reduced stimulant-induced D2 displacement.