Figure 1.

Simplified sketch of the dopamine receptors (DR) connectome in the basal ganglia/striatum with a zoom (right circle) on signal transduction at presynaptic level in medium spiny neurons (MSN) dendritic boutons. Highlights on the elements associated with SCZ alterations are depicted in red. D1 positive medium spiny neurons of the direct pathway (MSNd) are in green, inhibitory D2 positive MSN of the indirect pathway (MSNi) are in red. Glutamatergic cortical input - presynaptic terminals are in magenta. DA “en passant” boutons are indicated in orange and in close proximity of glutamatergic postsynaptic spines. Cholinergic interneurons are in yellow. In the magnification on the right note the distribution of DR: D2s and D3 are presynaptic in DA terminals; D1/D3 postsynaptic in MSNd and D2L postsynaptic in MSNi. Other projections are in gray. Abbreviations: ACh, acetylcholine; DA, dopamine; Glu, glutamate; MSNd/i, direct/ indirect path projecting MSN neurons; GPi, internal segment of globus pallidus; SNr, substantia nigra, reticular part; STh, subthalamic nucleus; other common abbreviation and protein names as cited in text.