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. Author manuscript; available in PMC: 2013 Nov 25.
Published in final edited form as: Brain. 2003 Jun 4;126(0 8):10.1093/brain/awg184. doi: 10.1093/brain/awg184

Fig. 1.

Fig. 1

Schematic illustration of CST circuitry (Alexander et al., 1986). Each of five circuits originates with an efferent excitatory (glutamatergic) projection from one of several frontal cortical areas to caudate nucleus, putamen or ventral striatum. Direct or indirect routes connect these input nuclei of the basal ganglia to globus pallidus. From globus pallidus, there is an inhibitory (GABAergic) connection to thalamus; from thalamus, a glutamatergic projection returns to the cortical area that issued the original efferent projection to basal ganglia. DA = dopamine; GLU = glutamate; GL = glutamine; GABA = γ-aminobutyric acid; DLPFC = dorsolateral prefrontal cortex.