The vascular supply of the functional compartments of the human striatum.

The basal ganglia (BG) contain several functional compartments and multiple, parallel segregated circuits processing different cortical information through cortical-BG-thalamus-cortical loops. Three zones of corticostriatal input are present: sensorimotor, associative and limbic, which correspond to poor, intermediate and strong calbindin (CB) labelling, respectively. Other functional compartments, such as striosomes, extrastriosomal matrix and matrisomes, also convey segregated projections. Microvascular territories in the human BG are spatially consistent with little overlap and few anastomoses. A high percentage of lacunar infarcts occur in the BG, yet the relationship between lacunae and functional compartments is unknown. We determined the relationship between microvascular territories and functional compartments within the human striatum. Microvascular territories were labelled by co-injection of diffusible dye, radio-opaque substance and gelatin into parental vessels and by sectioning each BG co-planar with the Talairach system. Sections underwent immunocytochemistry or histochemistry and the overlap of microvascular and functional territories was examined. CB staining of the arterial-injected striatum matched the functional compartments reported previously and overlay of microvascular territories revealed a correspondence between (i) the lateral lenticulostriate arteries (LSA) and sensorimotor zone; (ii) the medial LSA and associative zone; and (iii) the recurrent artery of Heubner (RAH) and limbic zone. A greater number of large vessels and capillaries were found in the matrix compared to striosomes, and a likely correspondence exists between high-density arteriole envelopes and matrisomes. The higher number of non-anastomotic vessels and capillary beds within the matrix predisposes these regions to both large lesions and small lacunar infarcts, creating specific symptoms based on striatal circuitry.