dense cellular islands located within and near the ventral border of the striatum. Marker genes for one of these VS cluster subtype were highly enriched in the Islands of Calleja (ICjs). Cells from the other VS cluster subtype were restricted to Neurochemically Unique Domains in the Accumbens and Putamen (NUDAPs) (Figures 6 and 7).10,11 Within these subtypes, archetypal analysis revealed finer distinctions, including a TAC3-positive D1Sh-MSN that could represent the origin of a third pathway through cortico-basal ganglia loops (Figure 5).39 Together, these MSN subtypes and archetypes provide a blueprint for studying cell-type specific functions during sophisticated primate behaviors, and the cell-type-specific marker genes define potential molecular access points to enable the application of genetically coded tools in scientific or translational contexts.
