The DS is divided into the caudate nucleus (Cd) and putamen (Pt) by the internal capsule. Spanning these structures are two neurochemical compartments, matrix and striosome, that form the ‘neostriatal mosaic.5,7 Broadly understood, matrix MSNs receive neocortical inputs from associative and sensorimotor cortex and give rise to the direct and indirect pathways.40 In contrast, striosomal MSNs, and the recently discovered, extrastriosomal ‘exo-patch’ MSNs,16,26 receive input from limbic territories, including the anterior cingulate cortex, orbitofrontal cortex, and anterior insular cortex,41 and project directly to midbrain dopamine neurons.42,43 Despite our advanced understanding of these circuit-based structures, we are only beginning to gain insights into the associated circuit-based functions. For example, striosomal MSN activations influence cognitive and emotional decision making44 and value based learning.45 A critical milestone that will enable us to accelerate functional discovery will be the development of cell-type- and compartment-specific viral vectors to enable circuit interrogation in NHPs. Here, we identified compartment-specific gene expression patterns for NHP matrix – STXBP6, GDA, and SEMA3E – and striosome – BACH2, KCNT1, KCNIP1, and KHDRBS3. Moreover, we found an extrastriosomal cell type, the
