Single cell technologies that classify cell types according to their overall gene expression profiles provide powerful and quantitative methods for investigating cell type heterogeneity.12 Single cell and single nucleus RNA sequencing (scRNA-Seq and snRNA-Seq, respectively) have revealed new subtypes of MSNs and striatal interneurons.13-18 Moreover, these technologies are providing novel insights into cell-type-specific mechanisms for diseases involving the striatum, including drug addiction19 and Huntington’s disease.20 Despite these advances, we know neither the extent of MSN diversity in the primate striatum, nor how that diversity corresponds to the anatomical or neurochemical divisions of the highly articulated primate brain.
