SUMMARY The striatum is the interface between dopamine reward signals and cortico-basal ganglia circuits that mediate diverse behavioral functions. Medium spiny neurons (MSNs) constitute the vast majority of striatal neurons and are traditionally classified as direct- or indirect-pathway neurons. However, that traditional model does not explain the anatomical and functional diversity of MSNs. Here, we defined molecularly distinct MSN types in the primate striatum, including (1) dorsal striatum MSN types associated with striosome and matrix compartments, (2) ventral striatum types associated with the nucleus accumbens shell and olfactory tubercle, and (3) an MSN-like type restricted to μ-opioid receptor rich islands in the ventral striatum. These results lay the foundation for achieving cell type-specific transgenesis in the primate striatum and provide a blueprint for investigating circuit-specific processing.

Transcriptional Diversity of Medium Spiny Neurons in the Primate Striatum