The GABAergic MSNs of the striatum are classified as D1 type or D2 type according to the dopamine receptor they express. A longstanding question concerns the diversity of these cell types, particularly relative to structural and functional features of the striatum. For example, dorsal MSNs initiate and control movements, whereas ventral MSNs are involved in motivation, reward, aversion, and similar behaviors. We found two D1-type MSNs (MSN1 and MSN4), one enriched in dorsal and one in ventral striatum, as well as two D2-type MSNs (MSN2 and MSN3), also dorsal and ventral, demonstrating a molecular distinction corresponding to the distinct circuits and functions of dorsal and ventral MSNs. In addition, we found putative patch-specific D1-/D2-type neurons (expressing Tshz1) and matrix-specific D2 neurons (expressing Gng2), consistent with staining patterns of these genes in the Allen Mouse Brain Atlas.
