We conclude that 1) eSPNs represent a third axis of SPN diversity, distinct from the dSPN/iSPN and patch/matrix distinctions; 2) eSPNs harbor rare, additional molecular diversity; and 3) by using markers thought to exclusively distinguish iSPNs from dSPNs, functional studies have lumped eSPNs in with canonical SPNs. These results highlight the utility of unbiased, high-throughput single-cell methods for defining neuronal populations.
