The basal ganglia are highly conserved throughout vertebrate evolution,52 and a rough comparison of our results with single cell studies of the mouse striatum13-17 confirmed this pattern at the level of cell types. As with prior studies, we find a relatively even distributions of D1- and D2-MSN in the striatum. Approximately 10% of sampled MSNs were identified as striosome MSNs.17 We found that our neuronal nuclei samples contained approximately 85% MSNs and 15% interneurons; this is a higher proportion of interneurons than was recovered from single cell analysis of rodent striatum,17 but consistent with counts made in humans.53 A novel and relatively rare MSN type has been recently documented and variously described as eccentric SPNs,16,17 Pcdh8-MSNs,13 and D1H.15 Both D1/D2 hybrid and D1-NUDAP neurons shared some characteristics with this novel cell type. We formally compared our results to D1H because the sequencing depth was most similar between the studies. Co-clustering our data with the mouse data revealed that approximately half of the D1H population co-clustered with D1/D2-hybrids, and the other half co-clustered with D1-NUDAPs (Figures S3A-S3C). However, despite their similarities
