The DS striosome and the VS are both implicated in limbic functions and reward processing, and thus it is interesting to compare these subpopulations. Our data indicate that there are many transcriptional similarities between the striosome and VS cell types, but also some key differences. For example, many striosome specific markers are upregulated in D1-NUDAP cells, including KCNIP1, KCNT1, KHDRBS3, and BACH2 (Figure S7C). Even PDYN, which is a widely acknowledged D1-striosome marker gene.50 is also expressed in D1-NUDAPs. On the other hand, D1-NUDAPs also express some genes which we found to be selectively expressed in the matrix, including STXBP6, GDA, and SEMA3E. OPRM1 was upregulated in the striosome, as predicted, but the upregulation was not as dramatic as we expected. In contrast, we observed robust OPRM1 signals in the NUDAPs (Figures7A-7C). Indeed, this selective enrichment of OPRM1 in the RXFP1-positive interface islands is a key piece of evidence in favor of the NUDAP hypothesis. This selective OPRM1 enrichment suggests the intriguing possibility that NUDAPs are part of the network of “hedonic hotspots?” Hedonic hotspots are regions in the NAc
