Single-cell sequencing of rodent ventral pallidum reveals diverse neuronal subtypes with non-canonical interregional continuity

The ventral pallidum (VP) was defined as a basal ganglia nucleus with dense input from ventral striatum. To further investigate a VP regional identity, we conducted a cross-species transcrip- tional characterization of VP cell types. We performed single nucleus RNA-sequencing of VP tissue from mice and rats and identified 16 VP neuronal subclasses with striking cross-species conservation. VP GABAergic neurons were surprisingly heterogeneous, consisting of 14 sub- classes from 3 developmental classes. Combining our sequencing data with a spatial atlas re- vealed that all VP subclasses extended beyond the traditional borders of VP. Integrating our VP data with prior sequencing data from striatal, hypothalamic, and extended amygdalar tissue con- firmed that cell types are shared among these regions. Due to the role of VP in feeding behavior, we also assessed the transcriptional impact of high-fat diet consumption, which induced altered expression of genes involved in oxidative phosphorylation and inhibitory signaling. Overall, our results demonstrate that VP is not a transcriptionally discrete nucleus; rather, VP contains cell types with diverse expression patterns that overlap with regions beyond the basal ganglia. ### Competing Interest Statement The authors have declared no competing interest.