A Comparison of the Cellular and Molecular Atlases of the Macaque and Mouse Dorsal Horns

The spinal dorsal horn transforms incoming somatosensory information and transmits it supraspinally to generate modality-specific sensory percepts. Understanding precisely how neurons in this region process somatosensory information in rodents, and in higher-order species such as primates, has been hampered by the incomplete identification of individual cell types. In this study, we generate a comprehensive classification scheme for molecularly defined cell types across species-from mouse to primate by performing single nucleus RNA-sequencing of the Rhesus macaque dorsal horn and comparing it to a mouse meta-analysis. A comparison of the laminar distributions of these cell types across species lends further support to this classification. Despite the high conservation, we also identify species-specific differences in the expression of key genes. The study thus provides an essential resource for the functional interrogation of neural circuits underlying somatosensory processing within the dorsal horn and across species as well as for the validation of therapeutic targets.