A High-Resolution Transcriptomic Atlas of Cell Types in the Ventral Visual Thalamus

Axons from retinal ganglion cells (RGCs) convey visual information from the retina to distinct regions within the mammalian brain, including several nuclei within the visual thalamus. In rodents, the visual thalamus contains three primary retinorecipient regions: the dorsal lateral geniculate nucleus (dLGN), the ventral LGN (vLGN), and the intergeniculate leaflet (IGL). While principal retinorecipient neurons in dLGN are excitatory thalamocortical relay cells (TRCs), most neurons in vLGN are GABAergic, including GABAergic projection neurons. Previous studies suggest that both dLGN and vLGN neurons may be specified into parallel visual pathways for processing and transmitting to select cortical and subcortical brain regions, respectively. While dLGN neurons have been studied extensively, prior studies suggest that additional cell types remain to be identified and characterized in vLGN. Here, we used transcriptomic profiling to generate the first comprehensive and high-resolution atlas for cell types in the mouse vLGN. This atlas was generated based on a single nucleus-sequencing (snRNA-Seq) dataset that contained data from over 16 500 nuclei. We systematically analyzed neuronal and non-neuronal cell types across vLGN based on gene expression. The results revealed the identity of 20 potential types of neurons in the mouse vLGN, including at least two excitatory neuronal types. This comprehensive transcriptomic atlas of mouse vLGN establishes a benchmark reference atlas and a foundational resource for deep and integrative investigations of cell type and circuit function, development, and evolution of an essential nucleus of the mammalian visual system.