Single-Cell Transcriptomic Analysis of Macaque LGN Neurons Reveals Novel Subpopulations

Neurons in the lateral geniculate nucleus (LGN) provide a pivotal role in the visual system by modulating and relaying signals from the retina to the visual cortex. Although the primate LGN, with its distinct divisions (magnocellular, M; parvocellular, P; and koniocellular, K), has been extensively characterized, the intrinsic heterogeneity of LGN neurons has remained unexplained. With the development of high-throughput single-cell transcriptomics, researchers can rapidly isolate and profile large sets of neuronal nuclei, revealing a surprising diversity of genetic expression within the nervous system, such as two types of K neurons (as reported by Bakken et al., eLife, 10, e64875, 2021). Here, we analyzed the transcriptomes of individual cells belonging to macaque LGN using raw data from a public database to explore the heterogeneity of LGN neurons. Using statistical analyses, we found additional subpopulations within the LGN transcriptomic population, whose gene expressions imply functional differences. Our results suggest the existence of a more nuanced complexity in LGN processing beyond the classic view of the three cell types and highlight a need to combine transcriptomic and functional assessments. A complete account of the cell type diversity of the primate LGN is critical to understanding how vision works.