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Updated: May 30, 2026

Single-cell RNA-Seq of Defined Subsets of Retinal Ganglion Cells
Published on: May 22, 2017
Intrinsically photosensitive retinal ganglion cells: many subtypes, diverse functions
Tiffany M Schmidt1, Shih-Kuo Chen, Samer Hattar
1Department of Biology, Johns Hopkins University, Baltimore, MD 21218, USA. TMSchmidt@jhu.edu
Abstract:
For decades, rods and cones were thought to be the only photoreceptors in the mammalian retina. However, a population of atypical photoreceptive retinal ganglion cells (RGCs) expresses the photopigment melanopsin and is intrinsically photosensitive (ipRGCs). These ipRGCs are crucial for relaying light information from the retina to the brain to control circadian photoentrainment, pupillary light reflex, and sleep. ipRGCs were initially described as a uniform population involved solely in signaling irradiance for non-image forming functions. Recent work, however, has uncovered that ipRGCs are unexpectedly diverse at the molecular, cellular and functional levels, and could even be involved in image formation. This review summarizes our current understanding of the diversity of ipRGCs and their various roles in modulating behavior.
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