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Direct-Coupled Electroretinogram (DC-ERG) for Recording the Light-Evoked Electrical Responses of the Mouse Retinal Pigment Epithelium
Published on: July 14, 2020
Photoentrainment and pupillary light reflex are mediated by distinct populations of ipRGCs
S-K Chen1, T C Badea, S Hattar
1Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Abstract:
Intrinsically photosensitive retinal ganglion cells (ipRGCs) express the photopigment melanopsin and regulate a wide array of light-dependent physiological processes. Genetic ablation of ipRGCs eliminates circadian photoentrainment and severely disrupts the pupillary light reflex (PLR). Here we show that ipRGCs consist of distinct subpopulations that differentially express the Brn3b transcription factor, and can be functionally distinguished. Brn3b-negative M1 ipRGCs innervate the suprachiasmatic nucleus (SCN) of the hypothalamus, whereas Brn3b-positive ipRGCs innervate all other known brain targets, including the olivary pretectal nucleus. Consistent with these innervation patterns, selective ablation of Brn3b-positive ipRGCs severely disrupts the PLR, but does not impair circadian photoentrainment. Thus, we find that molecularly distinct subpopulations of M1 ipRGCs, which are morphologically and electrophysiologically similar, innervate different brain regions to execute specific light-induced functions.
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