Projections of ipRGCs and conventional RGCs to retinorecipient brain nuclei

Retinal ganglion cells (RGCs), the output neurons of the retina, allow us to perceive our visual environment. RGCs respond to rod/cone input through the retinal circuitry, however, a small population of RGCs are in addition intrinsically photosensitive (ipRGCs) and project to unique targets in the brain to modulate a broad range of subconscious visual behaviors such as pupil constriction and circadian photoentrainment. Despite the discovery of ipRGCs nearly two decades ago, there is still little information about how or if conventional RGCs (non-ipRGCs) target ipRGC-recipient nuclei to influence subconscious visual behavior. Using a dual recombinase fluorescent reporter strategy, we showed that conventional RGCs innervate many subconscious ipRGC-recipient nuclei, apart from the suprachiasmatic nucleus. We revealed previously unrecognized stratification patterns of retinal innervation from ipRGCs and conventional RGCs in the ventral portion of the lateral geniculate nucleus. Further, we found that the percent innervation of ipRGCs and conventional RGCs across ipsi- and contralateral nuclei differ. Our data provide a blueprint to understand how conventional RGCs and ipRGCs innervate different brain regions to influence subconscious visual behaviors.

Automated summary

The study found that conventional RGCs and intrinsic photosensitive RGCs (ipRGCs) not only project to the suprachiasmatic nucleus but also play a role in many other subconscious ipRGC-recipient nuclei. The research revealed new stratification patterns of retinal innervation from ipRGCs and conventional RGCs in the lateral geniculate nucleus, and showed differences in the percentage of innervation across ipsi- and contralateral nuclei. These findings provide a blueprint for understanding how conventional RGCs and ipRGCs innervate different brain regions to influence subconscious visual behaviors.