# Melanopsin Activation and Human Visual Electrophysiological Responses

> **NIH NIH R21** · UNIVERSITY OF ILLINOIS AT CHICAGO · 2020 · $193,137

## Abstract

PROJECT SUMMARY
The recently discovered intrinsic photosensitive retinal ganglion cells (ipRGCs), which express melanopsin
photopigment, are a third class of photoreceptors in mammalian retina other than rods and cones. Research
thus far has shown that ipRGCs play a very important role for a number of sub-conscious non-image-forming
functions, such as circadian photoentrainment, the pupil light reflex, sleep and mood regulation. Nevertheless,
it is unclear whether melanopsin activation in ipRGCs contribute to visual processing. IpRGCs provide
feedback to dopaminergic amacrine cells to restructure retinal processing and also send direct signals to the
lateral geniculate nucleus (LGN) in the thalamo-cortical visual pathways. Therefore, melanopsin activation in
ipRGCs may alter visual processing. However, how melanopsin affects visual processing, particularly in
humans, is unclear. The proposed research will use a lab-made device that allows independent control of
melanopsin, rod and cone stimulations to investigate how different melanopsin activation levels in ipRGCs
affect physiological responses in the visual pathways. We will record flicker and pattern Electroretinogram
(ERG) and Visual Evoked Potential (VEP) simultaneously to assess whether melanopsin’s effects are
mediated by intraretinal signaling, ipRGC-to-LGN projection or both. The physiological results will be correlated
with psychophysical measurements under the same conditions. Our project will help to advance our
understanding of the mechanisms for melanopsin activation to affect visual processing.

## Key facts

- **NIH application ID:** 9986756
- **Project number:** 5R21EY029488-02
- **Recipient organization:** UNIVERSITY OF ILLINOIS AT CHICAGO
- **Principal Investigator:** Dingcai Cao
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $193,137
- **Award type:** 5
- **Project period:** 2019-08-01 → 2022-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9986756

## Citation

> US National Institutes of Health, RePORTER application 9986756, Melanopsin Activation and Human Visual Electrophysiological Responses (5R21EY029488-02). Retrieved via AI Analytics 2026-05-21 from https://api.ai-analytics.org/grant/nih/9986756. Licensed CC0.

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