# Properties and Mechanisms of Melanopsin Photoreception

> **NIH NIH R01** · BOSTON CHILDREN'S HOSPITAL · 2020 · $455,570

## Abstract

M1 ipRGCs are ocular neurons that sense light directly, using a G-protein coupled receptor called melanopsin,
and indirectly, through synaptic inputs from retinal circuitry. Unlike the classical rod and cone photoreceptors,
which use graded voltages to signal locally within the retina, these cells generate electrical spikes and send
them directly to over a dozen brain areas. Moreover, they are specialized for "non-image" visual functions such
as circadian regulation, hormonal control, and pupillary constriction. These functions respond to the overall
intensity of environmental illumination, or irradiance. Much remains unknown about how M1 ipRGCs sense
light for non-image vision. The overarching hypothesis of this proposal is that their intrinsic and synaptic
mechanisms are specialized for irradiance encoding—which benefits from slow and integrative responses—
even as they couple to the rapid events that generate spikes. We will identify M1 ipRGCs using techniques that
preserve their extrinsic and intrinsic drives, and employ a combination of electrophysiological, optical,
pharmacological, and molecular-genetic strategies that allow systematic and quantitative analysis in vitro. M1
ipRGCs are linked to several aspects of human health. For example, they are crucial regulators of the
circadian clock, whose dysregulation is implicated in mental illness, cancer, obesity, and other ailments.
Through a rigorous investigation of M1 ipRGC function, our research has the potential to reveal systems that
maintain health, are compromised in disease, and may be targeted for treatment.

## Key facts

- **NIH application ID:** 9999569
- **Project number:** 5R01EY023648-08
- **Recipient organization:** BOSTON CHILDREN'S HOSPITAL
- **Principal Investigator:** Michael Tri Hoang Do
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $455,570
- **Award type:** 5
- **Project period:** 2013-09-01 → 2023-07-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9999569

## Citation

> US National Institutes of Health, RePORTER application 9999569, Properties and Mechanisms of Melanopsin Photoreception (5R01EY023648-08). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9999569. Licensed CC0.

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