# Linking trigeminal and visual sensitivity in migraine

> **NIH NIH R21** · UNIVERSITY OF PENNSYLVANIA · 2022 · $446,875

## Abstract

Project Summary
Hypersensitivity is a canonical feature of migraine, with pain from light (photophobia) and touch (facial
allodynia) present during the ictal headache phase, and sometimes the inter-ictal period as well. Headache
and facial allodynia appear to reflect potentiation of trigeminal signals in migraine. This same mechanism may
account for photophobia as well. A subset of retinal ganglion cells express the photopigment melanopsin,
rendering them intrinsically photosensitive (the “ipRGCs”). Rodent studies show that these cells project to
thalamic and brainstem sites that also receive somatosensory input from the trigeminal nerve, providing a point
of neural interaction of somatic and visual signals. Can this promising biological model—derived in animal
studies—account for the properties of sensory symptoms in human migraine? To explore this question, we
require a quantitative hypothesis testing framework, and a reproducible, objective measure of trigeminal
sensitivity to supra-threshold stimuli. We propose to create this experimental platform and test key elements of
the trigeminal hypersensitivity model. We have modified a commercial “blink reflexometer” to measure
parameters of the corneal blink reflex to graded air-puff stimulation. We will test (Aim 1) if people with migraine
and inter-ictal photophobia, as compared to headache-free controls, have a systematic, group difference in the
slope of this reflexive sensitivity function or in a report of discomfort. Further, we will determine (Aim 2) if
graded variation in a simultaneous light stimulus interacts with air-puff intensity in the production of these
explicit and reflexive responses, thereby testing for anatomical convergence of visual and trigeminal somatic
signals.

## Key facts

- **NIH application ID:** 10578898
- **Project number:** 1R21NS130565-01
- **Recipient organization:** UNIVERSITY OF PENNSYLVANIA
- **Principal Investigator:** Geoffrey Karl Aguirre
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $446,875
- **Award type:** 1
- **Project period:** 2022-09-19 → 2025-08-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10578898

## Citation

> US National Institutes of Health, RePORTER application 10578898, Linking trigeminal and visual sensitivity in migraine (1R21NS130565-01). Retrieved via AI Analytics 2026-06-23 from https://api.ai-analytics.org/grant/nih/10578898. Licensed CC0.

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