# Interocular Suppression and Selective Attention in Amblyopia

> **NIH NIH R01** · SMITH-KETTLEWELL EYE RESEARCH INSTITUTE · 2024 · $35,000

## Abstract

Project Summary
Long-term and chronic visual suppression to the visual input from the non-preferred eye is a key factor in
developing amblyopia, or “lazy eye”, as well as a critical barrier to treat amblyopia. Amblyopia is commonly
caused by misalignment of the eyes (strabismus), chronic optical blur in one eye due to unequal refractive
errors in two eyes (anisometropia), or a mixture of strabismus and anisometropia during early childhood,
affecting about 3% to 5% of the population worldwide. Our long-term goal is to understand how and where
suppression occurs in the brain. We propose that selective visual attention plays a role in visual suppression.
Our hypothesis in the current proposal is that selective visual attention biases competition between eyes and
modulates interocular suppression by selectively facilitating responses from the preferred eye and suppressing
responses from the non-preferred eye along the visual cortical hierarchy. To test our hypothesis, we will use
psychophysics to measure whether valid cueing of the stimulus in the amblyopic eye reduces suppression under
dichoptic viewing in adults with amblyopia, compared with invalid/neutral cueing (Aim 1). In Aim 2, we will
use frequency-tagged EEG source imaging along with a behavioral measure of perceptual eye dominance to
compare the effects of selective attention and increasing contrast to the amblyopic eye on perception and
neural responses of each eye during binocular rivalry. We will simultaneously measure and compare the neural
activities along the cortical hierarchy of both eyes under the states of visual perceptual dominance and
suppression in adults with amblyopia and normal vision. These measures will help determine: 1) how and
where the brain suppresses visually conflicting images in amblyopia; 2) how an increase in bottom-up visual
salience by increasing the contrast input to the amblyopic eye changes the neural representation of the
amblyopic eye signal and 3) whether paying attention to the amblyopic eye has a similar effect on neural
activity as increasing contrast to the amblyopic eye. In Aim 3, we will use frequency-tagged EEG source
imaging coupled with visual psychophysics to measure cortical activity and behavioral performance during a
multiple-object tracking task with moving targets presented to one eye and moving distractors presented to the
other eye. This aim will comprehensively characterize: 1) whether visual attention modulates interocular
suppression by selectively facilitating neural responses from the preferred eye and suppressing responses from
the non-preferred eye along the visual cortical hierarchy (Aim 3a); 2) whether there are differences in
attentional modulation between normal and amblyopic vision, in terms of temporal dynamics (Aim 3b) and
attentional resource availability determined by the number of targets to be tracked (Aim 3c). The proposed
studies will systematically investigate visual perception and neural correlates underlying intero...

## Key facts

- **NIH application ID:** 10976960
- **Project number:** 3R01EY035346-02S1
- **Recipient organization:** SMITH-KETTLEWELL EYE RESEARCH INSTITUTE
- **Principal Investigator:** Chuan Hou
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $35,000
- **Award type:** 3
- **Project period:** 2023-08-01 → 2027-02-28

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10976960

## Citation

> US National Institutes of Health, RePORTER application 10976960, Interocular Suppression and Selective Attention in Amblyopia (3R01EY035346-02S1). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10976960. Licensed CC0.

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