Neural markers of suppression in impaired binocular vision

Abstract

Even after conventional patching treatment, individuals with a history of amblyopia typically lack good stereo vision. This is often attributed to atypical suppression between the eyes, yet the specific mechanism is still unclear. Guided by computational models of binocular vision, we tested explicit predictions about how neural responses to contrast might differ in individuals with impaired binocular vision. Participants with a history of amblyopia ( N = 25), and control participants with typical visual development ( N = 19) took part in the study. Neural responses to different combinations of contrast in the left and right eyes, were measured using both electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Stimuli were sinusoidal gratings with a spatial frequency of 3c/deg, flickering at 4 Hz. In the fMRI experiment, we also ran population receptive field and retinotopic mapping sequences, and a phase-encoded localiser stimulus, to identify voxels in primary visual cortex (V1) sensitive to the main stimulus. Neural responses in both modalities increased monotonically with stimulus contrast. When measured with EEG, responses were attenuated in the weaker eye, consistent with a fixed tonic suppression of that eye. When measured with fMRI, a low contrast stimulus in the weaker eye substantially reduced the response to a high contrast stimulus in the stronger eye. This effect was stronger than when the stimulus-eye pairings were reversed, consistent with unbalanced dynamic suppression between the eyes. Measuring neural responses using different methods leads to different conclusions about visual differences in individuals with impaired binocular vision. Both of the atypical suppression effects may relate to binocular perceptual deficits, e.g. in stereopsis, and we anticipate that these measures could be informative for monitoring the progress of treatments aimed at recovering binocular vision.

The Study of Short-Term Plastic Visual Perceptual Training Based on Virtual and Augmented Reality Technology in Amblyopia

“…However, atropine may have some side effects such as fever, skin flush, dysphoria, and glare. Moreover, both patching and penalization may destroy the binocular vision condition and damage the binocular vision function [ 9 ].…”

Amblyopic deficits in monocular processing and binocular interactions revealed by submillimeter 7T fMRI and EEG frequency tagging

“…Stronger than normal binocular suppression of neuronal activity has also been observed in the early visual cortex of strabismic monkeys (Bi et al, 2011), in which the suppression from FE to AE was stronger than from AE to FE (Shooner et al, 2017). However, there has been no clear evidence for abnormal binocular intergration or imbalanced suppression in the very few neuroimaging studies in human amblyopia (Baker et al, 2015; Chadnova et al, 2017; Farivar et al, 2011; Lygo et al, 2021).…”

“…In addition to monocular deficits, clinical and psychophysical studies also suggest abnormalities in binocular suppressions (Hess et al, 2014; Zhou et al, 2018), consistent with electrophysiological evidence in animal models (Bi et al, 2011; Shooner et al, 2017). However, functional abnormalities in binocular interactions remain highly controversial in neuroimaging studies of human amblyopia (Baker et al, 2015; Chadnova et al, 2017; Farivar et al, 2011; Lygo et al, 2021).…”

Evaluation of the Efficacy of a New Dichoptic Digital Platform to Treat the Anisometropic and Isometropic Amblyopia

“…This training is able to generate some neural changes, such as an evolution to a non-effort pattern of the neural activity in the frontal, parietal, and occipital lobes [ 26 ]. These changes allow overcoming some of the alterations leading to interocular suppression and consequently to a less developed visual function in the amblyopic eye [ 27 , 28 , 29 , 30 ]. Li et al [ 29 ] demonstrated that interocular suppression plays a key role in the visual deficits associated with anisometropic amblyopia.…”