Neural markers of suppression in impaired binocular vision

Abstract

Objective/Purpose: 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. Design: A 5 ✕ 5 factorial repeated measures design was used, in which all participants completed a set of 25 conditions (stimuli of different contrasts shown to the left and right eyes). Participants: 25 individuals with a history of amblyopia, and 19 control participants with typical visual development, participated in the study. Methods: 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 4Hz. 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. Main outcome measures: The main outcome measures were the signal-to-noise ratio of the steady state visual evoked potential, and the fMRI β weights from a general linear model. Results: Neural responses generally 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. Conclusions: 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 e ects such as fever, skin ush, dysphoria, and glare. Moreover, both patching and penalization may destroy the binocular vision condition and damage the binocular vision function [9].…”

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.…”

Dissociable neural mechanisms of selective visual information processing underlie the effects of attention on visual appearance and response bias

“…The consistency in the response gain modulations observed across these studies, as well as in the present study, suggests that the response gain of the early sensory response is a common neural mechanism that mediates the effects of attention on perceptual performance and on the appearance of visual stimuli. Interestingly, reductions in response gain of early sensory responses have been shown to underlie sensory and attention deficits in clinical populations, such as schizophrenia, neurofibromatosis, and amblyopia [108][109][110][111][112] . Based on these results and our recent findings, it is possible that these patients perceive the world in a manner that is different from the healthy populations due to the reduced influence of attention on gain amplification of early sensory processing.…”