Theta burst stimulation in adults with symmetric and asymmetric visual acuity

Abstract

Purpose: Theta Burst Stimulation can in uence adult neuro-visual response in imbalanced visual pathways, possibly by in uencing cortical excitability. Our objective was to compare suppressive imbalance (SI) and visual acuity (VA) after applying repetitive Transcranial Magnetic Stimulation (TMS) between groups of subjects with normal binocular vision, visual asymmetry and amblyopia.Methods: Thirty -ve volunteers between 19 and 51 years of age, were split into three groups: 6 volunteers with asymmetric VA (group A); 19 amblyopes (group B); and 10 subjects with normal binocular vision (group C). VA and SI of all groups were evaluated before and after a single session of continuous theta-burst stimulation (cTBS) or placebo stimulation over the right occipital cortex.Results: In both groups A and B we found a signi cant VA improvement in the non-dominant eye after cTBS (p=0.04 and p=0.01, respectively). In SI evaluation, group A and group B also revealed a signi cant improvement after the cTBS session (p=0.03 and p=0.01, respectively).Finally, in the group of volunteers with normal binocular vision and for placebo groups A and B, there were no signi cant differences in VA and SI after cTBS.Conclusions: Amblyopic and visually asymmetric individuals improved VA and SI of the non-dominant eye after cTBS when compared to baseline and to placebo stimulation. These enhancements were not found in the group of volunteers with normal binocular vision. We can therefore reasonably assume that cTBS may interfere with the visual system of subjects that present some kind of asymmetry, possibly by improving neuronal imbalances.

Causal Role of the Frontal Eye Field in Attention-induced Ocular Dominance Plasticity

“…Hence, if stimulating the FEF simply influenced the binocular rivalry post-test by reducing the post-adaptation ODI, the ODI would then be further lowered along the y axis in Figure 5A, that is, the ocular dominance would become even more imbalanced after the stimulation. However, to our knowledge, TMS has been frequently found to rebalance both eyes rather than do the contrary (Clavagnier et al, 2013;Tuna et al, 2020;Tuna et al, 2022). Therefore, instead of abnormal measurement in the binocular rivalry post-test, we believe, the results of Experiment 2 more likely reflect a failure of ocular dominance shift towards the unattended eye due to a malfunction of FEF in adjusting ocular dominance during adaptation.…”

Negligible contribution of adaptation of ocular opponency neurons to the effect of short-term monocular deprivation

“…Besides monocular deprivation, recent work has developed new methods to investigate short-term ocular dominance plasticity ( Spiegel et al, 2013 ; Wang et al, 2021 ; Huang et al, 2022 ; Tuna et al, 2022 ; Song et al, 2023b ). Song and colleagues invented a “dichoptic-backward-movie” adaptation paradigm to study the ocular dominance shift induced by sustained eye-based attention.…”