Improved visual perception through visuomotor-coupled brain stimulation.

Non-invasive brain stimulation (NIBS) allows to investigate the causal relationship between the activity of a target brain region and the performance in a specific task. Regarding visual perception and NIBS of the visual cortex, previous attempts reported mixed results, possibly because different studies addressed similar questions but with different NIBS protocols have been used to address similar questions, and the influence of visuomotor activity on visual perception has not been considered. It is therefore still unclear whether the combination of visuomotor activity with which specific NIBS protocol can best influence visual perception. To fill this gap, we measured visual performance (detection) before and after three visuomotor-coupled, excitatory, high-definition NIBS [transcranial direct current stimulation (tDCS), oscilatory tDCS (otDCS), transcranial random noise stimulation (tRNS)] and a sham condition, all delivered to the visual cortex in the human brain. Eighty-four neurotypical participants divided in four groups (tDCS, otDCS, tRNS, Sham) took part in the study. The online visuomotor activity was a virtual reality game where participants had to hit different targets (mosquitoes), repeated for four days. Detection accuracy of visual stimuli was measured on each day. Results showed that otDCS was associated with significantly higher visual detection performance, compared to sham, tDCS, and tRNS, with effects emerging after the first session and becoming more pronounced across subsequent sessions. These effects depended on stimulus eccentricity, with the largest effects observed in the peripheral visual field. These findings suggest that visuomotor-coupled otDCS is a promising approach to enhance visual detection, particularly in the peripheral visual field.