Effect of Transcranial Direct and Alternating Current Stimulation on Visual Cortex Activity and Visual Quality

<ns3:p>Introduction: Transcranial direct current stimulation (tDCS) has shown potential in rehabilitating visual function among adults, including those with amblyopia. The effectiveness of various transcranial electrical stimulation (TES) protocols, particularly transcranial alternating current stimulation (tACS), remains underexplored.Objectives: The aim of this study is to compare the effects of α-tACS and anodal tDCS (a-tDCS) on visual cortex excitability in adults.Materials and methods: Twelve adults aged 22.41.32 years, with normal or corrected-to-normal vision, underwent three types of stimulation: a-tDCS, 10Hz α-tACS and placebo (SHAM), with one-week intervals. Stimulation was applied at 1.5 mA for 30 minutes. Assessments included high- and low-contrast visual acuity tests, contrast sensitivity tests, and visual evoked potentials (VEP), conducted pre- and post-stimulation.Results: Both α-tACS and a-tDCS significantly impacted visual cortex activity, enhancing contrast sensitivity and reducing VEP waveform latencies. Specifically, a-tDCS improved the amplitude of the late P2 component, indicating enhanced late-stage visual processing.Conclusions: This study confirms the efficacy of both a-tDCS and α-tACS in improving the sensitivity and processing speed of the visual cortex, suggesting their potential for visual rehabilitation.</ns3:p>