Effect of Transcranial Direct Current Stimulation Targeting Brain Regions Identified Through Voxel-Based Morphometry...

Voxel-based morphometry (VBM) is a neuroimaging technique for quantitative analysis of brain structure. Previous studies have reported an association between gray matter (GM) volume in specific brain regions and balance function. Anodal transcranial direct current stimulation (tDCS) enhances excitability beneath the stimulation site and facilitates motor function. However, it remains unclear which brain regions are associated with one-legged standing (OLS) balance with eyes closed and whether anodal tDCS targeting these regions enhances this balance function. The present study aimed to (i) identify brain regions associated with OLS balance with eyes closed using VBM and (ii) test whether anodal tDCS applied to the identified region enhances this balance function.

The study consisted of two experiments. In Experiment 1, magnetic resonance imaging scans were performed in 66 healthy participants who underwent measurement of OLS balance time with eyes closed. In Experiment 2, brain regions identified through VBM analysis were stimulated with anodal tDCS, and the effect on OLS balance with eyes closed was evaluated. Thirty-two healthy participants were randomly assigned to the tDCS or sham group, and OLS duration with eyes closed was assessed before and after stimulation.

In Experiment 1, whole-brain analysis revealed that the cerebellar posterior vermis was associated with OLS balance with eyes closed. In Experiment 2, OLS duration with eyes closed was significantly increased poststimulation in the tDCS group after targeting the cerebellar vermis, including posterior vermis, while no significant difference was found between pre- and poststimulation in the sham group.

GM volume of the cerebellar posterior vermis is associated with OLS balance with eyes closed. Anodal tDCS targeting the cerebellar vermis, including the posterior vermis, enhances this balance function.