Effects in Brain Symmetry and Functional Connectivity of tDCS Combined With XR in Chronic Stroke

This study examines the effects of combining transcranial direct current stimulation (tDCS) with extended reality (XR) exercises on brain connectivity and motor recovery in chronic stroke. We evaluate changes in electroencephalography (EEG) based connectivity and symmetry parameters, their correlation with clinical improvements, and their prognostic potential. Participants underwent XR rehabilitation with either active anodal tDCS or sham stimulation. EEG connectivity metrics and symmetry indices were assessed before and after the intervention alongside upper and lower limb motor function assessments. Correlation analyses were conducted to examine associations between EEG variations and motor improvements. As results, significant reductions in the brain symmetry index and the directional brain symmetry index were observed in the active tDCS group in the alpha, beta, and gamma EEG frequency bands, indicating an increase in symmetry after rehabilitation. Comparing the evolution of EEG features with clinical variations, in the active tDCS group greater correlations of changes in high frequency connectivity with upper and lower limb improvements were found. In conclusion, the addition of anodal tDCS to XR therapy seems to enhance neuroplasticity by modulating high-frequency power and connectivity, possibly also promoting more effective motor recovery. This study provides a comprehensive analysis of tDCS-enhanced XR rehabilitation, offering novel insights into brain connectivity changes and potential biomarkers for stroke recovery.