Mu and Beta Oscillatory Changes During a Motor Task Following Rehabilitation in Chronic MCA Stroke: Insights from EEG

BackgroundStroke in the middle cerebral artery (MCA) often leads to persistent upper limb disability. While clinical scales such as the Fugl-Meyer Assessment for the Upper Extremity (FM-UE) track motor recovery, high-density EEG provides insight into cortical motor-activation patterns. Event-related desynchronization/synchronization (ERD/ERS) in mu and beta bands may offer insight into recovery mechanisms.Objectivea) To characterize changes in mu and beta oscillations following upper limb rehabilitation in chronic MCA stroke patients, and b) To identify ERD features most closely associated with residual motor function.MethodsTen chronic MCA stroke patients and seven healthy controls underwent EEG during motor-imagery and active-movement tasks. Stroke patients received 15 sessions of rehabilitation over 8 weeks. EEG data were processed using EEGLAB/MATLAB and analyzed with ERD/ERS metrics. Spearman correlations with FM-UE scores were calculated.ResultsChronic stroke patients showed pathological ERS in ipsilesional beta rhythms that shifted toward ERD after rehabilitation, paralleling significant motor recovery. Although correlations did not reach significance, alpha oscillations in the ipsilesional hemisphere most closely related to functional gains.ConclusionOur findings suggest that rehabilitation in chronic stroke patients induces real cortical changes reflected in EEG oscillatory dynamics. Although preliminary, ipsilesional alpha and beta changes may represent biomarkers of genuine recovery, distinguishing neuroplastic improvement from compensatory mechanisms and guiding future therapeutic strategies.