Age-Related Electrophysiological Reorganization During In-Phase and Anti-Phase Bimanual Coordination

Background/Objectives: Healthy aging is associated with declines in bimanual coordination, particularly under more demanding coordination modes. However, the electrophysiological changes accompanying these behavioral differences and their relevance to performance remain unclear. This study examined age-group differences in behavioral performance, ERP responses, and beta-band dynamics during in-phase and anti-phase bimanual coordination. Methods: Forty-two right-handed adults were included in the primary analyses of a bimanual coordination task in both in-phase and anti-phase coordination modes. Behavioral outcomes included accuracy, reaction time, and inverse efficiency scores. EEG measures included P1, N1, and P3 responses, prestimulus beta power, fixed-window relative beta power, baseline-adjusted absolute beta power, and individualized cumulative event-related desynchronization burden. Results: The older group was slower and less efficient overall, with disproportionate accuracy and efficiency costs during anti-phase coordination. Electrophysiologically, aging was associated with larger early P1 responses, a sensor-level redistribution of P3 amplitude and latency, and higher prestimulus beta activity. Fixed-window relative beta and baseline-adjusted absolute beta showed age-group differences without corrected coordination effects, whereas individualized cumulative ERD burden showed age-group, coordination, and interaction effects. Conclusions: Healthy aging was associated with poorer discrete bimanual coordination performance, altered early visual and late positive ERP responses, and stronger cumulative beta suppression under demanding anti-phase coordination.