Older adults reveal enhanced task-related beta power decreases during a force modulation task

Older adults (OA) compared to young adults (YA) reveal deteriorated fine motor control. However, it remains unknown whether this age difference is reflected on the central level, i.e., in electrophysiological correlates such as EEG task-related power (TRPow) in alpha (8-13 Hz) or beta band (13-30 Hz). Furthermore, we were interested in the association between age and alpha/beta power at rest as a potential determinant for TRPow changes. Twenty-five YA (19-29 years) and 45 OA (67-83 years) performed a force modulation (FM) task requiring to match a sinusoidal target force by exerting an isometric force with thumb and index finger. EEG was measured at rest and during FM task. YA outperformed OA in the FM task. For alpha, OA demonstrated less frontal power at rest than YA. For beta, OA revealed more power than YA in frontal, central, and parietal areas at rest. TRPow results depended on whether analyses were controlled for power at rest. When analyses were controlled, OA showed higher TRPow decreases than YA in beta in parietal and occipital areas during FM performance. TRPow decreases for beta were stronger in the contralateral than in the ipsilateral frontal hemisphere in OA than in YA. Decreases in TRPow indicate increased cortical activity to accomplish the FM task. Our findings suggest higher parietal and occipital processing demands while performing the FM task in OA than in YA. This study further confirmed the importance of controlling for EEG power at rest when investigating TRPow during motor performance to account for interindividual variability.