Roles of beta synchronization for motor skill acquisition change after stroke.

Beta event-related synchronization (ERS) following movement has been associated with motor skill acquisition in healthy individuals, yet its role in stroke recovery remains unclear. Given the prevalence of motor impairments after stroke, understanding how beta ERS relates to motor skill acquisition in this population is of significant clinical relevance, especially in view of emerging opportunities for neuromodulation. In this cohort study, we investigated whole-brain beta ERS during a feedback-guided motor skill acquisition task using magnetoencephalography (MEG) in 14 well-recovered stroke survivors in the chronic phase and 15 age-eligible healthy control participants. Motor ability was assessed with standardized clinical scales, and structural brain metrics were derived from magnetic resonance imaging. MEG data were projected into source space to enable comprehensive cluster-based analyses across the cortex. While stroke survivors exhibited significantly lower overall task performance, their capacity for motor skill acquisition did not significantly differ from that of control participants. In healthy participants, motor skill acquisition was strongly and positively associated with beta ERS in a cluster encompassing bilateral sensorimotor areas, which was absent in stroke survivors. Instead, stroke survivors showed a trend towards a negative association of motor skill acquisition with beta ERS. An exploratory analysis revealed that among various clinical and structural measures, only the Box and Block Test, a measure of gross manual dexterity, significantly moderated the association between beta ERS and motor skill acquisition. These findings suggest that although stroke survivors may retain the ability to acquire motor skills, the underlying neural mechanisms can be altered. In healthy adults with high manual dexterity, beta ERS appears to support short-term motor skill acquisition, whereas at lower dexterity levels, alternative mechanisms may compensate to sustain skill acquisition.