Dynamic modulation of corticomuscular coherence during ankle dorsiflexion after stroke: towards hybrid BCI for lower-limb rehabilitation

Comprehensive Summary

This study investigated how corticomuscular coherence (CMC)—the functional coupling between cortical EEG activity and muscle EMG—changes during ankle dorsiflexion in subacute stroke patients and how these changes relate to motor recovery. Using synchronous EEG and high-density EMG recordings and a multivariate coupling method (ssPLSC), the authors compared 13 stroke patients (before and after three weeks of rehabilitation) with 9 healthy controls. Stroke patients exhibited significantly reduced CMC, particularly in the beta band (14–30 Hz), with altered spatial patterns over sensorimotor regions controlling the foot. Although overall CMC did not significantly increase after rehabilitation, changes in beta-band CMC were positively correlated with improvements in balance performance measured by the Berg Balance Scale. These findings identify beta-band CMC as a physiologically meaningful marker of disrupted corticomuscular communication after stroke and highlight its relevance for monitoring and guiding lower-limb rehabilitation, especially within hybrid brain–computer interface (BCI) frameworks.

Outcomes and Implications

Clinically, this work suggests that beta-band corticomuscular coherence can serve as a neurophysiological biomarker of lower-limb motor control and balance recovery after stroke. The demonstrated link between beta-band CMC modulation and balance improvement supports the use of CMC-driven feedback as a target for hybrid EEG–EMG BCI rehabilitation systems. Such systems could move beyond accuracy-based control and instead promote adaptive neuroplasticity by selectively reinforcing recovery-relevant corticospinal communication. In practice, this approach may enable more personalized, mechanism-based neurorehabilitation strategies for gait and balance deficits, potentially improving functional outcomes and reducing long-term disability in stroke survivors.