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

Comprehensive Summary

This study examines hybrid brain-computer interface (HBCI) systems and their use of electroencephalography (EEG) and electromyography (EMG). It aims to address the limited field knowledge of after-stroke corticomuscular coherence during ankle dorsiflexion and its relationship to motor function recovery. Synchronous EEG and HD-EMG recordings were taken from 13 patients who suffered from subacute strokes. These recordings were taken before and after a three-week rehabilitation, and 9 same-age healthy controls during isometric ankle dorsiflexion. Using multivariate coupling analysis, EEG and EMG projection vectors were used to identify optimal coupling patterns. Afterwards, CMC spectra and topographies were derived through coherence analysis to distinguish corticomuscular interactions on the spatial and spectral scales. Patients who had suffered from stroke showed reduced beta-band CMC patterns, particularly in the sensorimotor areas responsible for foot movement. No big differences in CMC patterns were seen between the stroke patients before and after rehabilitation. Further analysis showed a significant correlation between betaband CMC differences and clinical recovery, as measured by the Berg Balance Scale (BBS).

Outcomes and Implications

Beta-band CMC is a novel neurophysiological marker of motor function recovery in patients with stroke. The study findings give new information about the nuances of changes, post-stroke corticomuscular communications that have implications for the loss of motor functions. Beta-band CMC also gives evidence that will give direction for the design and application of BCI instruments that will revolve around the specific neurophysiological markers for therapies.