Beta-Band Cortico-Muscular Phase Coherence in Hemiparetic Stroke.

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Biomedical Engineering

Background:

• Stroke often damages corticospinal and corticobulbar pathways, leading to increased reliance on the opposite (contralesional) motor cortex for arm movement.
• Understanding these compensatory neural adaptations is crucial for developing effective post-stroke motor rehabilitation.

Purpose of the Study:

• To investigate the functional outcomes of contralesional cortical adaptation in post-stroke individuals during upper-limb tasks.
• To assess changes in neural pathways and nerve conduction delays using electroencephalography (EEG) and electromyography (EMG).

Main Methods:

• Utilized the Multi-Phase Locking Value (M-PLV) method to analyze beta-band phase coupling between motor cortex EEG and deltoid EMG signals.
• Collected EEG and EMG data from eight healthy controls and ten post-stroke participants during an upper-limb task.
• Estimated nerve conduction delay from the contralateral motor cortex to the deltoid muscle.

Main Results:

• Stroke participants exhibited significant alterations in ipsilateral (contralesional) EEG-EMG coherence compared to controls.
• Nerve conduction delays between motor cortices and the deltoid muscle were significantly higher in stroke survivors.
• Analysis revealed greater convergence of phase-coherence between ipsilateral and contralateral motor cortices in stroke participants.

Conclusions:

• M-PLV phase coherence analysis provides evidence of post-stroke contralesional motor adaptation, suggesting an increased role in paretic arm movement.
• The observed increased reliance on contralesional motor cortices may represent a maladaptive neural reorganization following stroke.
• These findings support the need for targeted rehabilitation interventions to address altered cortical control after stroke.