Altered Sensorimotor Lateralization and Cross-modal Consistency in Stroke: A Simultaneous EEG-fNIRS Study

Area of Science:

• Neuroscience
• Rehabilitation Medicine
• Biomedical Engineering

Background:

• Stroke frequently causes motor deficits due to sensorimotor pathway disruption and altered cortical lateralization.
• Understanding neural reorganization post-stroke is crucial, but consistency between neural and hemodynamic levels remains unclear.

Purpose of the Study:

• To investigate cross-modal consistency between electroencephalography (EEG) and functional near-infrared spectroscopy (fNIRS) in stroke patients.
• To assess sensorimotor pathway reorganization and its correlation with motor impairment.

Main Methods:

• Simultaneous EEG and fNIRS recordings during unilateral handgrip tasks in stroke patients and healthy controls.
• Calculation of lateralization index (LI) from event-related desynchronization (ERD) and oxygenated hemoglobin (HbO) responses.
• Development of a cross-modal lateralization consistency index (cmLCI) to quantify EEG-fNIRS correspondence.

Main Results:

• Stroke patients showed altered hemodynamic responses (HbO) but no significant difference in neural LI compared to controls.
• Reduced event-related desynchronization (ERD) and LI in the beta band during affected-hand movement in stroke patients.
• Significantly reduced alpha and beta band cmLCI in stroke patients, particularly during affected-hand movement.
• Beta-band cmLCI positively correlated with Fugl-Meyer scores, indicating association with motor impairment.

Conclusions:

• Sensorimotor lateralization and its electrophysiological-hemodynamic consistency are altered after stroke.
• The proposed cmLCI effectively captures these alterations and correlates with clinical motor impairment.
• cmLCI shows potential as a multimodal indicator for assessing post-stroke cortical reorganization and motor deficits.