Novel Insights into Lower Limb Corticomuscular Coupling Asymmetries: A Comparative Study of Stroke Patients and Healthy Controls.

While upper limb corticomuscular coupling (CMC) has been widely studied in stroke rehabilitation, lower limb CMC remains underexplored due to methodological challenges in accessing medial cortical areas. This study addresses this gap by innovatively investigating lower limb CMC during dynamic ankle dorsiflexion in stroke patients versus healthy controls. We recruited four healthy adults and four stroke patients capable of ankle dorsiflexion. We propose a novel paradigm integrating synchronized EEG-EMG recordings and normalized cross-spectral power (NCSP) analysis to quantify brain-muscle interactions across alpha, beta, and gamma bands. Results reveal a significant reduction in beta and gamma band coupling on the affected side of stroke patients compared to both healthy controls and their unaffected limbs, while unaffected limbs retained intact coupling. Crucially, our findings identify beta/gamma CMC attenuation as a potential biomarker for impaired motor control post-stroke, differing from prior upper limb studies that emphasized alpha-beta coherence. Additionally, we demonstrate lateralized NCSP asymmetry in healthy individuals, linking it to hemispheric dominance. These insights advance the understanding of frequency-specific corticomotor disruptions in lower limbs and provide a framework for targeted neuromodulation therapies to enhance recovery. This work establishes ankle dorsiflexion -based CMC analysis as a novel tool for precision rehabilitation in stroke.