Dynamic central-peripheral balance in brain-muscle interactions reveals motor impairment in post-stroke hemiplegia:...

Hemiplegia following stroke is characterized by disrupted neuromuscular interactions, yet the central-peripheral dynamics remain unclear. This study investigated dynamic causal interactions between electroencephalography (EEG) and electromyography (EMG) using the adaptive directed transfer function (ADTF) during a thumb-pressing task in hemiplegic patients and explored the central-peripheral balance between central motor commands and peripheral sensory feedback. Results suggested that patients with better motor functions may exhibit a dynamic transition from relatively balanced bidirectional interactions to centrally dominated descending control and back to balance. Patients with more severe hemiplegia exhibited pronounced descending control impairment and ascending feedback enhancement, particularly on the affected side. The difference between the out-degrees of central-peripheral pathways during the motor preparatory phase served as a potential predictor of motor function, as assessed by the Barthel Index. This finding provides exploratory evidence for the imbalance between peripheral-to-central and central-to-peripheral coupling as a potential neural biomarker for functional recovery, tentatively supporting the development of more targeted and personalized rehabilitation strategies.