ABSTRACT
The latency estimation of cortico-muscular coherence (CMCoh) could provide valuable information, especially for the pathological study. However, the conduction time from the central cortical rhythm to peripheral oscillations has not been explored for stroke patients. In this study one recently proposed method, maximizing coherence, was applied into the coherence analysis to estimate the latency by which the extensor carpi radialis electromyographic signals lagged behind the electroencephalographic time series with seven subcortical stroke subjects. Significantly prolonged conduction time was found in affected sides compared with the unaffected sides. The interhemispheric spatial displacement was also calculated using electrodes projection optimization and spherical surface laplacian. The results showed that the CMCoh could help investigate the cerebral reorganization after stroke.
Subject(s)
Motor Cortex/physiopathology , Muscle Contraction , Muscle, Skeletal/physiopathology , Neural Conduction , Neuronal Plasticity , Paresis/physiopathology , Stroke/physiopathology , Adult , Female , Humans , Male , Middle Aged , Stroke/complications , Young AdultABSTRACT
Whether afferent feedback contributes to the generation of cortico-muscular coherence (CMCoh) remains an open question. In the present study, a multivariate autoregressive (MVAR) model and partial directed coherence (PDC) were applied to investigate the causal influences between the central rhythm and electromyographic (EMG) signals in the process of CMCoh. The system modeling included activities from the contralateral and ipsilateral primary sensorimotor cortex (M1/S1), supplementary motor area (SMA) and the time series from extensor carpi radialis (ECR) muscles. The results showed that afferent sensory feedback could also play an important role for the generation of CMCoh. Meanwhile, significant coherence between the EMG signals and the activities in the SMA was found in two subjects out of five. Connectivity analysis revealed a significant descending information flow which possibly reflected direct recruitment on the motoneurons from the SMA to facilitate motor control.
