Study On Cross-frequency Coupling Charactoristics Of EEG And EMG In Stroke Recovery

Cross frequency coupling(CFC),as a phenomenon that can reflect the information interaction and transmission beetween the brain and muscles across different oscillations in neuromuscular system,is helpful to understand the mechanism of motor control and its dyskinesis,and provides a new perspective for the evaluation of stroke rehabilitation.The coupling state of different rhythms in brain has been proved to be closely related to the cognitive and memory activities.CFC has obvious advantages in describing the characteristics from the perspective of the interaction between different rhythms of EEG signals.In this paper,the analysis methods of characteristics at different aspects of CFC were studied from the perspective of nonlinear analysis of motor control system,and used to evaluate the rehabilitation status of stroke patients.In this paper,the Wavelet Packet Decomposition-Kullback Leibler-phase Modulation Index model and the Wavelet Packet Decomposition-Transfer Entropy model were established to describe the phase-amplitude coupling and the frequency-frequency coupling characteristics,respectively.The synchronous coupling relationship between EEG and EMG of stroke patients and healthy controls was analyzed,and the difference and abnormal mechanism of CFC characteristics after stroke were explored.By analyzing the the consistency of CFC characteristics and the clinical rehabilitation assessment scales,the auxiliary effect of CFC on the assessment of stroke rehabilitation status was verified.Firstly,the research status of stroke rehabilitation state assessment and the coupling relationship between EEG and EMG signals were briefly summarized in this paper.And then,the advanteges of functional corticomuscular coupling was described in detail.In view of the limitations in functional corticomuscular coupling analysis methods mainly from the perspective of iso-frequency coupling,a new idea of cross-frequency coupling between the brain and muscles was proposed.Secondly,based on the phase-amplitude coupling characteristics between different frequency bands of EEG and EMG signals,a new method of phase-amplitude coupling was proposed by combining the Wavelet Packet Decomposition and phase-amplitude modulation index models.The method can analyze the relationship between phase-amplitude coupling between tne brain and muscles cross different frequencies in the process of motor control system.The results showed that the method provides a new way of thinking for the study of the transmission of the neural oscillation between the different frequency bands in the neuromuscular system,and also provides the basis for the training of motor rehabilitation.Thirdly,based on the frequency-frequency coupling characteristics between EMG and EMG signals,the wavelet package decomposition-transfer entropy was introduced into the characteristic analysis models to explore the information transmission relationship in motor control.The experimental results showed that this method can effectively describe the frequency-frequency coupling mechanism of neural oscillations in the process of motor control.Finally,the correlation analysis between different coupling characteristic indexes of cross frequency coupling CFC of stroke patients and Ueda clinical scales was carried out to explore the clinical consistency.The consistency analysis results of three different correlation analysis methods showed that there were significant correlations between the phase-amplitude coupling or frequency-frequency coupling and the STM scales.The results showed that the phase-amplitude coupling and frequency-frequency coupling characteristics can be used to describe the coupling oscillation characteristics of neuromuscular system.