Synchronization Analysis Of EEG Signals In Upper Limb Movement

Electroencephalogram(EEG)is the external manifestation of synchronous electrical activities of cortical neurons.The synchronous relationship of EEG is an important feature of information transmission and functional integration in the cerebral cortex.Research on synchronization of EEG in different areas of cerebral cortex has become a hot topic in the field of brain neurology.This paper mainly studies the synchronization of EEG in motor-related areas of human upper limbs.Grip experiment was designed to collect EEG signals from healthy subjects and stroke patients respectively.Based on the collected EEG,the coherence analysis of the two-channel EEG,bidirectional coupling analysis of two-channel EEG and the synchronization analysis of the multi-channel EEG are carried out.The synchronization relationship of the EEG is studied from various angles.The main contents of the paper are as follows:(1)Coherence analysis of two-channel EEG.Mutual Information estimation precision depends on the data length,the permutation mode is introduced.Considering that physiological system is a complex non-linear multiple scales system,multi-scale weighted permutation mutual information is used to characterize the coherence of multi-scale and multi-band EEG during grip output.Coherence analysis of two-channel EEG in motor cortex and sensory cortex during grip output of healthy subjects and stroke patients.It was found that the synchronization intensity of EEG in contralateral motor area and sensory area was the most significant in the ? band when gripping force was output.The synchronization intensity of EEG in stroke patients was lower than that in healthy subjects.And the synchronization intensity of EEG in healthy subjects increased with gripping force.(2)Bidirectional coupling analysis of two-channel EEG.Coherence cannot study the direction of information flow interaction between EEG signals,multi-scale permutation transfer entropy was used to analyze the bidirectional coupling relationship between the motor area and the sensory area in the grip output of healthy subjects and stroke patients.It was found that there was a bidirectional coupling relationship between EEG of motor area and sensory area.The coupling strength of EEG was strongest in ? band.Coupling analysis of EEG in ? band showed that the coupling strength of EEG signals with conventional hand grip force output is stronger than that with non-conventional hand grip force output.The ability of information interaction between motor area and sensory area of stroke patients is weaker than that of healthy people.(3)Synchronization analysis of multi-channel EEG.As two-channel EEG analysis can not study the synchronization of the whole cerebral cortex or a certain area of the cortex.The S-estimator algorithm is used to solve this problem.The original synchronization analysis of two-channel EEG is extended to the synchronization analysis of multi-channel EEG.The synchronization of EEG signals from multiple channels in the area around the central sulcus of the cerebral cortex was analyzed.It was found that the synchronization of C3 and C4 channels in motor area and CP5 and CP6 channels in sensory area was the strongest,and the synchronization intensity was the most significant in ? band.By analyzing the synchronization intensity of EEG signals in ? band,it was found that the synchronization of multi-channel EEG of stroke patients was weaker,indicating that the information interaction of cerebral cortex was weaker than that of healthy people.