Analysis Of Brain Network For Motor Tasks Based On EEG Signals

Movement is one of the important functions of human beings and the analysis of the brain mechanism during movement is also a major focus of brain research.Studying the brain mechanism of the movement process can help us understand the cooperative relationship between different brain regions,provide a neurological basis for analyzing the causes of dyskinesia diseases and exploring new treatment methods;and then can also provide theoretical and technical support for designing Brain-Computer Interface System based on movement tasks.Current research indicates that there are multiple brain regions working together during the movement preparation stage and the movement execution stage.However,the interrelation between the brain regions has not been fully explored.Therefore,it is of great significance to study the functional coupling between brain regions during movement.(1)Two experimental paradigms of the self-paced movement and the externallytriggered movement were designed and the EEG signals of 10 subjects were acquisitioned and preprocessed.the effects of different reference electrodes on brain function network during movement were compared and analyzed.The results show that the Reference Electrode Standardization Technique(REST)can greatly reduce the effect of physical reference effect.(2)The time-domain and frequency-domain characteristics of EEG signals during movement were studied using event-related potentials and time-frequency representations.The results show that EEG signals in α,β,and γ frequency bands have more obvious characteristics and event-related desynchronization(ERD)has different distribution characteristics during the stages of movement preparation and movement execution.(3)The sensor-level brain function network was constructed using coherence,phase-locked value and phase lag index in the α and β frequency band during the selfpaced movement and the externally-triggered movement.Signals in the motor cortex,parietal cortex,prefrontal cortex and occipital cortex show higher phase synchronization than the resting stage.Activities in the α band are more obviously during movement execution,while activities in the β band are equally obvious during both movement preparation and execution.(4)The local and global properties of the functional network were analyzed using the degree distribution and global efficiency.The results show the following four views: the node degree of the nodes near the central left motor cortex of the brain increased significantly during the self-paced movement and the externally-triggered movement;the node degree of the frontal cortex is larger during the self-paced movement,and the node degree of the parietal cortex is larger during the externallytriggered movement;during the movement preparation stage,the degree distribution of the self-paced movement has a more obvious contralateral advantage than the externally-triggered movement;there is no significant difference in global efficiency of the brain function network between different task states.(5)The differences in connectivity and network properties of brain function networks during movement preparation stage and movement execution stage were compared using statistical method.The results show the following two views: the externally-triggered movement is more active in the network of occipital cortex and parietal cortex than the self-paced movement,and this difference is more obvious in the α band than in the β band;there is no significant difference in the global efficiency between the self-paced movement and the externally-triggered movement.