Complex Network Analysis Of Neuromuscular System For Precision Digit Force Control

The precision control of digit force is the key to dexterous manipulation.Under the influence of a variety of central(such as stroke)and peripheral(such as carpal tunnel syndrome)neuromuscular diseases,the ability of precision digit force control is vulnerable to damage,which will seriously affect the ability of patients to live independently.The existing rehabilitation techniques are unable to carry out targeted training for the ability of precision digit force control,and the rehabilitation training effect is not good.The main reason is the lack of accurate and quantitative calculation and evaluation of the neuromuscular system activities controlled by precision digit force.The neuromuscular system is a distributed complex system with functional separation and integration,and complex network technology can combine the local and global information flow of the neuromuscular system to study the neuromuscular regulation mechanism of precision digit force control.As a main manifestation of precision digit force control of the human body,precision grip is the most important manifestation of the functions of skilled hands in daily life.In this study,complex network technology is applied to the analysis of neuromuscular system functions for precision digit force control,and a large-scale weighted brain network based on phase delay index(PLI),a multi-layer muscle network based on horizontal visibility graph and multiple layer directional neuromuscular coupling network to explore the neuromuscular regulation mechanism in the process of precision grip.The main work of the thesis includes:(1)Construct a large-scale weighted brain network during the period of change in target force.Precision grip requires complex neuromuscular regulation and control.In daily life,the modulation ability of the linear change of digit force(linearly increase or decrease)plays an important role in the successful execution of precision grip.This study explores the effects of linear changes of digit force(speed of force change and rising and falling states)on force output performance and brain dynamic activities,in order to further understand the neuromuscular regulation mechanism of in the stable period of target force.Force output performance is characterized by accuracy(relative error,relative positive error,relative negative error)and variability(root mean square error,mean slope,coefficient of variation of the slope).The results show that the relative error and root mean square error in the rising and falling states of digit force increase significantly with the increase of the speed of force change.The mean slope of the force increases with an increase in the rate of change of the force and there is a higher value in the state where the force decreases.Graph theory analysis is performed on the large-scale weighted brain network constructed based on PLI to study the change of network topology characteristics with the linear change of digit force.The results show that as the speed of force change increases,the weighted clustering coefficient will increase and the characteristic path length will decrease.This change is mainly in the ?(4-8 Hz)and ?(14-30 Hz)frequency bands.At different speeds of force change,the local and global information flow will change related to the motor control regions.(2)Build a multilayer muscle network in the stable period of target force.When the human body moves,the central nervous system needs to coordinate multiple muscles.Especially in the process of precision grip,multiple arm muscles coordinate with each other through neural circuits to accurately adjust the magnitude and direction of digit force.Although there are many related researches on muscle synergy during power grip,little is known about the functional interaction between muscles during precision grip.This study studies the effect of precision digit force level(high stability period:10%maximum voluntary contraction force;low stability period:1%maximum voluntary contraction force)on the neural interaction between muscles from the perspective of complex network.The study takes the speed of force change as the research object to explore the effect of sensory motor processing state before the stabilization task on the muscle activity during the stabilization phase.The results show that the network structure of the multi-layer muscle network will change significantly at different levels of precision digit force.This change is related to the anatomy of the arm muscles,and the different muscle pairs are adjacent because of functional coordination.There are also strong connections on the matrix.The statistical analysis results of node degree and connection edge of conditional mutual information muscle network at different precision digit force levels show that different muscles have different influence on precision digit force control.The first dorsal interosseous plays a more important role in the stage of low stabilizing force.The changes in muscle network structure are more complex when the force changes more slowly.The precision digit force level and the speed of force change have different effects on the significance of different muscles,and will also affect the local and global network efficiency.The precision digit force level affects the similarity and consistency between all layers in the multi-layer muscle network.(3)Construct a multilayer neuromuscular coupling network in the stable period of target force.When the human body performs exercise,in addition to synergy between the brain areas related to sensory movement,the central nervous system and the peripheral nervous system related to muscle tissue also synchronize,and the intensity of synchronization reflects the degree of interaction between the central nervous system and the muscles.This study studies the changes in the state of neuromuscular functional coupling during precision digit force control from the perspective of a complex network to further understand the mechanism of neuromuscular coordinated control.The research results show that the neuromuscular coupling of precision digit force control is bidirectional,and the coupling state is different between different EEG-EMG channels.There is a directional information flow pattern in the neuromuscular coupling during the precision grip process,which is related to the frequency band.In the ?(4-8 Hz)frequency band,the brain has a more dominant information flow to muscle tissue,while in the ?(8-14 Hz),?1(14-25 Hz),?2(25-35 Hz)frequency bands the system does not have a preferred mode of information flow.In the y(35-70 Hz)frequency band,muscle tissue is more dominant in the information flow to the brain.The effect of precision digit force level on the neuromuscular coupling is not obvious,but mainly on the information flow between the central region of the brain and the muscles.