The Analysis And Application Of Modular Control Of Movements In Normal Subjects And Patients Post Stroke

Research of motor control reveals the neurophysiology during movement generation and regulation,it lays the foundation for promoting the development of motor control theory,and further directing the clinical treatment and rehabilitation for motor dysfunctions.In human,the sensorimotor system needs to cooperate the complicated movement and sensory signals to guarantee accurate posture and movement,and also the various of well-coordinated voluntary movements.The underlying mechanism is what motor control research need to figure out.Injuries in sensorimotor system usually lead to alternations of posture,movement,and their coordination,which might even threaten patients'health and life.In our country,motor dysfunction post stroke has brought great burden for medical,economic and social care.It's quite essential to further clarify the underling mechanism of motor control,and assist in more efficient clinical practice in stroke rehabilitation.In this study,we looked into the modular control mechanism of movement,and impact of stroke on modular control strategies,and its implications for clinical assessment of motor function and rehabilitation indication in patients post stroke.In this study,the modular control mechanisms contains modular control of posture and movement,and also the coordinated modules in more challenging tasks.Understanding motor dysfunction of stroke requires the motor control modules in healthy condition.In the central nervous system,the close loop composed by descending movement commands and sensory feedback ensures accurate posture and movement.While,the neural interaction in posture and movement remains unclear,due to neuropsychological limitations.Here,we incorporated movement physiology of upper limb from healthy subjects into a computational neuromusculoskeletal model,to find a plausible regulatory mechanism of muscle and spindle by?and?motor signals during posture and movement.By the light of neuropsychological findings,we constructed the independent modules of posture and movement within the corticospinal virtual arm model.Posture was maintained by static(?_s,?_s)motor commands,and movement were realized by dynamic(?_d,?_d)commands.The static and dynamic commands project to their innervating neural substrates in separate pathways.The commands of?and?were formulated based on human experiments and previous recording results.Simulation results showed similar kinematics and muscle activities of experimental posture and movement.This framework illustrated the plausible modules of independent posture and movement control,also implies that,coordinated?and?commands on muscle and spindles were essential for fine posture and movement control.On the basis of movement and sensory regulation during posture and movement,the sensorimotor system is capable of coordinating the highly complex musculoskeletal system,and producing smooth and skilled voluntary movements.Muscle synergy has been widely accepted as the optimized control strategy and neural substrate in the central nervous system,it is based on modules of muscular group,and explains the spatial and temporal characteristic of neuromuscular system.Muscle synergy helps with the understanding of neuromuscular coordination,which contributes greatly in motor function,the alternation of muscle synergy might carry important information on motor function,which could assist in assessment of motor dysfunction and training indication in stroke rehabilitation.We then expanded into the coordination mechanism of neuromuscular system under both healthy and stroke condition,and its inspiration for motor function assessment and recovery in stroke rehabilitation.Considering the difficulty and necessity of rehabilitation in upper limb activity,we focus on specific forward and lateral reaching tasks by upper limb.Muscle activities of each healthy subject and patient of each task were extracted into synergy vector(muscle weight in functional group)and time profile(activation profile of corresponding vector).Baseline synergy patterns were obtained from the pooled healthy subjects,patients showed individual alternations from baseline patterns.Three similarity indices were proposed to quantify patients'synergy performance,and they showed significant correlation with patient's kinematic performance and clinical score.The similarity index showed its potential in explaining and assessment the neuromuscular function between patients with varying impairment levels.Patients'motor function could change along with training,while,the impact of training on neuromuscular coordination during movement,and whether similarity indices of muscle synergy could discriminate this change remain to be observed.We applied the muscle synergy performance analysis on evaluation of motor recovery after training of functional electrical stimulation.Patients participated in this task-oriented continuous experiments,which included stimulation assisted training of arm reaching movements,and two evaluation tests before and after training.We analyzed patients'synergy performance before and after the training.The comparison showed improvement of synergy performance after stimulation,and indices of synergy and part of motor function indicators changed with the same trend.The result explained the change of motor function from perspective of neuromuscular coordination,synergy performance analysis might be a promising assessment of motor recovery rehabilitation.Meanwhile,change of spatial and temporal characteristics of muscle activities could be useful in the plan of further intervention strategies.In conclusion,this research analyzed the modular control strategy under healthy and post-stroke conditions.It first looked into the neural interaction in independent module of posture and movement by means of experiment and simulation incorporation,and further explored the neuromuscular coordination strategy by muscle synergy analysis.It illustrated the plausible modular control mechanism of simple and complex movements under healthy condition,and showed indication for clinical stroke rehabilitation.The results introduces a new computational framework and method of analyzing neural control of movement,and proposed a neuromuscular prospective of movement function assessment and intervention instruction for motor recovery of stroke.