Multisensory Motor Control Of Grasping And Application In Early Diagnosis Of Alzheimer’s Disease

The movement of the hand plays an important role in daily life.In recent years,analysis method of the sensory motion control about grasping movement has been continuously improved,mainly focusing on the single-factor sensory motion control,while the research on multi-perceptual motion control is relatively rare.With the aging of the population,the incidence of Alzheimer’s disease has also increased year by year,and Alzheimer’s disease causes different degrees of hand dyskinesia.Clinically,the early diagnosis of Alzheimer’s disease is mostly focused on questionnaires,but it is not good to prevent the occurrence of the disease.Therefore,the purpose of this thesis is to study the motion control of the brain under multi-sensory conditions,the control of the hand-grasping movement under the mirror system,and the three-dimensional grasping kinematics of the patients in Alzheimer s disease.We have found a control model for hand movement under multi-perceive conditions;at the same time,it is important to provide quantitative behavioral parameters for the early diagnosis and evaluation of clinical Alzheimer’s disease.This paper mainly completes the following work:1.Under the mirror system,the kinematics research of the reaching and grasping movement.Hand movement control requires integration of environmental factors,task requirements,and sensory information.The movement speed and coordination of the hand is a measure of the kinematic signal in the case of different environments,tasks,and sensory information afferent.The study designed the reaching-grasping kinematics experiment under the mirror system,which mainly includes three experimental environments:(1)grasping the real object,(2)grasping the virtual object,(3)grasping the real object with shielding the visual information of the hand.Then the speeds of all trials are normalized for a time,that is,a gripping cycle is resampled to 100 data points from 1 to 100.We compared the differences between the three normalized speeds.The results show that the speed of the hand is significantly affected by the following factors,which are the height of the object,the real and virtual of object and the virtual feedback of the hand(p<0.05).At the same time,in the case of movement coordination,it is found that under the visual feedback the coordination shows a negative correlation with the increase of height of the object;when grasping the higher object,the movement coordination is the worst.2.A kinematic study of sensorimotor control for lift-to-pour a glass of water.The sensory system is an essential component in the reaching-grasping movement.This study explores the movement control under multi-sensory when lifting and pouring a glass of water.First,the control of visual and tactile feedback is achieved by the type of measuring glass and the volume of the liquid(200 ml VS 400 ml),respectively.Secondly,the whole process is divided into four phases according to the manipulate task and the time point:the reaching phase,the lifting phase,the pouring stage and the replacing phase.We calculated the duration of each phase,as well as the fit slope of the glass deflection angle curve for the lifting,pouring,and replacing phases.It was found that the duration of the lifting phase and the pouring phase showed a positive correlation with the increase in liquid quality.At the same time,when grasping the heavier measuring cup(400 ml),the slope values of the lifting and pouring phases were significantly different between the left and right hands(p<0.05),showing that the slope value of the left hand was smaller than that of the right hand.The visual feedback of the object only affected the slope value of deflection curve during the lifting phase(p<0.05)for the left hand.However,the duration of the reaching and replacing phase,and the slope value of the replacing phase are not significantly different between factors.3.Early diagnosis method of Alzheimer’s disease based on three-dimensional space grasping motion feature calculation.In patients with Alzheimer’s disease,the memory function is reduced and the visual space skills are impaired,and hand movement function defects occur.The accuracy,precision and variability of the grasping movement,as well as the smoothness of the hand movement,provide a good assessment of hand function movement.In this experiment,we designed a three-dimensional space grasping experiment with Alzheimer’s disease,to record the spatial coordinates of the markers during the grasping movement.Kinematic parameters include the position and accuracy in the X,Y,and Z directions,accuracy and variability relative to virtual points,and hand motion smoothness(SPARC)throughout the grasping movement.The difference results showed that there was a significant difference between the control group and the healthy group in the X and Y directions position(p<0.05);the accuracy of grasping in healthy people was significantly higher than that in patients,mainly in the X direction.At the same time,the variability between the contact points determined by the thumb and index finger and virtual target points during the grasping movement is significantly increased for the patients.In the analysis of the smoothness,it was found that the difference between the patient group and the control group was mainly reflected in the absence of visual feedback.These results reflect that Alzheimer’s disease reduces the accuracy and precision of grasping,increases the variability of movement,and reduces the smoothness of movement,thus leading to reduced hand function in Alzheimer’s disease patients.