Functional Integration Of Mirror Neuron System And Sensorimotor Cortex Under Virtual Self-Actions Visual Perception

With the advantages of immersive visual experience,virtual reality(VR)technology has been more and more applied in the rehabilitation of motor deficits after stroke.The functional integration of the mirror neuron system and the sensorimotor cortex under motor vision perception is one of the theoretical bases for the application of action observation in the neurological rehabilitation of motor deficits after stroke.Compared with traditional motion observation,VR technology has the advantage of immersive visual experience,but can such visual experience change further promote the functional integration of mirror neurons and sensorimotor cortex? Such visual perception of body actions in VR scene changes the activity and connection mode of neurons,which may positively promote the functional integration between the mirror neuron system and the sensorimotor cortex.Most of the existing studies on the use of VR in motor deficits rehabilitation focus on the comparison of rehabilitation effects,and lack of research on the neurophysiological principle and basic analysis of the causes of the effects.In this thesis,the integration mechanism of the mirror neuron system and the sensorimotor cortex in VR was studied by brain functional network,and the influences of the change of action observation perspective on neuronal activation and functional integration in VR visual perception were explored.Three control experiments were set up in VR scenes to study the neural mechanism between mirror neurons and sensorimotor cortex under the experimental conditions of first person perspective(1PP)self-action observation,third person perspective(3PP)action observation and actual execution of self-actions in VR scene.The functional integration between the core cortices of the mirror neuron system and the sensorimotor cortex under the visual perception of virtual body actions was studied by using EEG source location method based on eLORETA and cortical brain functional network analysis of region of interest(ROI)based on lagged phase synchronization,so as to further reveal the effect of VR on improving motor rehabilitation in the neural mechanism.These studies have achieved the results that VR action observation can further improve the functional integration of mirror neurons and sensorimotor cortex in terms of the mechanism of neural rehabilitation,which will be beneficial to the rehabilitation of motor deficits after stroke.The main contents and innovations of this thesis are as follows:(1)In the time domain of EEG signals,eLORETA was used to locate cortical power sources at peak points of total mean event-related potential(ERP)components under 1PP and3 PP experimental conditions.The results showed that the maximum source of the peak point of total mean ERP components at 1PP and 3PP was from the cortex associated with visual processing.At the same time,the right inferior parietal lobule(IPL,BA40)under 1PP and the right superior parietal lobule(SPL,BA7)and the left inferior frontal gyrus(IFG,BA45)under 3PP showed more significant signals in the distribution of neural electrical sources,which were only second to the visual contact area.This indicates that VR virtual action images under the experimental conditions in this thesis not only significantly activate the visual processing-related cortices,but also activate part of the core cortices of the mirror neuron system more obviously than other cortices.(2)Even if the experiments were repeated and the data were superposed and averaged,the voxel current densities of the cortex obtained by eLORETA were still significantly different from that of different subjects under the same experimental conditions,indicating the uncertainty of EEG signals among different subjects.In order to obtain reliable analysis results,it is necessary to conduct statistical analyses of all subjects' data between experimental conditions.In this study,statistical nonparametric mapping method(Sn PM)was used to analyze the difference of significance between experimental groups in time domain and frequency domain of whole cerebral cortex tracing results.The results of time domain analysis showed that the relative increase of EEG potentials at 1PP was significantly correlated with the activation of two core cortical regions of mirror neurons,the dorsal and ventral premotor cortex(PMD/PMV,BA6)and superior parietal lobule(SPL,BA7)(P<0.05),indicating that the activation of part of the core cortices of the mirror neuron system at 1PP generated higher EEG potentials than that at 3PP.In addition,the results of frequency domain analysis showed that the ? band current density in the superior parietal lobule(SPL)and the inferior parietal lobule(IPL,BA40)showed a stronger inhibition response at 1PP,resulting in more significant event-related desynchronization.These results suggest that,compared with 3PP,the observation of self-actions under 1PP has a greater activation effect on mirror neurons in the dorsal and ventral premotor cortex and parietal lobe regions.(3)The functional integration of motor information in the brain is the result of the communication of cortical information in multiple brain regions,so the connectivity analysis of different cortical regions is of great significance to the representation of brain functional integration.Based on the source location results of EEG signals in the frequency domain,the cortical functional connectivity analysis method with lagged phase synchronization was used to construct the cortical functional network based on the ROI,and the difference degree between experimental conditions was statistically tested for the cortical functional network under three experimental conditions:1PP,3PP and self-action execution.The results showed that the virtual visual perception of self-actions under 1PP had a more positive effect on the functional integration between the core cortices of the mirror neuron system and the sensorimotor cortex than that under 3PP.At the same time,the observation of virtual selfactions under 1PP can produce no significant statistical difference in the function integration effect compared with the self-action execution of the core cortices of the mirror neuron system and the sensorimotor cortex in a high proportion of 83.3%,and even produce greater local connectivity in a small part of the mirror neuron core cortices.In terms of neurophysiological mechanism,the above research results indicate that the virtual visual reproduction of self-actions in VR scenes further stimulates the activities of the core cortices of the mirror neuron system and promotes the functional integration of the core cortices of the mirror neuron system and the sensorimotor cortex.