Research On Brain Functional Networks Based On FMRI In Different States

The human brain is considered as the most complex and perfect system in dynamic information processing,and the research on its functional network has become one of the most challenging international researches in the field of science.In this thesis,the brain functional networks of three states of resting,emotion and working memory are studied based on functional magnetic resonance imaging(fMRI)technology.In this thesis,the significance and development of brain functional network based on fMRI are overviewed firstly.The experimental design is described,and the preprocessing is made.The experimental data are standardized in both time and space fields,and the erroneous data of subjects and the noises are removed.Then,the human brain is divided into 116 regions using the Automated Anatomical Labeling(AAL)brain template.Each brain region is considered as a region of interest(ROI).The wavelet transform coherence(WTC)method is used to measure the functional connectivity between any two ROIs and hubs are deduced by node degree and betweenness centrality.Based on the results of functional connectivity and hubs,the topological properties and the activation of the brain are discussed.The simulation results show that three kinds of brain networks have very distinct properties of small-world.The activations of brain are different obviously under different conditions,and the brain working on the complex working memory task is more active than that on the other two kinds of states.Finally,the brain functional networks of emotion task and working memory task are studied on time sequential segmentation based on node degree.The results show that the activities of human brain are different in different stages of the same state,even in the different blocks of the same task.These indicate that the human brain can make an accurate and rapid response to the external environment,and activate the different functional brain regions according to the complexity of environment.