The brain always works as an integrative network. The study of brain functional connectivity and functional networks based on fMRI data has been one of the hottest topics of science. The main contents and contributions of the dissertation are as follows: We suggested that the altered functional connectivities in the resting state may be an integrated reflection of general loss and compensatory plasticity in the early blind. Blindness provides us a unique model for investigating how the brain function was altered under general loss and multimodal plasticity for single sensory deprivation. Firstly, we selected the primary visual area as a seed region and explored its functional connectivity pattern of it. Secondly, from a whole brain perspective, we investigated the decreased and increased functional connectivities in the early blind using resting state fMRI data. Our findings indicate that changes in the functional connectivities in the resting state may be an integrated reflection of general loss and compensatory plasticity when a single sensory modality is deprived. We investigated the alteration of the efficient small-world architecture of the brain functional networks in the patients with schizophrenia with resting fMRI More and more studies have indicated that schizophrenia may result from the improper functional integration among brain regions. Many previous neuroimaging studies have provided consistent evidences of “dysfunctional connectivity” among the brain regions in schizophrenia. We investigated the topological properties of human brain functional networks derived from resting-state fMRI. Our findings demonstrated that the brain functional networks had efficient small-world properties in the healthy subjects; whereas these properties were disrupted in the patients with schizophrenia. Specifically, we found that these altered topological measurements correlate with illness duration in schizophrenia. These findings are consistent with a hypothesis of dysfunctional integration of the brain in this illness. We explored the modularity of brain functional network and classified the roles of the brain regions Functional segregation and functional integration are two major organizational principles of the human brain functions. Large-scale brain connectivities, both structural and functional, have received a great deal of research attention, especially using the approach of complex network analysis.We demonstrated that we could classify nodes into universal roles according to their pattern of intra- and inter- connectors. Remarkably, we found that brain regions that participate in only a few reactions but connect different modules are more conserved than hub regions whose links are mostly within a single module. The method thus yields a ‘cartographic representation’ of brain functional networks, which may help us understand the functional segregation and functional integration in our brain.
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