Diffusion tensor imaging (DTI) is a recently developed MRI technique. With this technique, the anatomical connections and neural circuits in the brain can be evaluated in vivo. In recent years, several studies have constructed the brain anatomical network using diffusion MRI to reveal the structural organization of the human brain. In this dissertation, we focused on the following two topics: the first one is about the abnormal diffusion and plastic changes of the cerebral white matter in the early blind; the second one is about the studies of the brain anatomical network based on DTI. The main contents and contributions of the dissertation are as follows: Blindness provides us a unique model for investigating how the brain structure and function were altered under general loss and multimodal plasticity for single sensory deprivation. The first purpose of this study is to explore the possible changed white matter regions of the early blind in whole brain manners, using voxel-based analysis (VBA) and tract-based spatial statistics (TBSS) methods. From VBA of fractional anisotropy (FA) images, the significant changed white matter regions were the geniculocalcarine tract (GCT) and its adjacent regions. This finding was validated by TBSS method. Then we revealed the changes of diffusion eigenvalues in the GCT, using tractography based group mapping analysis. And we suggest that transneuronal degeneration and/or immaturity may account for the abnormal diffusion changes in the GCT of the early blind. The second study is investigating the plastic changes of the corticospinal tract (CST) in early blindness by tract-based quantitative analysis. Compared with normally sighted controls, the integrity of the CST is significantly increased in the early blind men, which may reflect experience-dependent compensatory plasticity of the brain. The topological architecture of the cerebral anatomical network reflects the structural organization of the human brain. Recently, topological measures based on graph theory have provided new approaches for quantifying large-scale anatomical networks. The first study of my work about network is to investigate the abnormal connection pattern of the anatomical network in early blindness by DTI. We first established the existence of structural connections between any pair of the 90 cortical and sub-cortical regions using deterministic tractography for each subject. Compared with controls, early blind subjects showed a decreased degr...
修改评论