Blindness at different onset age provides us an exceptional example to investigate how the unimodal sensory deprivation affects the structure of human brain. Recently diffusion magnetic resonance imaging studies about blindness mainly focused on early blind, no previous research has examined the alteration of white matter in the whole brain and anatomical network across different onset age of blindness. In this dissertation, we focused on the following two topics: the first one investigates the brain anatomical network of different groups of blind subjects based on diffusion tensor tractography (DTT), and studies the relation between onset age of blindness and network properties; the second one investigates the abnormal diffusion change of white matter in the blind groups using tract-based spatial statistics (TBSS) methods, and studies the relation between onset age of blindness and the attributes of the white matter. The main content of this paper is as follows: We successfully constructed the binary anatomical networks of all subjects using DTT, and calculated topological properties of the network using a graph theory approach. In order to determine the effect of the onset ages on the brain anatomical network, we divided the 97 blind subjects into congenital blind (CB), early blind (EB), adolescent blind (AB) and late blind (LB) subgroups. Compared with normal sighted subjects, CB and EB demonstrated a reduced degree of connectivity, an increased path length and a decreased global efficiency, especially in the inferior frontal gyrus and visual cortex. However, no such difference was found in LB. We also revealed significant correlation between onset age of blindness and the network properties. The results suggest that visual experience at early developmental period is critical to establish an intact, efficient anatomical network of the human brain. In order to evaluate the influence of blindness onset age on the white matter integrity of whole brain, we employed TBSS to explore the difference of white matter integrity in five groups (CB, EB, AB, LB and normal controls). Our finding revealed that significantly changed white matter integrity was mainly located in the occipital lobe, the temporal lobe and the posterior limb of internal capsule. Compare with normal sighted controls, the white matter integrity of all the blind groups reduced in the occipital and temporal lobe, which may be due to transneuronal degeneration and/or immaturity. However...
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