This study demonstrated the relationship between brain connectivity and childrens reading abilities. For the behavioral part, the participants received proper reading interventions based on their ...responsiveness, and the standardized behavioral tests were administered throughout the process. For the imaging part, both T1-weighted images and diffusion weighted images were acquired. Nine cortical regions in each brain hemisphere were identified as regions of interest (ROI). The probabilistic streamlines connecting each pairing of the nine regions were calculated and used to estimate brain connectivity. The estimates were then used to correlate with childrens reading measures. Eight significant correlations were found, four of which were connections between the insular cortex and angular gyrus. The results are suggestive of a key role of connection between insular cortex and angular gyrus in mediating reading behavior. In spite of the limited sample size, the redundancy in the spread of group clusters is indicative of a relation between brain connectivity and childrens responsiveness to intervention.
Reading is a complex cognitive behavior, which relies on the incorporation of a network of brain regions. White matter is the information transfer pathway between distant brain regions, and thus ...plays an important role in mediating reading ability. Diffusion Tensor Imaging (DTI) is an MR technique to characterize white matter microstructure by probing the propensity of water molecules¡¯ diffusion in in vivo tissues. This dissertation seeks to investigate the reading network in the brain using diffusion MRI. The first part of the dissertation studies the cortical network with a focus on the putative visual word form area (VWFA), which is reproducibly found to be selectively recruited by visual orthographic conversion. We studied the structural connectivity patterns of the VWF-system in children with typically developing (TD) reading ability and with reading difficulty (RD). We found that the architecture of the VWFA connectivity is fundamentally different between TD and RD groups, with TD showing greater connectivity to linguistic regions than RD, and RD showing greater connectivity to visual regions than TD. The second part of the dissertation studies subcortical-cortical network, with a focus on the thalamus, the way-station of information transfer in white matter. Abnormal thalamo-cortical connectivity was found in the RD group in sensorimotor, orbital frontal and insula cortices. These results suggest that the thalamus plays a key role in reading behavior by mediating the functions of task specific cortical regions. Despite the valuable information DTI can provide, it suffers from fundamental limitations, especially when multiple fiber bundles are present. To address this problem, the third part of the dissertation proposes a new method to study complex white matter structures. It improves the current spherical deconvolution method by relaxing the assumption that all fiber bundles share the same response kernel. The in vivo experiments show that this Multiple Kernel Spherical Deconvolution (MKSD) approach can identify crossing fiber bundles and simultaneously provide an estimate of the diffusion properties intrinsic to each fiber bundle.
High-resolution diffusion tensor imaging (DTI) is beneficial for probing tissue microstructure in fine neuroanatomical structures, but long scan times and limited signal-to-noise ratio pose ...significant barriers to acquiring DTI at sub-millimeter resolution. To address this challenge, we propose a deep learning-based super-resolution method entitled "SRDTI" to synthesize high-resolution diffusion-weighted images (DWIs) from low-resolution DWIs. SRDTI employs a deep convolutional neural network (CNN), residual learning and multi-contrast imaging, and generates high-quality results with rich textural details and microstructural information, which are more similar to high-resolution ground truth than those from trilinear and cubic spline interpolation.
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