Plasticity of Human Brain Networks as Revealed by Functional Magnetic Resonance Imaging

Author: Sung-Lai Yuen,

ISBN/ASIN: 1374669156

This dissertation, "Plasticity of Human Brain Networks as Revealed by Functional Magnetic Resonance Imaging" by Sung-lai, Yuen, 袁崇禮, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled Plasticity of human brain networks as revealed by functional magnetic resonance imaging Submitted by YUEN Sung Lai For the degree of Doctor of Philosophy at the University of Hong Kong in May 2007 The whole concept of "neural plasticity" has attracted a lot of research attention for its potential benefit to many people living with the sequalae of various brain pathologies. Via environmental influences and internal neurochemical activities, our brain exercises its potential of organizing itself in such a way that functions could be maximized. This thesis reports a series of neuroimaging studies that examines three forms of neural plasticity, namely 1) training-induced plasticity; 2) plastic change of brain circuitry after congenital or early sensory deficit; and 3) reorganization of neural circuitry after recovery from brain injury. In study one, we trained a group of healthy volunteers on a novel task that associates auditory signals with spatial information. Results showed that continuous training reduced activities in the general executive circuit supporting general task performance but increased activities in task-specific sensory processing regions. The coupling between general executive circuit and task-specific sensory regions may form the basis of training-induced connectivity. 1In study two, we recruited a group of blind subjects who were deprived of visual input either congenitally or very early in their lives. Their performance on the same experimental task of study one suggested that congenital or early sensory deprivation may result in an alteration of the functioning of the occipital regions. Furthermore, the pattern of brain activities observed in the blind group was significantly different from that of the sighted group. In study three, we showed that recovery after damage to the executive circuit may regain part of the function via reorganizing the brain circuits. Our findings are consistent with an information processing framework that describes the changes of brain activities, in the task-specific sensory regions and in the general executive circuit, associated with neural plasticity resulting from training and early environmental influences. Theoretical and clinical implications of the findings were discussed.

DOI: 10.5353/th_b3883760 Subjects: Neuroplasticity Nervous system - Magnetic resonance imaging Brain - Magnetic resonance imaging

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