Dissertation
Dissertation > Medicine, health > Basic Medical > Medical science in general

A Study of Mechanism of ADHD Based on ALFF and Network Topology

Author WangWei
Tutor HuBin
School Lanzhou University
Course Circuits and Systems
Keywords ADHD Resting state fMRI ALFF functional connection Small worldnetwork
CLC R31
Type Master's thesis
Year 2013
Downloads 36
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Neuroscience and information science are two hot issues in modern natural science research, and the neuroinformatics is a new subject which combined the two subjects. More and more researchers focused their attentions on application of computational methods to study the brain and behavior.The amplitude of low frequency fluctuation (ALFF) measures the average efficiency of low frequencies of sequence signal. Correlation coefficient measures the strength of the linear relationship between two sequence signal. With the rapid development of computer technology, ALFF and the correlation analysis has been widely used to study the neural informatics.The study of complex networks has a strong interdisciplinary characteristics, research on brain networks have become a key research topic of brain research in twenty-first Century. Recently, many researchers have used graph theory to study the aberrant brain functions in mental disorders. However, the characteristics of the brain functional network in ADHD are still largely unexplored.In this study, the ALFF (0.01-0.08Hz) and functional connections were used to analyze blood oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) data for57children with attention deficit hyperactivity disorder (ADHD) and59healthy controls (HC) in a resting state. Compared with HC, the ADHD showed significantly altered neural activities and functional connections in the prefrontal cortex, temporal cortex and default mode network (DMN).The abnormalities in prefrontal and temporal cortex might provide evidence to support that functional abnormalities are extended from the prefrontal cortex to the temporal cortex in ADHD. In this study, fMRI data were employed to construct brain functional networks in ADHD groups and HC groups. Both groups had similar global efficiency; however, the ADHD group had significantly decreased local efficiency compared with the HC. The between-group differences of degree values were found in the frontal cortex, temporal cortex and DMN. The ADHD group retained most of the hub regions found in the HC, but showed altered hub regions in the left posterior cingulate gyrus and the right lingual gyrus. This altered topological organization of the functional network might be associated with the underlying pathophysiology in ADHD.This study on the one hand discovered some new ADHD pathological features.had a greater understanding of the pathophysiology of ADHD; on the other hand it also proved the effectiveness of apply computational methods to study mental disorders, point out the future study direction of mental disorders.

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