Study On Function Of Human Visual Cortex Based On Functional Magnetic Resonance Imaging

Visual research is an important approach to understand advanced functions of human brain, such as information processing, learning and memory, abstract thinking and so on. As a new technology to explore the functional activities of brain, functional magnetic resonance imaging (fMRI) has the advantages of non-invasion, non-radialization and high temporal and spatial resolution. Based on fMRI, function of human visual cortex is studied in this dissertation, retinotopic mapping technique is realized and studies of contrast sensitivity and visual motion perception are conducted at the level of human brain function. The details are shown as follows:1. Under the experimental paradigm of eccentricity/polar angle stimuli, visual areas of human cortex were outlined using VFS method based on 3D volume data set. In all subjects, V1-V8 areas were delineated clearly. The visual areas were distributed on the occipital cortex as topological frame.2. Based on fMRI retinotopic mapping technique, visual cortical deficit of contrast sensitivity in human amlyopia was studied creatively. Responses were compared between the fellow fixing and amblyopic eye in V1-V8 visual areas, the deficits in primary and secondary visual cortex were analyzed regressively. The result showed that: There were functional deficits in both primary and secondary visual cortex and no linear correlations between the activation loss of striate and extra-striate cortex in amblyopes. The method can observe the cortical deficit within each retinotopic visual area, and provides a deeper insight into the amblyopia from the pathophysiologic point of view.3. Under the block-design/steady state experimental paradigm, changes of functional connectivity network related to visual motion function in different brain activity were investigated by combing spatial independent component analysis with temporal correlation. The experiment indicated that: The functional connectivity network of V5 was more extensive and was consistent with the known anatomical connectivity during rest; when subjects were viewing motion, the network was limited in the visual cortex suggesting that V5 was acting in concert with a network specific to the visual motion processing task. The method is simple and efficient, and provides a deeper understanding of the dynamic working manner of human brain at the system level.