The long range goal of this project is to use functional magnetic resonance imaging (FMRI) to elucidate the brain mechanisms responsible for normal vision and for brain-related visual pathologies. As a new technology for studying brain function, FMRI is potentially revolutionary because it can produce high resolution pictures and movies of dynamic brain activation during sensory input, task performance, or cognitive activity. Since it is non-invasive and has no known health risks, hundreds of images can be obtained from a single subject, thus permitting detailed and thorough studies of brain function in both human and animal subjects. This project seeks to develop and test this technology further and then apply it to the study of visual perception. Fortunately, the neural basis of vision in monkeys is sufficiently well understood to provide a solid background for interpreting the results of FMRI experiments and for comparing and interrelating visual mechanisms in human and simian species. This will permit the knowledge gained in previous animal experiments to be applied more directly to the study of the human nervous system. To this end, the specific aims of the project are: 1) to determine the parametric relationships between the FMRI signal and visual stimulation, 2) to use FMRI to study the functional specialization of cerebral cortex by creating maps of topographic and functionally selective activation within and among different cortical visual areas in both humans and monkeys, 3) to use FMRI to record and analyze the temporal and spatial evolution of cortical activity during prolonged visual tasks, and 4) to explore the potential application of FMRI in the assessment of visual deficits resulting from cortical pathology. To accomplish these aims, a high magnetic field strength MR scanner (Bruker 3 Tesla) will be used to image cortical activation during computer controlled visual stimulation delivered via a custom designed optical system. Using novel computer algorithms, the 3-dimensional patterns of activation will be displayed on unfolded, two-dimensional maps of the cortical surface. Ultimately, these techniques will be used to study abnormal brain activation in a small number of patients with well characterized visual deficits. The goal will be to explore the potential use of FMRI in the assessment of brain pathology. The results of this project will provide new insight into the relationships between physical brain mechanisms and both normal and impaired perceptual experience. In addition, the testing and refinement of the FMRI technology will contribute significantly to the development of a powerful new tool for medical science.
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