Global ETD Search

1	Retinotopic Preservation in Deep Belief Network Visual Learning Lam, Michael January 2011 (has links) One of the foremost characteristics of the mammalian visual system is the retinotopic mapping observed in the low-level visual processing centres; the spatial pattern of activation in the lateral geniculate nucleus and primary visual cortex corresponds topologically to the pattern of light falling on the retina. Various vision systems have been developed that take advantage of structured input such as retinotopy, however these systems are often not biologically plausible. Using a parsimonious approach for implementing retinotopy, one that is based on the biology of our visual pathway, we run simulations of visual learning using a deep belief network (DBN). Experiments show that we can successfully produce receptive fields and activation maps typical of the LGN and visual cortex respectively. These results may indicate a possible avenue of exploration into discovering the workings of the early visual system (and possibly more) on a neuronal level. Visual Learning DBN Retinotopy Computer Science
2	Retinotopic Preservation in Deep Belief Network Visual Learning Lam, Michael January 2011 (has links) One of the foremost characteristics of the mammalian visual system is the retinotopic mapping observed in the low-level visual processing centres; the spatial pattern of activation in the lateral geniculate nucleus and primary visual cortex corresponds topologically to the pattern of light falling on the retina. Various vision systems have been developed that take advantage of structured input such as retinotopy, however these systems are often not biologically plausible. Using a parsimonious approach for implementing retinotopy, one that is based on the biology of our visual pathway, we run simulations of visual learning using a deep belief network (DBN). Experiments show that we can successfully produce receptive fields and activation maps typical of the LGN and visual cortex respectively. These results may indicate a possible avenue of exploration into discovering the workings of the early visual system (and possibly more) on a neuronal level. Visual Learning DBN Retinotopy Computer Science
3	Plasticity and Macular Degeneration: the Reorganization of Adult Cortical Topography Main, Keith Leonard 10 April 2007 (has links) This study evaluated whether cortical reorganization occurs in response to macular degeneration (MD), a progressive disorder of the retina that results in central vision loss. Past research has observed the ability of V1 to adapt to retinal damage, demonstrating that deafferented cortex is activated by the stimulation of intact retinal areas. It is still unclear, however, if and to what degree cortical reorganization is associated with specific forms of macular degeneration. This study evaluated the retinal health of MD participants (both age-related and juvenile) as well age-matched controls with computerized microperimetry. Contrast-reversing stimuli were then presented to different parts of the visual field while participants were scanned with functional magnetic resonance imaging (fMRI). For MD participants, stimulation of peripheral retinal areas elicited activation in deafferented cortex. This activation occurred for retinal areas adapted for eccentric viewing (preferred retinal locations), but not in preserved retina at the same eccentricity. These findings add to the scientific knowledge of plasticity in sensory systems by supporting an experience driven understanding of cortical reorganization. They could also have a meaningful impact on how macular degeneration is treated by informing the design of therapeutic training regimes. Macular degeneration Low vision Plasticity Retinotopy Cortical reorganization
4	An fMRI study of chromatic processing in humans / Untersuchung der menschlichen Farbverarbeitung mittels fMRT D'Souza, Dany Vijay 09 September 2009 (has links) No description available. 500 Naturwissenschaften MED 372 Mathematics and Natural Science fMRT Farbensehen visueller Kortex Retinotopie Isoluminanz Zeitfrequenz Ortsfrequenz Gesichtsfeld Exzentrizität chromatisch Leuchtdichte fMRI color vision visual cortex retinotopy isoluminance temporal frequency spatial frequency visual field eccentricity chromatic luminance 42.99 44.03

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