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Stephen Engel, Peng Zhang, Min Bao, Miyoung Kwon, Sheng He; Effects of orientation specific visual deprivation in adults measured using altered reality. Journal of Vision 2009;9(8):848. doi: 10.1167/9.8.848.
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© ARVO (1962-2015); The Authors (2016-present)
Environmental manipulations produce strong cortical plasticity in developing animals (e.g. “stripe-rearing”), but few methods are available to alter the environment of adult humans. We developed novel technology to allow manipulations targeted to known visual mechanisms, and demonstrated it by removing energy from the environment at a specific orientation. Eight subjects viewed the world using an “altered reality” system, comprised of a head mounted gray-scale video camera that fed into a laptop computer that in turn drove a luminance calibrated head-mounted display (HMD). Energy at a narrow range of orientations across all spatial frequencies was removed from the video images prior to their display. This filtering was done in real time on the laptop computer using a simple mask in the Fourier domain. Viewing the filtered video images through the HMD, subjects were able to interact with the world, while being deprived of input at a specified orientation. Prior to and following a four-hour period of deprived visual input, contrast detection thresholds were measured for sinusoidal patterns at the removed orientation and at the orthogonal orientation. Patterns were 6 degrees in size, had a spatial frequency of 1 cycle per degree, and were presented centered 8 degrees in the periphery. Thresholds for the removed and orthogonal patterns were equal prior to the deprivation period. Following deprivation, thresholds for the removed orientation were reliably lower (by 18% on average) than thresholds for the orthogonal orientation. Thus visual sensitivity to the deprived orientation improved, suggesting an increase in the gain of orientation selective mechanisms. The altered reality technology should be able to produce a variety of environmental manipulations useful for studying plasticity in many different visual mechanisms.
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