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Alyssa A. Brewer, Brian Barton, Ling Lin; Putting the Prisms Back On: Both Maps of Visual Space Persist, as Revealed by Rapid Cortical Re-adaptation to Left-Right Visual Field Reversal. Journal of Vision 2010;10(7):899. doi: 10.1167/10.7.899.
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© ARVO (1962-2015); The Authors (2016-present)
Introduction: In this study, we exploit the dynamic nature of posterior parietal cortex to examine cortical functional plasticity induced by a complete reversal of visual input in normal adult humans. Using retinotopic fMRI measurements, we have previously demonstrated changes within the spatial representations of multiple parietal visual field maps following extreme alterations of visual input from left-right reversing prisms (Lin et al, VSS 2009). Data from adult barn owls suggest that after long-term adaptation to a large shift in visual input from prisms the altered representations of visual space persist (Linkenhoker and Knudsen, 2002). Here we investigate whether there is a difference in the timing or degree of a second adaptation to the left-right visual field reversal in adult humans after long-term recovery from the initial adaptation period. Methods: Three subjects previously participated in a 14-day continuous adaptation to left-right reversing prisms. These same subjects returned for a 4-day re-adaptation to the reversed visual field 1-9 months later. Subjects again performed a daily battery of visuomotor testing and training. We used traveling wave stimuli to measure the occipital and partietal visual field maps in each subject before, on the 4th day, and one day after the 4-day re-adaptation period. The receptive field alterations within these maps across time points were analyzed using the population receptive field method (Dumoulin and Wandell, 2008). Results/Conclusion: The data demonstrate a faster time course for both behavioral and cortical re-adaptation. By the end of this much shorter re-adaptation period, the measurements again show a shift of visual field representation from contralateral towards ipsilateral visual space in parietal cortex. These measurements of cortical visual field maps in subjects with severely altered visual input demonstrate that the changes in the maps produced by the initial long prism adaptation period persist over an extended time.
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