The Journal of Neuroscience, September 5, 2007, 27(36):9585-9594; doi:10.1523/JNEUROSCI.2650-07.2007
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Behavioral/Systems/Cognitive
Human Adult Cortical Reorganization and Consequent Visual Distortion
Daniel D. Dilks,1,3
John T. Serences,2,4
Benjamin J. Rosenau,2
Steven Yantis,2 and
Michael McCloskey1
Departments of 1Cognitive Science and 2Psychological and Brain Sciences, Johns Hopkins University, Baltimore, Maryland 21218, 3McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and 4Department of Cognitive Sciences, University of California, Irvine, California 92697
Correspondence should be addressed to Daniel D. Dilks, McGovern Institute for Brain Research, Massachusetts Institute of Technology, 46-4141G, Cambridge, MA 02144. Email: dilks{at}mit.edu
Neural and behavioral evidence for cortical reorganization in the adult somatosensory system after loss of sensory input (e.g., amputation) has been well documented. In contrast, evidence for reorganization in the adult visual system is far less clear: neural evidence is the subject of controversy, behavioral evidence is sparse, and studies combining neural and behavioral evidence have not previously been reported. Here, we report converging behavioral and neuroimaging evidence from a stroke patient (B.L.) in support of cortical reorganization in the adult human visual system. B.L.'s stroke spared the primary visual cortex (V1), but destroyed fibers that normally provide input to V1 from the upper left visual field (LVF). As a consequence, B.L. is blind in the upper LVF, and exhibits distorted perception in the lower LVF: stimuli appear vertically elongated, toward and into the blind upper LVF. For example, a square presented in the lower LVF is perceived as a rectangle extending upward. We hypothesized that the perceptual distortion was a consequence of cortical reorganization in V1. Extensive behavioral testing supported our hypothesis, and functional magnetic resonance imaging (fMRI) confirmed V1 reorganization. Together, the behavioral and fMRI data show that loss of input to V1 after a stroke leads to cortical reorganization in the adult human visual system, and provide the first evidence that reorganization of the adult visual system affects visual perception. These findings contribute to our understanding of the human adult brain's capacity to change and has implications for topics ranging from learning to recovery from brain damage.
Key words: cortical reorganization; cortical plasticity; primary visual cortex; perceptual distortion; adult human visual system; visual perception
Received Jan. 13, 2006;
revised July 17, 2007;
accepted July 19, 2007.
Correspondence should be addressed to Daniel D. Dilks, McGovern Institute for Brain Research, Massachusetts Institute of Technology, 46-4141G, Cambridge, MA 02144. Email: dilks{at}mit.edu
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[Abstract]
[Full Text]
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