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The Journal of Neuroscience, March 4, 2009, 29(9):2768-2773; doi:10.1523/JNEUROSCI.5258-08.2009

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Brief Communications
Reorganization of Visual Processing in Macular Degeneration Is Not Specific to the "Preferred Retinal Locus"

Daniel D. Dilks,¹ Chris I. Baker,² Eli Peli,³ and Nancy Kanwisher¹

¹McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and ²Laboratory of Brain and Cognition, National Institute of Mental Health–National Institutes of Health, Bethesda, Maryland 20892, and ³Schepens Eye Research Institute, Harvard Medical School, Boston, Massachusetts 02114

Correspondence should be addressed to Daniel D. Dilks, McGovern Institute for Brain Research, Massachusetts Institute of Technology, 46-4141, Cambridge, MA 02139. Email: dilks{at}mit.edu

Recent work has shown that foveal cortex, deprived of its normal bottom-up input as a result of macular degeneration (MD), begins responding to stimuli presented to a peripheral retinal location. However, these studies have only presented stimuli to the "preferred retinal location," or PRL, a spared part of the peripheral retina used by individuals with MD for fixating, face recognition, reading, and other visual tasks. Thus, previous research has not yet answered a question critical for understanding the mechanisms underlying this reorganization: Does formerly foveal cortex respond only to stimuli presented at the PRL, or does it also respond to other peripheral locations of similar eccentricity? If foveal cortex responds to stimuli at PRL because it is the long-term habitual use of this region as a functional fovea that drives the formerly foveal cortex to respond to stimuli presented at the PRL (the "use-dependent reorganization" hypothesis), then foveal cortex will not respond to stimuli presented at other locations. Alternatively, it may be that foveal cortex responds to any peripheral retinal input, independent of whether input at that retinal location has been chronically attended for months or years (the "use-independent reorganization" hypothesis). Using fMRI, we found clear activation of formerly foveal cortex to stimuli presented at either the PRL or an isoeccentric non-PRL location in two individuals with MD, supporting the use-independent reorganization hypothesis. This finding suggests that reorganization is driven by passive, not use-dependent mechanisms.

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Received Oct. 31, 2008; revised Jan. 9, 2009; accepted Jan. 27, 2009.

Correspondence should be addressed to Daniel D. Dilks, McGovern Institute for Brain Research, Massachusetts Institute of Technology, 46-4141, Cambridge, MA 02139. Email: dilks{at}mit.edu

This article has been cited by other articles:

				D. D. Dilks, C. I. Baker, Y. Liu, and N. Kanwisher "Referred Visual Sensations": Rapid Perceptual Elongation after Visual Cortical Deprivation J. Neurosci., July 15, 2009; 29(28): 8960 - 8964. [Abstract] [Full Text] [PDF]

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