The Journal of Neuroscience, November 15, 2001, 21(22):8931-8942
Impact of Early Deafness and Early Exposure to Sign Language on
the Cerebral Organization for Motion Processing
Daphne
Bavelier1,
Craig
Brozinsky1,
Andrea
Tomann1,
Teresa
Mitchell2,
Helen
Neville2, and
Guoying
Liu3
1 Brain and Cognitive Sciences Department,
University of Rochester, Rochester, New York 14627-0268, 2 Department of Psychology, University of Oregon,
Eugene, Oregon 97403-1227, and 3 Georgetown Institute for
Cognitive and Computational Sciences, Georgetown University,
Washington, DC 20007
This functional magnetic resonance imaging study
investigated the impact of early auditory deprivation and/or use of a
visuospatial language [American sign language (ASL)] on the
organization of neural systems important in visual motion processing by
comparing hearing controls with deaf and hearing native signers.
Participants monitored moving flowfields under different conditions of
spatial and featural attention. Recruitment of the motion-selective
area MT-MST in hearing controls was observed to be greater when
attention was directed centrally and when the task was to detect motion features, confirming previous reports that the motion network is
selectively modulated by different aspects of attention. More importantly, we observed marked differences in the recruitment of
motion-related areas as a function of early experience. First, the
lateralization of MT-MST was found to shift toward the left hemisphere
in early signers, suggesting that early exposure to ASL leads to a
greater reliance on the left MT-MST. Second, whereas the two hearing
populations displayed more MT-MST activation under central than
peripheral attention, the opposite pattern was observed in deaf
signers, indicating enhanced recruitment of MT-MST during peripheral
attention after early deafness. Third, deaf signers, but neither of the
hearing populations, displayed increased activation of the posterior
parietal cortex, supporting the view that parietal functions are
modified after early auditory deprivation. Finally, only in deaf
signers did attention to motion result in enhanced recruitment of the
posterior superior temporal sulcus, establishing for the first time in
humans that this polymodal area is modified after early sensory
deprivation. Together these results highlight the functional and
regional specificity of neuroplasticity in humans.
Key words:
motion; visual attention; fMRI; plasticity; deafness; American sign language
Copyright © 2001 Society for Neuroscience 0270-6474/01/21228931-12$05.00/0
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