Journal Article

Cross-modal plasticity revealed by electrotactile stimulation of the tongue in the congenitally blind

Maurice Ptito, Solvej M. Moesgaard, Albert Gjedde and Ron Kupers

in Brain

Published on behalf of The Guarantors of Brain

Volume 128, issue 3, pages 606-614
Published in print March 2005 | ISSN: 0006-8950
Published online January 2005 | e-ISSN: 1460-2156 | DOI: http://dx.doi.org/10.1093/brain/awh380
Cross-modal plasticity revealed by electrotactile stimulation of the tongue in the congenitally blind

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In sensory substitution, information acquired with one sensory modality is used to accomplish a task which is normally subserved primarily by another sensory modality. We used PET to study cross-modal plasticity in the congenitally blind, using electrotactile stimulation of the tongue. Blind (n = 6) and sighted blindfolded controls (n = 5) were scanned before and after they were trained to use their tongue in a Snellen orientation detection task. Results showed that both groups of subjects learned the discrimination orientation task after seven 1 h training sessions. Before training, no significant changes in regional cerebral blood flow (rCBF) were observed in the occipital cortex in either group. In sharp contrast, activity in the occipital cortex increased after practice for the blind, but not for the sighted, providing evidence for training-induced plasticity in the blind. An inter-regional correlation analysis showed that task-related rCBF changes in left posterior parietal cortex were positively correlated with rCBF changes in the occipital area of the trained blind. These data reveal that cross-modal plasticity in the blind develops rapidly and that the occipital cortex is part of a functional neural network for tactile discrimination in conjunction with the posterior parietal cortex. Our data further show that the tongue can act as a portal to convey somatosensory information to visual cortex.

Keywords: sensory substitution; cross-modal plasticity; vision; blind; brain imaging; LOtv = lateral occipital tactile-visual area; rCBF = regional cerebral blood flow; TMS = transcranial magnetic stimulation; TDU = Tongue Display Unit

Journal Article.  5666 words.  Illustrated.

Subjects: Neurology ; Neuroscience

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