Cortical plasticity associated with Braille learning

doi:10.1016/S1364-6613(98)01172-3

Trends in Cognitive Sciences

Volume 2, Issue 5, 1 May 1998, Pages 168-174

https://doi.org/10.1016/S1364-6613(98)01172-3 Get rights and content

Abstract

Blind subjects who learn to read Braille must acquire the ability to extract spatial information from subtle tactile stimuli. In order to accomplish this, neuroplastic changes appear to take place. During Braille learning, the sensorimotor cortical area devoted to the representation of the reading finger enlarges. This enlargement follows a two-step process that can be demonstrated with transcranial magnetic stimulation mapping and suggests initial unmasking of existing connections and eventual establishment of more stable structural changes. In addition, Braille learning appears to be associated with the recruitment of parts of the occipital, formerly `visual', cortex (V1 and V2) for tactile information processing. In blind, proficient Braille readers, the occipital cortex can be shown not only to be associated with tactile Braille reading but also to be critical for reading accuracy. Recent studies suggest the possibility of applying non-invasive neurophysiological techniques to guide and improve functional outcomes of these plastic changes. Such interventions might provide a means of accelerating functional adjustment to blindness.

Section snippets

Enlarged somatosensory representation of braille-reading fingers

Evidence from both animal and human models suggests that somatosensory representation of a body part can be selectively remodeled by new tactile experiences, and that repeated use or stimulation of that portion of the body can lead to an enlarged cortical representation. The work of Merzenich and colleagues7, 8, 9, 10, 11using animal models suggests that these changes in cortical representation might underlie changes in perception. Recanzone et al.[12]found that the topographical and temporal

Occipital cortex activation in early-blind braille readers: true cross-modal plasticity

What becomes of those occipital portions of a blind individual's cortex that would otherwise have subserved visual processing? Can they be re-allocated to subserve new functions, or even different sensory modalities? The answer to the latter question, at least in the case of `early-blind' Braille readers (subjects born blind or that had become blind before the age of 7), appears to be yes. Using positron emission tomography (PET) as a measure of cortical activation during tactile discrimination

Using TMS to track the flow of spatial information in early-blind braille readers

Having demonstrated that the visual cortex of early-blind Braille readers is activated by tactile discrimination tasks, questions such as how and when tactile information reaches the visual cortex may be pursued. TMS is a useful method with which to approach these questions. Appropriately delivered in time and space, TMS can transiently disrupt the arrival of the thalamo-cortical volley of afferent signals into the primary sensory cortex and thereby interfere with detection of peripheral

Conclusions

Blind subjects demonstrate remarkable neuroplastic changes in response to the adjustment to blindness and the acquisition of Braille-reading skill. This reorganization appears to involve two distinct processes. First, there is enlargement of the somatosensory representation of the Braille reading finger, which probably reflects both rapid unmasking of existing cortical connections and slower, more enduring structural changes. Secondly, at least in early-blind subjects, the occipital, `visual'

Acknowledgements

Supported in part by grants from the Milton Fund, the Stanley Vada-NAMI Foundation, the Spanish Research Council (DGCYT), the General Clinical Research Center at BIDMC (NIH RR 01032) and the National Eye Institute (RO1 EY12091).

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Trends in Cognitive Sciences

Cortical plasticity associated with Braille learning

Abstract

Section snippets

Enlarged somatosensory representation of braille-reading fingers

Occipital cortex activation in early-blind braille readers: true cross-modal plasticity

Using TMS to track the flow of spatial information in early-blind braille readers

Conclusions

Acknowledgements

Trends Cognit Sci.

Neurosci. Lett.

Neurosci. Lett.

Electroencephalogr. Clin. Neurophysiol.

Electroencephalogr. Clin. Neurophysiol.

Brain Res.

Behav. Brain Res.

Neurosci. Lett.

Arrested vision

Sci. Am.

Neurophysiological correlates of hand preference in primary motor cortex of adult squirrel monkeys

J. Neurosci.

Functional reorganization of primary somatosensory cortex in adult owl monkeys after behaviorally controlled tactile stimulation

J. Neurophysiol.

Progressive improvement in discriminative abilities in adult owl monkeys performing a tactile frequency discrimination task

J. Neurophysiol.

Frequency discrimination training engaging a restricted skin surface results in an emergence of a cutaneous response zone in cortical area 3a

J. Neurophysiol.

Topographic reorganization of the hand representation in cortical area 3b of owl monkeys trained in a frequency-discrimination task

J. Neurophysiol.

Changes in the distributed temporal response properties of SI cortical neurons reflect improvements in performance on a temporally based tactile discrimination task

J. Neurophysiol.

Sensorimotor cortex representation of the reading finger of Braille readers: an example of activity-induced cerebral plasticity in humans

Brain

Crossmodal changes in the somatosensory vibrissa/barrel system of visually deprived animals

Proc Natl. Acad. Sci. U. S. A.