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Neural networks for Braille reading by the blind
N Sadato1, A Pascual-Leone, J Grafman
1Human Motor Control Section, Medical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, Maryland 20892-1428, USA.
Brain : a Journal of Neurology
|July 29, 1998
Summary
Blind individuals reroute tactile processing to visual brain areas for Braille reading. This neuroplasticity involves activating the visual cortex and occipital regions, unlike sighted individuals who use somatosensory areas.
Area of Science:
- Neuroscience
- Neuroimaging
- Sensory Neuroscience
Background:
- Braille reading relies on tactile sensory input.
- Understanding the neural basis of Braille reading in the blind is crucial for insights into brain plasticity.
Purpose of the Study:
- To investigate the neural networks engaged during Braille reading in early-blind individuals.
- To compare tactile processing in blind and sighted individuals using non-Braille tasks.
Main Methods:
- Positron Emission Tomography (PET) was used to measure regional cerebral blood flow.
- Tasks included Braille reading and non-Braille tactile discrimination (angle, width, character).
- Participants were proficient Braille readers (blind) and sighted control subjects.
Main Results:
- Braille reading activated bilateral visual cortex (primary visual cortex, superior occipital gyri, fusiform gyri) and parietal regions in blind subjects.
- Blind subjects showed activation in ventral occipital regions during non-Braille tactile tasks, while secondary somatosensory areas were deactivated.
- Sighted subjects exhibited the reverse pattern: activation of secondary somatosensory areas and suppression of ventral occipital regions during tactile tasks.
Conclusions:
- Tactile processing pathways are rerouted in blind individuals, utilizing ventral occipital cortical regions typically associated with visual processing.
- This demonstrates significant neuroplasticity, where the brain adapts visual areas for non-visual sensory tasks like Braille reading.
- Findings highlight the brain's remarkable ability to reorganize in response to sensory deprivation.