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The learning disability dyslexia may be the result of different neurological conditions in readers of dissimilar languages, according to a new study that compared readers of English to those of Chinese (Proceedings of the National Academy of Sciences Online, April 7, 2008).
Previous neuroimaging studies revealed that dyslexic readers of alphabetic languages like English have decreased gray matter volume and weak reading-related activity in posterior regions of the brain compared to readers of character-based languages.
Li-Hai Tan, PhD and colleagues at the University of Hong Kong studied Chinese children with dyslexia to assess whether these abnormalities were universal. Using two imaging techniques, voxel-based morphometry, which assesses brain volume, and functional magnetic resonance imaging, the researchers discovered that readers of Chinese, a logographic, character-based language, had impairments in different brain regions than readers of alphabetic languages.
Specifically, Chinese children with dyslexia had structural and functional deficits in the left-middle frontal gyrus region, which is important for the coordination of cognitive resources in working memory, while their more posterior brain systems remained unaffected.
The authors suggested that the research may help physicians tailor therapies for the approximately 17 percent of schoolchildren affected by dyslexia worldwide.
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