Proceedings of the National Academy of Sciences.
Literacy requires the integration of activity in brain areas involved in vision, hearing and language. These areas are distributed throughout the brain, so efficient communication between them is essential for proficient reading.
Jason Yeatman, a neuroscientist at Stanford University in California, and his colleagues studied how the development of reading ability relates to growth in the brain’s white-matter tracts, the bundles of nerve fibres that connect distant regions of the brain.
They tested how the reading skills of 55 children aged between 7 and 12 years old developed over a three-year period.
There were big differences in reading ability between the children, and these differences persisted — the children who were weak readers relative to their peers at the beginning of the study were still weak three years later.
The researchers also scanned the brains of 39 of the children at least three times during the same period, to visualise the growth of two major white-matter tracts: the arcuate fasciculus, which conects the brain's language centres, and the inferior longitudinal fasciculus, which links the language centres with the parts of the brain that process visual information.
Differences in the growth of both tracts could predict the variations in reading ability. Strong readers started off with a weak signal in both tracts on the left side of the brain, which got stronger over the three years. Weaker readers exhibited the opposite pattern.
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