Dyslexia Linked to Region of Brain
Monday, July 22nd 2002, 12:00 am
By: News On 6
Scientists have found new evidence linking the reading problem called dyslexia to glitches in a particular region of the brain.
The evidence comes from brain scans of 70 dyslexic and 74 non-impaired children, ages 7 to 18. It follows a 1998 brain scan study that reported the link in adults.
The new work, by including children as young as 7, shows the brain problem is present at the beginning of reading ability, said researcher Sally Shaywitz of Yale University.
She and colleagues reported the work in the July 15 issue of the journal Biological Psychiatry. They used functional magnetic resonance imaging, which reveals how hard various parts of the brain are working during particular tasks. The researchers cautioned the technology can't be used to diagnose dyslexia.
Their results showed that the better a child performed in tests of reading ability, the greater activation he or she showed in a particular brain area when trying to sound out words. That emphasizes that this region is key to skilled reading, as prior studies had suggested, Shaywitz said.
Children with dyslexia showed significantly less activation than normal in this area, a finding that fits with prior work, the researchers said.
The area, just behind the left ear, is called the left occipito-temporal region. Scientists are now trying to define just what circuitry is involved, as well as what goes wrong in dyslexia, Shaywitz said.
Older dyslexic children showed more activity in a different brain region than younger dyslexic children did. That suggests the other area was stepping in to compensate, allowing the children to read but only with great effort, Shaywitz said.