The use of IQ in diagnosing dyslexia, which affects 5 to 17 percent of U.S. children, has real implications for poor readers. If children aren't diagnosed as dyslexic, they don't qualify for services that a typical dyslexic does, and they're not taught strategies to overcome specific problems in the way they view and process words.
To further understand what happens in the brains of poor readers with different IQs, Hoeft turned to imaging. She and her colleagues expected poor readers with typical IQs to exhibit similar patterns of brain activation as poor readers with low IQs. Their experiments, she said, were intended to confirm that the two groups had the same neurophysiological basis for impaired phonological processing and that their reading problems were not related to IQ.
The study involved 131 children, ranging from 7 to 16 years old, from Allegheny County, Penn., and the San Francisco Bay Area. The children were put into three groups: poor readers with typical IQ, poor readers with low IQ and typical readers with typical IQ. The children then took a reading test and underwent a brain-imaging technique called functional magnetic resonance imaging, or fMRI, as they completed a task that involved judging whether two visually presented words rhymed (e.g., bait and gate) or not (e.g., price or miss).
In both samples, the typical readers had significantly higher reading-related scores and more accurate performance on the rhyme-judgment task than the two other groups. And there were no significant differences between the two groups of poor readers on these measures.
In the fMRI analysis, researchers found that both groups of poor readers exhibited significantly reduced activations relative to typical readers in the left inferior parietal lobule and left fusiform gyrus. The researchers also used a sophisticated analysis to determine that the brain patterns of each group
|Contact: Michelle Brandt|
Stanford University Medical Center