Brain Imaging Study Eliminates Differences in Visual Function as a Cause
of Dyslexia - June 5th 1013
WASHINGTON-- A new brain imaging research of dyslexia shows that differences in the visual system do not cause the disorder, but instead are likely a result. The findings, published today in the diary Neuron, provide vital ideas into the reason for this common reading condition and address a long-standing dispute about the role of visual signs observed in developing dyslexia.
Dyslexia is the most prevalent of all learning handicaps, impacting about 12 percent of the U.S. population. Past the mostly observed reading deficits, individuals with dyslexia commonly also exhibit subtle weaknesses in processing visual stimuli. Researchers have supposed whether these deficits stand for the main reason for dyslexia, with visual disorder straight impacting the capacity to discover to read. The current study shows that they do not.
"Our results do not mark down the presence of this particular type of visual deficit," says senior author Guinevere Eden, PhD, director for the Center for the Study of Learning at Georgetown University Medical Center (GUMC) and past-president of the International Dyslexia Association. "In reality our results confirm that differences do exist in the visual system of kids with dyslexia, however these distinctions are the end-product of less reading, when compared to normal readers, and are not the reason for their struggles with reading.".
The current study follows a report published by Eden and coworkers in the journal Nature in 1996, the first study of dyslexia to use useful Magnetic Resonance Imaging (fMRI). As in that research, the brand-new study likewise reveals less activity in a section of the visual system that processes relocating visual details in the dyslexics compared with normal readers of the same age.
This time, however, the research group also studied more youthful kids without dyslexia, matched to the dyslexics on their reading level. "This group looked just like the dyslexics in regards to brain activity, providing the first clue that the observed difference in the dyslexics relative to their peers could have more to do with reading ability than dyslexia per se," Eden clarifies.
Next, the children with dyslexia received a reading intervention. Intensive tutoring of phonological and orthographic abilities was offered, addressing the core deficit in dyslexia, which is extensively thought to be a weak point in the phonological element of language. As anticipated, the kids made considerable gains in reading. In addition, task in the visual system increased, recommending it was set in motion by reading.
The researchers mention that these searchings for can have crucial effects for practice. "Early identification and treatment of dyslexia must not revolve around these deficits in visual processing," says Olumide Olulade, PhD, the research's lead author and post-doctoral fellow at GUMC. "While our study showed that there is a sturdy connection in between individuals's reading capacity and brain activity in the visual system, it does not suggest that training the visual system will lead to better reading. We think it is the other way around. Checking out is a culturally imposed ability, and neuroscience research has revealed that its acquisition results in an array of anatomical and functional changes in the brain.".
The analysts add that their research can be used more broadly to other conditions. "Our research has crucial implications in comprehending the etiology of dyslexia, however it likewise is relevant to other conditions where cause and outcome are challenging to pull apart since the brain changes in feedback to experience," discusses Eden.
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