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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