Unraveling The Roots Of Dyslexia
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By peering into the brains of people with dyslexia compared to normal readers, a study published online on March 12th in Current Biology, a Cell Press publication, has shed new light on the roots of the learning disability, which affects four to ten percent of the population. The findings support the notion that the reading and spelling deficit — characterized by an inability to break words down into the separate sounds that comprise them — stems in part from a failure to properly integrate letters with their speech sounds.
“The adults with dyslexia in the study had enough reading experience to match letters and their speech sounds correctly,” said Vera Blau of the University of Maastricht, The Netherlands “Still, the results show that the way their brain integrates letters and speech sounds is very different from normal readers. It’s quite astonishing.”
The researchers examined activity in the brains of dyslexic and normal adult readers by using functional magnetic resonance imaging (fMRI) as they were presented with letters, speech sounds, or a matching or non-matching combination of the two. While undergoing that task, dyslexic adults showed lower activation of a brain region known as the superior temporal cortex than the more typical readers did.
The findings point to a neural deficit in letter-speech sound integration as a fundamental mechanism that might distinguish poor from good readers, Blau said. Such a difficulty in integrating the most basic units of written and spoken language could offer a promising link between well-documented difficulties in processing the sounds of language (phonology) and the actual reading problem itself, she added.
Her team, led by Leo Blomert at the University of Maastricht, is currently conducting further studies in children as they are learning to read to help identify whether the difficulty to integrate letters with speech sounds begins in early school years and whether it comes before or after deficits in processing the sounds of language.
In addition to enhancing scientists’ fundamental understanding of the disability, the new results might also have some ultimate implications for therapy. “Our findings may offer a way to validate intervention strategies and narrow down the best training approaches,” Blau said. Indeed, in a new series of studies, the group is investigating whether training strategies focused on phonological skills as well as letter-sound associations improve reading skills by changing activity levels in the brain of dyslexic readers.
[Cathleen Genova @ Cell Press]
One Comment
John Hayes
March 16th, 2009
at 9:36pm
I read these fMRI studies of dyslexia and the brain all the time and on a positive note these researchers took a slightly different approach and seem to have reasonable follow up research planned.
I would suggest that their investigation is probably of the most common dyslexia problem and is likely to apply to a majority of dyslexics. Studies that help to identify when these problems first occur should also be useful information in understanding dyslexia.
I will even go as far as to suggest that if someone was limited to reading only 1 fMRI study that this one wouldn’t be a bad choice for understanding what dyslexia is. Reading earlier studies of different areas of the brain and dyslexia would show that this isn’t a giant leap forward but it is an incremental step and that is all that can really be expected.
The title ” Unraveling The Roots Of Dyslexia” is a little overblown and the reporting and conclusions are of the usual poor quality as is common to almost all these fMRI studies.
It leaves the reader of the report the impression that if you are dyslexic that is how your brain will show up with a fMRI and implies that an individual dyslexic could be identified in that manner. That would be real news and I am sure would be clearly stated if that was the case.
To date, these studies do see differences between groups of dyslexics and non dyslexics but because different dyslexics have individualistic sets of problems not all dyslexics have any 1 particular problem to be identified by looking at any one area it is not possible to identify individual dyslexics this way.
Their suggestion that teaching phonics helps dyslexics has already been proven to be helpful to a majority of dyslexics.
My niche is visual dyslexia where reading difficulties are caused by problems seeing text in a clear and stable manner. Some visual dyslexics have the problems described in the study and some don’t. More information about visual dyslexia can be found at dyslexiaglasses.com .