Monday, September 24, 2012

fMRI of Dysgraphia - Lack of Automaticity and Need for Visual Monitoring

Thank goodness for Todd Richards and his collaboration with Virginia Berninger and her group for looking into the brain-basis of dysgraphia.

In this interesting fMRI study, good and poor child writers were compared on a task of writing a  new pseudoletter. The 'good writers' (scored in the normal or higher range on WIAT writing test) showed a strong coordination between the cerebellum (motor-sensory feedback) and primary motor-sensory areas in the precental and postcentral gyrus.

Poor writers had a very different pattern. Their cerebellar activation was stronger in midline structures (trunk > fingers) and also visual areas of cortex were much more active than primary motor-sensory areas around the central gyrus. This result is very interesting - because in the clinic, we often see that students require much more visual monitoring of their letter formation (increases the labor, working memory requirement, and general tedium of writing by hand), and this greatly slows processing speed.

Sorry we haven't had time to regularly update this blog. But will let more articles trickle. I'm going to speak at the AACAP (American Academy of Child and Adolescent Psychiatry) next month and Brock at the annual meeting of the International Dyslexia Association - so our time's been swamped more than usual over our usual clinic.

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http://www.springerlink.com/content/apj42004p68445vm/

3 comments:

  1. Very interesting! Do you have a reference for the article. I would love to read more.

    Thanks, Theresa

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  2. Extra visual cortex activity? Fascinating...this would seem to support what a lot of teachers say, that dyslexic readers seem to rely more on a visual memory strategy for learning to read.

    Is there also increased activity in the prefrontal cortex for dyslexic writers? This is the usual neural signature for having to put in extra conscious effort, so activity here would support the idea that the neural correlates for dyslexics in this study reflect increased effort.

    Thanks for sharing!

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  3. Often there is increased prefrontal cortex activity while dyslexic students work at a task - indicating the increased work necessary...or more conscious effort.

    The full reference for the article is here:
    Reading and Writing
    May 2011, Volume 24, Issue 5, pp 493-516
    Differences between good and poor child writers on fMRI contrasts for writing newly taught and highly practiced letter forms
    Todd L. Richards, Virginia W. Berninger, Pat Stock, Leah Altemeier, Pamala Trivedi, Kenneth R. Maravilla

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