How Learning to Read Changes Cortical Networks for Vision & Language

My friend and colleague Dr. Gary Williams shares a passion with me.  We are unabashed bibliophiles.  Some might call us bookaholics.  No mind – we’re beyond figuring out how to reform ourselves and more into celebrating what a wonderful vice it is to have.  We are intrigued about how reading has changed not only our brains, but brains in general, as well as the extent to which visual abilities factor into reading.  Along those lines we have gained much insight from a prolific and well-regarded researcher, Stanislas Dehaene.

Though we had read of Dehaene’s work on the significance of the occipito-temporal region of the brain in reading, and what he has termed the Visual Word Form Area, this was crystallized in Deahene’s widely acclaimed book, Reading in the Brain.  You can get a good flavor of his body of work through his bibliographic material here.  One of the reasons that we champion Dehaene’s work is that he is known among our colleagues as the “Anti-Shaywitz”.  Sally Shaywitz, an influential researcher at Yale University, is credited for championing the movement toward dyslexia as a phonological problem as opposed to a visual problem.  This undue emphasis on phonology being at the root of reading difficulty resulted in a disregard among some researchers and clinicians for the visual aspects of reading difficulties, though sources such as the Eides have fought well to maintain balance.

An article by Dehaene and his colleagues in the December 3, 2010 issue of the journal Science helps restore vision to its prominent place in the role of reading acquisition.

 

Here are some key points:

1) With the acquisition of literacy, written materials strongly activate the right occiptal cortex and the left ventral visual cortext at the classical site of the visual word form area (VWFA).

2) The initially broad bilateral visual network progressively restricts to the VWFA, and is similar to the developmental progression seen in young children as they acquire reading skills.

3) Literacy leads to a general enhancement of occipital responses.  It boosts the organization of visual cortices, particularly by inducing an enhanced response to known script at the VMFA in left occipito-temporal cortex, and by augmenting early visual responses in occipital cortex in a partially retinotopic manner.

Essentially Dehaene presents a visual Matthew Effect for reading.  The more a child reads, the more the visual areas that support reading are primed.  Even if you’re not fluent in French, you might enjoy this presentation by Dehaene in which he demonstrates how visual regions form a mosaic in the brain, and that the occipito-temporal region is primed developmentally for reading acquisition between 6 and 10 years of age.

http://www.youtube.com/watch?v=z7IG4s9kSPI

- Leonard J. Press, O.D., FCOVD, FAAO