Brain doesn't need vision at all in order to 'read' material

Feb 22, 2011

The portion of the brain responsible for visual reading doesn't require vision at all, according to a new study by researchers from the Hebrew University of Jerusalem and France.

Brain imaging studies of blind people as they words in Braille show activity in precisely the same part of the brain that lights up when sighted readers read. The findings challenge the textbook notion that the brain is divided up into regions that are specialized for processing information coming in via one sense or another, the researchers say.

"The brain is not a sensory machine, although it often looks like one; it is a task machine," said Dr. Amir Amedi of the Hebrew University of Jerusalem, head of the team of researchers whose work on the topic is reported in the latest issue of .

"A particular area fulfills a unique function, in this case reading, regardless of sensory input modality," he said. Amedi is affiliated with the Institute for Medical Research Israel-Canada and the Edmond and Lily Safra Center for Brain Sciences at the Hebrew University.

Unlike other tasks that the brain performs, reading is a recent invention, about 5,400 years old. Braille has been in use for less than 200 years. "That's not enough time for evolution to have shaped a brain-module dedicated to reading," Amedi explained.

Nevertheless, have shown that a very specific part of the brain, known as the Visual Word Form Area or VWFA for short (first discovered in sighted people by Dr. Laurent Cohen of Paris, a co-author of the current article), has been co-opted for this purpose. But no one knew what might happen in the brains of blind people who learn to read despite the fact that they've had no visual experience at all.

In the new study, Amedi's team, which included his doctoral student Lior Reich, used (fMRI) to measure the neural activity in eight people who had been blind since birth while they read Braille words or nonsense Braille. If the brain were organized around processing sensory information, one might expect that Braille reading would depend on regions dedicated to processing tactile information, Amedi explained. If instead the brain is task-oriented, you'd expect to find the peak of activity across the entire brain in the VWFA, right where it occurs in sighted readers, and that is exactly what the researchers saw.

Further comparison of brain activity in the blind and sighted readers showed that the patterns in the VWFA were indistinguishable between the two.

"The main functional properties of the VWFA as identified in sighted are present as well in the blind, and are thus independent of the sensory-modality of reading, and even more surprisingly do not require any visual experience," the researchers wrote. "To the best of our judgment, this provides the strongest support so far for the metamodal theory of brain function," which suggests that brain regions are defined by the computations they perform. "Hence, the VWFA should also be referred to as the tangible word-form area, or more generally as the (metamodal) word-form area."

The researchers suggest that the VWFA is a multisensory integration area that binds simple features into more elaborate shape descriptions, making it ideal for the relatively new task of reading.

"Its specific anatomical location and strong connectivity to language areas enable it to bridge a high-level perceptual word representation and language-related components of reading," they said. "It is therefore the most suitable region to be taken over during reading acquisition, even when reading is acquired via touch without prior ."

Amedi said he and his research associates plan to examine brain activity as people learn to read Braille for the first time in order to find out how rapidly this takeover happens. "What we want to find out is: how does the change to process information in words and is it instantaneous?"

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Eikka
5 / 5 (4) Feb 22, 2011
If the brain were organized around processing sensory information, one might expect that Braille reading would depend on regions dedicated to processing tactile information


Was it established that the brain regions dedicated to visual information weren't adapted to tactile information, which would mean that the blind person has learned to "see" with their fingers, and the reading still occurs through the visual pathways now re-purposed?
Caliban
5 / 5 (3) Feb 22, 2011
Yes -might this area of the brain be responsible for conceptualizing physical stimuli? That's essentially what words are for on a basic level- to convert more or less concrete sensory data into to an abstract form, in order to make the actual sensory input transferrable to another person without the need for them to undergo the actual experience themselves.
A_Paradox
5 / 5 (1) Feb 23, 2011
Gotta say I agree with Eikka and Caliban so far. Has anybody been able to access the original article?

It would be instructive to see comparisons of MRI scans for sighted persons reading, sighted persons blindfolded and 'reading' 3D word models with their hands, blind from birth people reading Braille, and so forth.

One thing I have noticed for many years is that when emptying my pockets in the dark, last thing at night, and making sure everything is in place at my bedside, for each thing I touch, recognise and put in its place, there is a fleeting "image" of the thing which seems both visual and tactile. And I mean complete darkness.
Ethelred
5 / 5 (1) Feb 28, 2011
Try spending a few hours in a darkroom finding bottles and pouring chemicals by touch only. After a while I found touching things was activating a sort of B&W vision. I think it was partly due to my trying to visualize what I was touching and remember where it was.

Of course I can see when the light is on. Then again a lot of people have the idea that blindness means not being able to see at all. Most blind people have some vision.

Ethelred

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