Scientists believe that between 10 and 15 percent of the U.S. population suffers from dyslexia. This learning disability, was formerly thought to be caused by a difficultly in recognizing distinct language sounds. However, a new study has found that the cause of Dyslexia is a fault in a subject’s brain wiring that occurs between the left and right sides of their brain.
A dyslexic subject will often swap letters within words or words within a sentence, causing a reading, writing and comprehensive learning disability, even though they may have normal or even above-normal intelligence.
The professor of psychiatry at Belgium’s University of Leuven, Bart Boets, recently conducted a study of 23 people with dyslexia and a control-group of 22 without dyslexia. This study was also co-authored by experts in Switzerland’s ETH Zurich University, the University of Oxford, and the University College London.
This study was conducted using an advanced magnetic resonance imaging techniques (fMRI). The technique measured the unique pattern that sounds make in the test subject’s brain. Boet’s experiment showed that the quality of brain impressions were no different in either test groups.
The test revealed that both groups identified the sounds in the same way, but the group with dyslexia took approximately 50 percent longer to respond to them. This finding surprised Boets and other experts because it contradicted previous thoughts on what actually was to be causing this learning disability.
What the fMRI technique showed was impaired connections between the left and right auditory regions of the dyslexic subject’s brains. This auditory region, or Broca’s region, are where phonetic representations and higher level processing of the phonological sounds takes place.
Sequences of four partial words were used on the test subjects, followed by a change in one of the vowels or consonants. The subjects would listen to sequences such as, da-da-da-da and then ba-ba-ba-ba. Then they were asked what had changed between the first and last sequence they heard.
One of the dyslexia researchers, Hans Op de Beeck, clarified the analysis used in the study to a simpler metaphorical situation. Op de Beeck used the scenario of his daughter calling from home using his landline telephone to say she was home from school. He would understand that she was home, but wouldn’t be able to know why she was at home or what she was currently doing at home.
Boet’s also used a metaphor as a comparison. Boet’s compared his study’s findings to a computer network. The information exists intact on a computer data server, yet the connection to that information is either too slow or too degraded.
However, not all of Boet’s findings were welcomed by other dyslexia experts. San Francisco’s University of California neuroscientist, Michael Merzenich, did not accept Boet’s experiment with open arms.
Merzenich thinks that prior evidence showed dyslexics have a lower fidelity of processing than normal, when they are processing phonetic representations. Merzenich went on to say that past evidence contradicting Boet’s study was very compelling and extensive. He also said that this contradicting evidence just cannot be ignored.
Boet’s is hoping that the study will eventually lead to methods of improving the circuitry of the brain through non-invasive stimulation of the brain itself.
The next step for Boet’s in his dyslexia research is thought to see him studying more adult subjects and children inflicted with the disability. One theory is that Boet’s just may have found that adult dyslexics have been given more time for these regions to develop in their brains than normal adults.
By Brent Matsalla