Study: 'Glitch' in brain circuitry hinders dyslexics

March 3, 1998
Web posted at: 5:37 a.m. EDT (0537 GMT)

NEW HAVEN, Connecticut (CNN) -- The part of the brain vital for reading does not function properly in people with dyslexia, a new study reveals for the first time.

Dr. Sally E. Shaywitz, a Yale University School of Medicine researcher, described the problem as "a glitch in the circuitry for reading" that makes it more difficult for dyslexics to translate written words into sounds.

To identify the brain circuitry problem, Shaywitz and her colleagues used a technique called functional magnetic resonance imaging, or MRI. This technology allows researchers to observe which parts of a subject's brain are active when a specific function is performed.

The researchers used the MRI technique on 29 dyslexic readers and 32 normal readers. They were all required to read a list of nonsense words that would rhyme if the reader could correctly link the letters with the language sounds that they symbolize.

As reading tasks in the test got more difficult, differences in brain activity were apparent.

"When we compare good and bad readers, we see very different brain organization patterns," Shaywitz said.

Shaywitz and her colleagues' results are to be published Tuesday in the Proceedings of the National Academy of Sciences.

Phonetics is key to improvement

Shaywitz said there are 44 letter sounds in the English language. They are represented by 26 letters in the alphabet, either singly or in combination.

In order to read, a person's brain must convert the printed letters into the sounds they represent.

In the functional MRI tests, Shaywitz said normal readers showed activity in both the portion of the forebrain that processes visual information, and in the back of the brain that contains the language center. And normal readers had no trouble interpreting the rhyming symbols and sounds.

For dyslexics, however, there was reduced activity in the language center at the back of the brain and increased activity in a part of the brain linked to the spoken word. And they were much less able to link the rhyming letters and sounds.

Having discovered the problem, researchers say the next big step is teaching how to treat the problem. Teaching children how to read phonetically -- sometimes referred to as "breaking the code" -- is especially important because an inability to read causes so many other learning problems, researchers said.

"Phonological awareness and phonological code breaking appear to be the best single way initially to teach kids to read," said Mark Griffith of the Eagle Hill School, a Connecticut school for students with learning disabilities.

Researchers plan to do a follow-up study. The doctors plan to evaluate dyslexic students who have been trained to read phonetically to see if this training changes their brain activity.

The Associated Press contributed to this report.

Correspondent Christine Negroni and The Associated Press contributed to this report.

Related sites:

Note: Pages will open in a new browser window

• Dyslexia: The Gift
• The Dyslexia Institute
• Dyslexia Online

External sites are not endorsed by CNN Interactive.

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