A New View on Dyslexia

Some 5 to 17 percent of U.S. children suffer from dyslexia, a learning disorder that makes it difficult to read. Many dyslexic children are able to make substantial improvements, but how they do so is not well understood, and standardized reading tests cannot predict which of them are likely to become stronger readers. Now MIT and Stanford researchers have shown, for the first time, that brain scans may be able to do just that.

The findings could help scientists and educators develop new teaching methods that take advantage of the brain pathways that dyslexic children appear to use to compensate for their disability, says John Gabrieli, a professor of brain and cognitive sciences and an author of the study. Such strategies may be able to help dyslexic children regardless of which brain patterns they show, although he adds that different strategies might be warranted depending on the brain pattern.

Gabrieli and colleagues studied 25 dyslexic children, all ranging from 11 to 14 years old, as well as 20 normal readers in the same age range. Each subject’s brain was imaged with functional magnetic resonance imaging (fMRI) as he or she decided whether pairs of words rhymed.

Two and a half years later, the researchers found that the dyslexic children who improved the most were those whose initial MRIs showed the most activity in the right prefrontal cortex and the strongest neural connections in the white matter—the nerve bundles that carry messages from one part of the brain to another—in the same area.

The right prefrontal cortex is believed to be involved in visual memory, ­Gabrieli notes. He says that dyslexic children may be using this area to memorize words. Other studies have shown that normal readers use the right prefrontal cortex less and less as they move from memorizing words to figuring them out “on the fly” by translating letters into sounds. That task requires language-­processing areas located in the left hemisphere.

The new findings suggest that dyslexic children who overcome their reading difficulties somehow bypass brain regions normally used for reading, says ­Gabrieli. “It seems like they’re better off using a completely different strategy,” he says.

Knowing which brain regions successful dyslexic students rely on could help educators develop new ways of teaching. One possibility would be to emphasize a more visual approach, similar to “speed reading,” as opposed to teaching dyslexic children to translate letters into sounds.