Today at the annual meeting of the American Association for the Advancement of Science (AAAS) in San Francisco, scientists from Georgetown University and elsewhere are presenting new evidence that suggests a biological cause lies behind dyslexia, a learning disability that makes it difficult for some people to read with ease. Guinevere Eden and Thomas Zeffiro, co-directors at the Georgetown Center for the Study of Learning, used functional magnetic resonance imaging (fMRI) to study the brains of 37 participants20 with dyslexia and 17 without the disorder. They discovered that all of the subjects used similar brain areas for both reading and processing visual motionbut that the dyslexics' brains showed less activity during both tasks.

"Unfortunately, today we are able to diagnose dyslexia only after children have shown difficulty in learning to read, usually around the time they're in second or third grade," Zeffiro says. "But if we know that the same areas of the brain used for reading are also used to perform other types of visual tasks, then we can test children before they reach reading age to determine whether those areas work properly. A biological marker of this type might give us the chance to intervene before reading failure has occurred."

To that end, the researchers conducted a second study in collaboration with Frank Wood and Lynn Flowers of Wake Forest University Medical Center. The team divided 20 dyslexic adults into two groups and took baseline fMRI scans. One group then participated in an intensive eight-week program to improve their reading skills. The other group received no intervention whatsoever. The first group did show measurable improvements in reading after the training, and when the scientists again scanned their brains, they discovered that this group also showed related changes in neural activity. "It was quite exciting to be able to see such clear confirmation of our hypothesis in the fMRI scans," Eden remarks. "This is a great step towards better understanding the neural mechanisms involved in reading and learning."