Brain Imaging Could Help Target Dyslexia Interventions
New brain-imaging research at Stanford University has found distinct differences in the brains of dyslexic adolescents that may help predict who will be better or worse at compensating for their disability.
The study, published in the December Proceedings of the National Academy of Sciences, was led by Fumiko Hoeft, an associate director of neuroimaging applications at Stanford University School of Medicine, in collaboration with researchers from the Massachusetts Institute of Technology, the University of Jyväskylä in Finland and the University of York in England.
The researchers studied 45 students ages 11 to 14, 25 of whom who had been diagnosed with dyslexia based on a battery of tests of phonemic awareness, reading comprehension, speed and fluidity, spelling, vocabulary and the ability to rapidly name objects, letters, numbers and colors.
The team conducted on each child a functional magnetic resonance imaging, or fMRI scan, which reveals oxygen flowing to different parts of the brain during activities, and diffusion tensor magnetic resonance imaging, or DTI, which shows the neural connections active among different parts of the brain during activities. Each student was put into the imagers, then shown pairs of printed words and asked to identify which words rhymed, while researchers recorded the activity in their brains.
Two and a half years later, the researchers again tested the students' reading levels and compared the results to the initial brain scans. The graphic below, from the National Institutes of Health, shows how the brains of different students differed. As the left image shows, students who compensated better for their dyslexia had more neural connections in the superior longitudinal fasiculus, which is associated with processing visual text. As the center image shows, during rhyming these students also had increased brain activity in the inferior frontal gyrus, an area of the brain associated with the ability to manage ongoing activities. Contrast this to the image on the far right, in which brains of typically developing readers simply showed more brain activity on the left side during rhyming.
When the imaging results were included with a diagnostic formula, the researchers could predict more than nine times out of 10 which students would improve their reading skills two years later.
"This finding provides insight into how certain individuals with dyslexia may compensate for reading difficulties," said Dr. Alan E. Guttmacher, director of the National Institute of Health's Eunice Kennedy Shriver National Institute of Child Health and Human Development, which provided funding for the study, in a statement on the findings. "Understanding the brain activity associated with compensation may lead to ways to help individuals with this capacity draw upon their strengths. Similarly, learning why other individuals have difficulty compensating may lead to new treatments to help them overcome reading disability."
The study also highlights the ways neuroscience is starting to reveal variations among students with the same learning disabilities. Researchers hope to eventually use such studies to target educational interventions more closely to individual students' learning needs.