Dyslexic children use nearly five times the brain area as normal children while performing a simple language task, according to a new study by an interdisciplinary team of University of Washington researchers. The study shows for the first time that there are chemical differences in the brain function of dyslexic and non-dyslexic children.
The research, published in the current issue of the American Journal of Neuroradiology, also provides new evidence that dyslexia is a brain-based disorder. Dyslexia, a reading disorder, is the most common learning disability, affecting an estimated 5 percent to 15 percent of children.
The UW researchers, headed by developmental neuropsychologist Virginia Berninger and neurophysicist Todd Richards, used a novel noninvasive technique called proton echo-planar spectroscopic imaging (PEPSI) to explore the metabolic brain activity of six dyslexic and seven non-dyslexic boys during oral language tasks. The researchers used PEPSI to measure levels of brain lactate activation. Lactate is a by-product of energy metabolism produced by neurons when the brain is activated. Most, but not all, of this brain activity took place in the left anterior, or frontal, lobe of the brain, which is known to be one of the centers for expressive language function.
"The dyslexics were using 4.6 times as much area of the brain to do the same language task as the controls," said Richards, a professor of radiology. "This means their brains were working a lot harder and using more energy than the normal children."
"People often don't see how hard it is for dyslexic children to do a
task that others do so effortlessly," added Berninger, a professor of
educational psychology. "There are learning differences in children. We can't
blame the schools or hold teachers accountable for teaching dyslexic children
unless both teachers and the schools are given specialized training to deal with
Contact: Joel Schwarz
University of Washington