Brains different dyslexic are
A new study shows, for the first time, chemical differences in the brain function of children suffering the learning disability, dyslexia.
The research, published in the current issue of the American Journal of Neuroradiology, provides new evidence that dyslexia is a brain-based disorder. The interdisciplinary team of University of Washington researchers also showed that dyslexic children use nearly five times the brain area as normal children while performing a simple language task.
Dyslexia, a reading disorder, is the most common learning disability, affecting an estimated 5 percent to 15 percent of children.
"The dyslexics were using 4.6 times as much area of the brain to do the same language task as the controls," said Todd Richards, co-leader of the study. "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 Virginia Berninger, a professor of educational psychology.
The researchers used a novel, non-invasive 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. They measured levels of brain lactate, a by-product of energy metabolism produced by neurons. Most brain activity took place in the frontal lobe of the brain, known to be one of the centres for expressive language function.
The boys, fitted with earphones, were asked to perform four tasks while their brains were being imaged. Three of the tests involved pairs of words and the fourth used pairs of musical tones.
While the dyslexic boys exhibited nearly five times more brain lactate activation during a language task that asked them to interpret the sounds of words, there was no difference in the two groups during the musical tone test. This means the difference between the dyslexics and the normal children relates to auditory language and not to nonlinguistic auditory function, according to Richards and Berninger.
" It is not brain damage", says Berninger, "dyslexics often have enormous talents in other parts of their brain and shine in many fields. Einstein was a dyslexic and so were inventor Thomas Edison and financier Charles Schwab".
" What we found is a metabolic marker, but there could be a more fundamental cause. We need to understand the molecular and neural mechanisms underlying dyslexia," she added.