Using fMRI technology to understand hyperlexia
Washington, D.C. -- Georgetown University Medical Center researchers today published the first ever fMRI study of hyperlexia, a rare condition in which children with some degree of autism display extremely precocious reading skills. Appearing in Neuron, the case study uncovers the neural mechanisms that underlie hyperlexia, and suggest that hyperlexia is the true opposite of the reading disability dyslexia.
Hyperlexia is found in very rare cases in children who are on the "autism spectrum," meaning they display some characteristics of autism. Like autistic children, children with hyperlexia have extreme difficulty with oral communication, social interaction and expression, and yet can read surprisingly well at a very young age. By some accounts, hyperlexic children can read at 18 months, sometimes two years before they have ever uttered a single word. They are drawn to print, sometimes reading all the signs and license plates they might encounter during a brief walk through the parking lot.
The child in this case study, Ethan , reads six to eight years in advance of his age. He read dictionaries in his twos, but spoke his first word at age three and a half.
"This advanced reading ability, which would likely surprise any parent, is even more extraordinary given that many of these children begin reading before mastering spoken language, and sometimes before speaking at all," said senior author Guinevere Eden, DPhil, associate professor of pediatrics and director of Georgetown's Center for the Study of Learning. "Current theories of reading development posit that decoding skills are based on linguistic abilities, but our finding suggests that children like Ethan are able to map sound onto print without a solid language basis."
Eden and her colleagues use fMRI technology to study how brains develop and function as children learn to read. Most children acquire reading skills through explicit instruction received over several years of schooling. In this study, the research team wanted to illucidate the neural signature for precocious reading, which arose in the absence of any teaching. Deviations from the normal pattern would suggest that other regions of the brain might have the potential to become involved in the reading process and would shed light onto possible compensatory strategies of the abnormally reading brain.
The hyperlexic boy, Ethan performed several reading tests while lying down in the fMRI. The researchers then compared hot spots of brain activity in Ethan as he performed these tasks against brain scans of typically developing readers, who were matched to Ethan on either chronological or reading age. Compared to these groups, Ethan demonstrated greater activity in an area on the left side of the brain that is associated with understanding the sounds of speech as well as a region on the right side of the brain that is part of the visual system.
Co-author Peter Turkeltaub, a PhD student, draws an analogy of to the volume control on a radio. "A region of the brain implicated in reading skills, the left superior temporal cortex, is like a dial. When the dial is turned up, you find accelerated readers, or hyperlexics. When the dial is turned down, as has been shown for dyslexic children, you find inefficient readers. The more neurological research we do, the better we may understand how the dial works and what educational interventions may turn the dial toward its optimum point."
Ethan's parents knew something was peculiar with their son at a young age. He did not speak, make eye contact, or respond to typical verbal or non-verbal communications cues. However, he could sit silently in a corner and read books for hours.
Now at age eleven, Ethan attends a public school with an aide, and was recently voted class president. He has an insatiable curiosity for books, magazines, and television, but still has difficulty in social situations. According to his mom Ilene, "the other kids think he is very smart but very unusual. There are times when he says things that make the other kids realize he is not quite the same."
Ilene said, "If I could tell people one thing about hyperlexia, I would remind them that these children have a tremendous gift and that reading is the way to unlock their minds and hearts. Don't try to take their books away to force them to interact with people. Encourage their reading ability, because they have so much to offer the world, just in a more unconventional way."
"Neuroscience is allowing us to better characterize people who were before all bundled under the general autism umbrella," said Eden. "Just as it is extremely helpful to distinguish a child with Asperberger's, identification of hyperlexia can be equally as important for early intervention and appropriately tailored education."
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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