Links for Keyword: Dyslexia
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Genetic variations that cause miscues in brain development may play an important role in dyslexia, according to new research presented last week at a meeting of the American Society of Human Genetics in Salt Lake City. People with dyslexia have reading impairments despite normal intelligence. The problem affects between 5% and 17% of the population. In the last few years, geneticists have begun to point the finger at particular genes (ScienceNOW, 22 February). However, little is known about how these genes might contribute to the condition. In one new study, a collaboration of 20 researchers led by Haiying Meng and Jeffrey Gruen of Yale University School of Medicine homed in on a region of chromosome 6 that has been implicated in previous dyslexia studies. Using DNA collected from 536 people with a dyslexic in their families, the researchers tracked 147 single-nucleotide polymorphisms (SNPs), places where the genetic code differs by one letter in different people. Searching for SNPs that tend to have one "spelling" in people with reading impairments and another spelling in normal readers, the researchers found that a disproportionate number of such SNPs showed up in a gene called DCDC2. © 2005 by the American Association for the Advancement of Science.
Scientists have homed in on a gene that might be involved in dyslexia, a condition that causes difficulty with reading and spelling. The gene has appeared as a suspect before, and researchers hope that the new findings will help them better understand what happens in the brains of people with this condition, as well as provide insights into the workings of language. Dyslexia afflicts up to 10% of the population, and although those individuals have trouble with reading and spelling, they often have normal or even above-average intelligence. They also use slightly different parts of their brains than the average person does when reading and writing. The condition seems to be at least partly inherited, but it has been a challenge to find any of the genes involved, which are most likely scattered across several chromosomes. Now, researchers believe that they are one step closer to fingering a possible culprit. Natalie Cope and Julie Williams of Cardiff University in the United Kingdom and their colleagues studied 223 people with dyslexia, as well as their families and 273 controls. The team reports in the current issue of the American Journal of Human Genetics that those with dyslexia had a strong tendency to carry alterations in KIAA0319, a gene on chromosome 6p. Copyright © 2005 by the American Association for the Advancement of Science.
Dyslexia can impair a driver's reactions as much as a moderate drinking session. That is the conclusion of a small study which compared how quickly dyslexic and non-dyslexic drivers react to traffic signs. Those with dyslexia, which is characterised by difficulties with reading and writing, took on average 30% longer to react. The controversial finding will raise questions about whether people with dyslexia should have extra tests before being allowed behind the wheel. Drivers just over the UK's alcohol limit, which can be exceeded by drinking two pints of beer, are typically 10% slower than normal to react. In the study, Hermundur Sigmundsson at the Norwegian University of Science and Technology in Trondheim gave 17 volunteers, six of whom were dyslexic, two different tests. The first involved a 4-minute drive along a simulated country road at 50 to 80 kilometres per hour. In the second task, the volunteers drove through a city at lower speeds for 10 minutes. The simulator flashed up traffic signs in the drivers' field of view and measured how quickly they responded by pushing a button or saying "now". In the rural drive, the signs appeared directly ahead, while in the city they appeared in a variety of places. © Copyright Reed Business Information Ltd.
Helen Pilcher There is no one cause for dyslexia: rather, the causes vary between languages. So conclude researchers who have found that Chinese children with reading difficulties have different brain anomalies to their Western counterparts1. The finding explains why one can be dyslexic in one language but not another. The team also hopes the work will aid the design of culturally specific strategies for learning to read and write that could benefit everyone. People with dyslexia often find it difficult to recognize and understand words. Speakers of alphabetic languages, such as English or Russian, can have a problem converting letters into sounds. Dyslexics in these languages have reduced activity in a brain region called the left temporoparietal cortex. But Chinese readers must learn the meanings of around 5,000 different characters, each corresponding to a word. Instead of letter-to-sound conversion problems, Chinese dyslexics have difficulties extrapolating from a symbol's shape to its sound and meaning. ©2004 Nature Publishing Group
By JOSEPH B. VERRENGIA With 6,000 characters to memorize, Westerners shudder at the idea reading even the most basic street signs and instructions in Chinese. A new set of brain images shows why: Reading English-style alphabets and Chinese characters use very different parts of the brain. The results also suggest that Chinese schoolchildren with reading problems misfire in a different brain region than the one used in reading alphabet-based languages like English. This demonstrates that the learning disorder dyslexia is not the same in every culture and does not have a universal biological cause, researchers said. An image taken from TV shows a soldier rushing a girl away from the school in Beslan, in the region of North Ossetia. The guerrillas attacked on the first day of the school year. (Reuters Television) Neurologists described the results as "very important and innovative." While dyslexia has certain common roots, they said they now have some proof that this kind of functional problem plays out differently according to the unique demands that Western and Eastern languages place on the brain's wiring and processing centers. © 2004 The Associated Press
Bruce Bower A new brain-imaging study indicates that a specially designed program for second and third graders deficient in reading boosts their reading skills while prodding their brains to respond to written material in the same way that the brains of good readers do. The same investigation found that the remedial instruction typically offered to poor readers in the nation's schools doesn't improve their skills and fails to ignite activity in brain areas that have been linked to effective reading. "Good teaching can change the brain in a way that has the potential to benefit struggling readers," says pediatrician Sally Shaywitz of Yale University School of Medicine. At least one in five U.S. grade-schoolers with average or above-average intelligence encounters severe difficulties in learning to read, researchers estimate. In 2000, a panel of educators and scientists convened by Congress concluded that reading disability stems primarily from difficulties in recognizing the correspondence between speech sounds and letters. Copyright ©2004 Science Service.
Related chapters from BP7e: Chapter 19: Language and Hemispheric Asymmetry; Chapter 7: Life-Span Development of the Brain and Behavior
Related chapters from MM:Chapter 15: Language and Our Divided Brain; Chapter 13: Memory, Learning, and Development
Link ID: 5428 - Posted: 06.24.2010
Bruce Bower For the first time, scientists have identified a gene that appears to influence the development of at least some cases of dyslexia. This learning disorder is characterized by difficulties in perceiving sounds within words, spelling and reading problems, and troubles with written and oral expression. It's estimated that dyslexia affects at least 1 in 25 people. Although scientists are investigating dyslexia's suspected neural roots (SN: 5/24/03, p. 324: http://www.sciencenews.org/20030524/fob4.asp), the condition's causes remain unknown. If confirmed in further studies, the new genetic finding represents a major step forward for dyslexia researchers. Until now, investigators have only been able to link dyslexia to alterations along stretches of DNA containing tens or hundreds of genes. The most prominent of these genetic segments are located on chromosomes 6 and 15. Copyright ©2003 Science Service.
For the 10 to 15 percent of school-aged children in the U.S. who suffer from dyslexia, the written word often feels like an insurmountable obstacle. But a spate of research is helping scientists get to the root of the condition and suggest new methods of treatment. Research published today in the journal Neurology suggests that some therapies can make a difference quickly. Scientists report that dyslexic children showed normal brain activation patterns during reading tests after just three weeks of specialized instruction. Elizabeth Aylward of the University of Washington and her colleagues tested 10 children who suffered from dyslexia and scored 30 percent below average on standardized reading tests despite having above average intelligence and 11 children classified as good readers. © 1996-2003 Scientific American, Inc.
Gene hint to human reading ability. HELEN PEARSON A Finnish family has given the first clear clue to a gene involved in dyslexia. Between 5 and 15% of people are dyslexic. They have problems reading, writing and spelling. Although scientists have suspected that genes are involved, they had not come up with a convincing candidate - until now. One gene is mutated in around 10% of Finnish dyslexics, compared with 2-3% in the rest of the population, Juha Kere of the University of Helsinki, Finland and his team found. "If you have the gene you become more susceptible, but you're not necessarily dyslexic," he says. © Nature News Service / Macmillan Magazines Ltd 2003
BY ROBYN SURIANO The Orlando Sentinel - Mariel Segovia changes from her stylish denim jacket and black jeans into drab, green hospital scrubs and climbs onto a table for a brain scan. The Neuroimaging machine is pulled into place, swallowing most of the 10-year-old's head like a giant helmet. The $1.8 million device is so sensitive that the metal buttons on Mariel's jeans would disrupt the machine. Any body movement - even blinking - is also bad for the machine. So Mariel is lying still with her hands clasped on her chest, eyes focused on a computerlike screen hanging above her. This is not a medical test, and Mariel is not a patient. The healthy fifth-grader with a sister, brother and a trampoline at her Texas home is helping research that could revolutionize the way reading is taught in America. © 2002, The Orlando Sentinel (Fla.).
Copyright © 2002 AP Online The Associated Press - Scientists have found new evidence linking the reading problem called dyslexia to glitches in a particular region of the brain. The evidence comes from brain scans of 70 dyslexic and 74 non-impaired children, ages 7 to 18. It follows a 1998 brain scan study that reported the link in adults. The new work, by including children as young as 7, shows the brain problem is present at the beginning of reading ability, said researcher Sally Shaywitz of Yale University. Copyright © 2001 Nando Media
Missile-tracking technology may spot symptoms of learning impairment. VIRGINIA GEWIN Eye-tracking glasses developed to reduce fighter pilots' workload by enabling their eyes to direct weapons could help to diagnose dyslexia. Qinetiq, part of the British government's former Defence Evaluation and Research Agency, has just received a grant to create child-size prototype glasses. Some scientists think that eye movements offer clues as to why dyslexics struggle to read and write. Dyslexia affects between five and ten per cent of the world's population. "Many of the problems are due to failure of the eyes to remain steady when they're trying to take in the visual form of words," says dyslexia researcher John Stein of the University of Oxford, who is working with Qinetiq. Until now, he says, "we've lacked a means of measuring eye movements accurately". © Nature News Service / Macmillan Magazines Ltd 2002
FORTUNE examines business leaders and artists who have gone beyond the limitations of dyslexia. By Betsy Morris Consider the following four dead-end kids. One was spanked by his teachers for bad grades and a poor attitude. He dropped out of school at 16. Another failed remedial English and came perilously close to flunking out of college. The third feared he'd never make it through school--and might not have without a tutor. The last finally learned to read in third grade, devouring Marvel comics, whose pictures provided clues to help him untangle the words. These four losers are, respectively, Richard Branson, Charles Schwab, John Chambers, and David Boies. Billionaire Branson developed one of Britain's top brands with Virgin Records and Virgin Atlantic Airways. Schwab virtually created the discount brokerage business. Chambers is CEO of Cisco. Boies is a celebrated trial attorney, best known as the guy who beat Microsoft. © Copyright 2002 Time Inc. All rights reserved.
A 10-minute screening test to identify pre-school children who might be dyslexic has been developed by language experts at University College London. The test will be used by children from the age of three and a half upwards, says Professor Heather van der Lely. But Dr John Rack of Dyslexia Action urged caution about the risk of "false alarms" from short screening tests. Dyslexia is a condition that can cause difficulty with reading, writing and spelling. The test has been developed by Professor van der Lely, who is director of the UCL Centre for Developmental Language Disorders and Cognitive Neuroscience. What makes this test different is that it can be carried out in only 10 minutes - and that it can be used before children are usually able to read, picking up any potential concerns before children have started full-time education. Professor van der Lely, speaking on BBC Radio 4's Today programme, said that the test, which asks a child to repeat sentences and re-tell a story, can help with early intervention. (C)BBC
The dyslexic brain struggles to read because even small distractions can throw it off, according to a new model of dyslexia emerging from a group of recent studies. The studies contradict an influential, 30-year-old theory that blamed dyslexia on a neural deficit in processing the fast sounds of language. Instead, the studies suggest that children with dyslexia have bad filters for irrelevant data. As a result, they struggle to form solid mental categories for identifying letters and word sounds. Such children may benefit from intensive training under "noisy" conditions to strengthen their mental templates, said University of Southern California neuroscientist Zhong-Lin Lu. Lu was a co-author on three studies, along with lead author and former USC graduate student Anne Sperling (now at the National Institute of Mental Health), USC psychologist Franklin Manis and University of Wisconsin, Madison psychologist Mark Seidenberg. The most recent study is due to be published later this month in Psychological Science. Confusion about dyslexia rivals the confusion of dyslexia. Many still think that to have dyslexia means to mix up your letters (one of many possible symptoms having to do with word recognition, directional ability and decoding of symbols).
Brain images of children with dyslexia taken before they received spelling instruction show that they have different patterns of neural activity than do good spellers when doing language tasks related to spelling. But after specialized treatment emphasizing the letters in words, they showed similar patterns of brain activity. These findings are important because they show the human brain can change and normalize in response to spelling instruction, even in dyslexia, the most common learning disability. The research is unique in that it looks at images of individual brains rather than the composite group images, or maps, that are typically produced to show which areas of the brain are activated when people are engaged in specific tasks. Being able to study how individual brains differ between good and poor spellers and how they normalize after receiving one of two treatments is an important advance, according to University of Washington neuroimaging scientist Todd Richards and neuropsychologist Virginia Berninger, who headed the research team. The new findings were published in the January issue of the journal Neurolinguistics. "Most people think dyslexia is a reading disorder, but it is also a spelling and writing problem," said Berninger, who directs the UW's Learning Disabilities Center. "Our results show that all dyslexics in the 9- to 12-year-old range have spelling problems and children who cannot spell cannot express their ideas in writing."
By SANDRA BLAKESLEE One year after scientists discovered a gene whose flaw contributes to dyslexia, two more such genes have now been identified. The findings, described yesterday in Salt Lake City at a meeting of the American Society of Human Genetics, support the idea that many people deemed simply lazy or stupid because of their severe reading problems may instead have a genetic disorder that interfered with the wiring of their brains before birth. "I am ecstatic about this research," said Dr. Albert M. Galaburda of Harvard Medical School, a leading authority on developmental disorders who was not involved in the latest discoveries. The findings, added to last year's, mean that for the first time, "we have a link between genes, brain development and a complex behavioral syndrome," Dr. Galaburda said. As many as a dozen genes are probably involved in the disorder, he said, with each playing a role in the necessary migration of neurons as the brain's circuitry develops. Researchers said a genetic test for dyslexia should be available within a year or less. Children in families that have a history of the disorder could then be tested, with a cheek swab, before they are exposed to reading instruction. If children carry a genetic risk, they could be placed in early intervention programs. Copyright 2005 The New York Times Company
Pediatric researchers at Yale School of Medicine have identified a gene on human chromosome 6 called DCDC2, which is linked to dyslexia, a reading disability affecting millions of children and adults. The researchers also found that a genetic alteration in DCDC2 leads to a disruption in the formation of brain circuits that make it possible to read. This genetic alteration is transmitted within families. "These promising results now have the potential to lead to improved diagnostic methods to identify dyslexia and deepens understanding of how the reading process works on a molecular level," said lead author Jeffrey R. Gruen, M.D., associate professor in the Pediatrics Department at Yale School of Medicine. The study will be published in a special issue of Proceedings of the National Academy of Sciences on October 28. Gruen and first author Haiying Meng will also present the findings that same day at the American Society of Human Genetics (ASHG) meeting in Salt Lake City, Utah. Gruen and co-authors used a statistical approach to study and compare specific DNA markers in 153 dyslexic families. "We now have strong statistical evidence that a large number of dyslexic cases--perhaps as many as 20 percent--are due to the DCDC2 gene," said Gruen. "The genetic alteration on this chromosome is a large deletion of a regulatory region. The gene itself is expressed in reading centers of the brain where it modulates migration of neurons. This very architecture of the brain circuitry is necessary for normal reading."
An education professor has cast doubt on the scientific validity of the term 'dyslexia', saying experts cannot agree on what it is or how to treat it. Writing in the Times Educational Supplement, Julian Elliott said it was largely an "emotional construct". The Durham University professor questions the scientific validity of the term 'dyslexia', saying diagnosis does not lead to particular treatment. The British Dyslexia Association says the claims are inflammatory. Professor Elliott, a psychologist, said his argument was based on "an exhaustive review of the research literature". After 30 years in the field, he said, he had little confidence in his ability to diagnose dyslexia. Professor Elliott told the BBC News website: "There is no consensus as to what it is and how to diagnose it. People describe all sorts of symptoms as dyslexia. And if you do diagnose it, it does not point to any intervention in particular. "It's one of those terms that is like the Cheshire Cat - if it does exist, we don't know what to do about it." He said, contrary to talk of 'miracle cures', there was no sound, widely-accepted body of scientific work that had shown that any particular teaching approach was more appropriate for 'dyslexic' children than for other poor readers". Dyslexia is defined by BBC health expert Dr Rob Hicks as "a congenital and developmental condition that causes neurological anomalies in the brain. (C)BBC
The dyslexic brain may have a general problem forming perceptual categories, including the templates for printed letters and speech sounds, say USC neuroscientists. This is reflected in a reduced ability to filter out visual "noise" that can obscure a pattern, the researchers suggest. Their novel hypothesis, published in the current issue of Nature Neuroscience, raises broader questions: Does the dyslexic brain's trouble with patterns and noise extend to other senses? Does poor filtering inhibit the formation of perceptual categories? Or is poor formation of categories the root cause of dyslexics' problem with noise? Dyslexia is the most common and perhaps least understood reading disability. Affecting millions of Americans, it has a history of uncertain explanations. An old, discredited, but persistent view is that dyslexics jumble their letters. In the 1980s, the subtler "magnocellular hypothesis" gained favor with some scientists. Named for a type of neuron, the hypothesis held that dyslexics struggle to process rapid visual signals. Language comprehension also requires rapid processing ability. The Nature Neuroscience study casts doubt on the magnocellular hypothesis. The lead author was Anne Sperling, a graduate of USC's neuroscience program whose Ph.D. thesis was based on the study. The research team, which included Zhong-Lin Lu and Franklin Manis, professors of psychology in the USC College of Letters, Arts and Sciences, and Mark Seidenberg of the University of Wisconsin, Madison, asked dyslexic and non- dyslexic children to identify patterns presented with and without visual noise.