Links for Keyword: Dyslexia
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Researchers trying to tease out the genetic basis of dyslexia have discovered a location on chromosome 2 that may contain one or more genes that contribute to the reading disorder and make it difficult for people to rapidly pronounce pseudowords. The team from the University of Washington, headed by medical geneticists Dr. Wendy Raskind and Ellen Wijsman and developmental psychologist Virginia Berninger, cautioned that the new findings do not mean that scientists have found "the gene" responsible for dyslexia. "Just as with heart disease, no single gene will provide the answer to what causes dyslexia," said Raskind. "When you look at something that is inherited there could be multiple genes, perhaps as many as a hundred, that contribute to it. And when you look at any characteristic of a person, you must consider the environmental background. There are other factors besides genes that could modify a behavior." The study, published in the March issue of the journal Molecular Psychiatry, is noteworthy for two reasons. First, it points to a new location containing genes that contribute to dyslexia. Second, the gene or genes at that location are involved in speed of decoding – changing written words into spoken words without clues to their meaning – a basic and persistent component of dyslexia.
Reading is something most of us take for granted. But many people struggle everyday of their lives to read and understand simple words and phrases. "I avoided reading because I would have to read a sentence over and over and still not understand what I read," explains Dee Register from Kernersville, North Carolina, who wasn't diagnosed with dyslexia until she was in her early 40's. If left untreated, childhood dyslexia becomes an adult problem. "It's not something that's outgrown," says neurophysiologist Lynn Flowers from Wake Forest University Baptist Medical Center. "Ten percent of the child – and therefore the adult – population is affected by dyslexia to some degree," she says. "It isn't an all or nothing kind of disorder, it comes in shades as well." Dyslexia is a language-based learning disability that tends to run in families. "People without dyslexia process information in certain ways, in certain brain systems and certain neural pathways, and dyslexics do it differently and less efficiently," explains Judith Birsh, President of the New York branch of the International Dyslexia Association. People who suffer from dyslexia find it difficult to sort out the sounds within words, which make reading, writing and spelling very difficult. "If you’re stuck at the word-reading level and you’re laboring intensively over decoding [sounds], then you have nothing much left to work on comprehension and certainly you’re not going to speed along because you’re struggling along decoding the individual words," says Birsh. It can also have an affect on other aspects of a person's life such as short-term memory, mathematics and concentration. © ScienCentral, 2000-2005.
Washington, DC – New findings from researchers at Georgetown University Medical Center in collaboration with Wake Forest University School of Medicine have shown that there is hope for individuals suffering a life-long history of reading problems. Using brain imaging technology the research group showed how the adult dyslexic brain responds to a specific phonological-based reading intervention program responsible for reading skill improvement. Published in the October 28 issue of the Journal Neuron, this is the first research study to examine the brain systems related to successful phonological-based instruction in dyslexic adults. "Reading is one of the most important skills we learn – it affects virtually every aspect of a person's life," said Dr. Guinevere Eden, associate professor of pediatrics, director of Georgetown University's Center for the Study of Learning, and lead author of the study. "Despite the fact that the majority of individuals with dyslexia are adults, little is known about the biological basis of how they can improve their reading skills. We need to understand the neural mechanisms behind these research-based reading instructions so that we can achieve a deeper understanding of precisely how these interventions work. Our findings suggest that the brain mechanisms used by adult dyslexics might be different from those observed when young children undergo remediation, a strong indication that there will never be a 'one size fits all' approach to helping dyslexics become proficient readers."
ST. PAUL, Minn. – Researchers in Italy have observed significant reductions of gray matter volume in areas of the brain associated with language processing among people with a family history of dyslexia in comparison with controls with no reading problems. Published in the August 24 issue of Neurology, the scientific journal of the American Academy of Neurology, the study also lends support to previous studies suggesting intensive reading therapy activates areas of the brain necessary for word de-coding. The study of 10 people with familial dyslexia and 11 controls was the first to employ an advanced testing method – voxel-based morphometry (VBM) – which allows more in-depth detection and measurement of gray-white tissue volume and density differences than other testing tools, including magnetic resonance imaging, or MRI. The brain is made up of gray matter, where the brain cells reside, and white matter, where the nerve tracts that allow connections between different parts of the brain and spinal cord reside. The study also was the first to account for variabilities in whole brain volume, age of the subjects and differences in brain shape. Each of the subjects with dyslexia had at least one close relative with either clinically evident dyslexia or a long history of reading problems.
CHICAGO – Sights and sounds cross paths abnormally in the minds of dyslexic readers, according to the first functional magnetic resonance imaging (fMRI) study of multisensory processing in people with the disorder. "Dyslexic readers appear to process auditory and visual sensory cues differently than do normal readers, and these differences may be the cause of their difficulty in reading," said the study's lead author, Jonathan H. Burdette, M.D., assistant professor of neuroradiology and associate in the department of bioengineering at Wake Forest University in Winston-Salem, N.C. Dr. Burdette presented his research today at the 89th Scientific Assembly and Annual Meeting of the Radiological Society of North America (RSNA). Dyslexia is a learning disability characterized by difficulty with word recognition. Up to 8 percent of American elementary school children may have the reading disorder, according to the National Institute of Mental Health. While the underlying neurological basis for dyslexia is still unclear, previous studies have shown that people with dyslexia cannot distinguish the sounds in spoken words. However, reading is a complex mental task, requiring a series of interactions among areas of the brain that control auditory, visual, language and memory processing.
Imaging studies yield a potential core marker for reading problems, underscore neurological basis of difficulties WASHINGTON — Researchers have additional evidence that reading problems are linked to abnormal sound processing, thanks to high-precision pictures of the brain at work. In a recent study, when children without reading problems tried to distinguish between similar spoken syllables, speech areas in the left brain worked much harder than corresponding areas in the right brain, whose function is still unknown. But when children with dyslexia made the same attempt, those right-brain areas actually worked harder, going into overdrive after a brief delay. These findings appear in the October issue of Neuropsychology, which is published by the American Psychological Association (APA). Psychologists at The University of Texas Health Science Center at Houston targeted the suspect brain areas by isolating speech-processing sites from sites involved with other aspects of language, such as memory and meaning. As a result, they believe their research contributes to the identification of a central marker of the deficit that makes it hard for people with dyslexia to process similar but different sounds –- in both spoken and written form. The results parallel prior evidence gathered by the Houston team that brains of children with dyslexia also respond abnormally during reading. The researchers studied the brain activity of 12 children with and 11 children without dyslexia during a simple speech perception task. The children were eight to 12 years old. Magnetoencephalography (MEG), a non-invasive, high-resolution form of functional imaging, highlighted precise activity in participants’ left and right temporoparietal (TP) language areas while the children discriminated between spoken pairs of syllables, such as /ga/ and /ka/. This kind of task, known as phonological processing, is fundamental to acquiring reading skill. The temporoparietal areas are on the surface in the back of the brain. © 2003 American Psychological Association
St. Paul, MN –After only three weeks of reading instruction, brain scans in children with dyslexia develop activation patterns that match those of normal readers, according to a new study published in the July 22 issue of Neurology, the scientific journal of the American Academy of Neurology. These findings indicate that children with dyslexia use the same regions of their brains as other readers, and that specialized instruction can rapidly compensate for some types of reading deficits. Dyslexic children in this study had above average intelligence but scored approximately 30 percent lower than average on standard reading tests. The dyslexic children and a group of good readers of the same age underwent functional magnetic resonance imaging (fMRI) to map their brain activation patterns during two types of reading tests. The children with dyslexia then received a three-week training program based on principles outlined by the National Reading Panel (www.nationalreadingpanel.org), convened by the National Institute of Child Health and Human Development. Both groups of children then underwent a second brain scan. The experiment was conducted during the summer, to avoid confounding effects from school instruction.
Was Orton right? Washington, DC – Using functional magnetic resonance imaging (fMRI) to study brain activity in children, researchers today confirmed part of an eighty-year-old theory on the neurobiological basis of reading disability, and shed new light on brain regions that change as children become accomplished readers. Their findings were reported in the May 18 online publication of the journal Nature Neuroscience. In 1925 Dr. Samuel Orton, a clinician and prominent dyslexia researcher, hypothesized that normally developing readers suppress the visual images reported by the right hemisphere of the brain because these images could potentially interfere with input from the left. Advanced technology allowed researchers at Georgetown University Medical Center to discover that children do in fact "turn off" the right side of the visual parts of the brain as they become accomplished readers. This confirms an aspect of Orton's theory--born out of observations of individuals with reading disability--is correct. For the first time, they also were able to demonstrate that different phonological skills relate to activity in different parts of the brain when children read. Phonological skills allow readers to sound out words by correctly associating sounds with written symbols. They are critical for children learning to read and are often found to be impaired in children with developmental dyslexia.
(NEWARK) – In a scientific first, researchers have shown that the brains of dyslexic children can be “rewired” through intensive remedial training to function more like those found in normal readers. Paula Tallal, Board of Governors Professor of Neuroscience at Rutgers-Newark, and other members of a multi-university research team used brain-imaging scans of dyslexic children to demonstrate that areas of the brain critical to reading skills became activated for the first time and began to function more normally after only eight weeks of special training. In addition, other regions of the brain also lit up on the functional magnetic resonance imaging (fMRI) scans in a compensatory process that the dyslexics may have used as they learned to read more fluently. The researchers’ groundbreaking findings were published Feb. 24 by the Proceedings of the National Academy of Sciences Early Edition. The other authors include faculty from Stanford and Cornell universities, the University of California’s Los Angeles and San Francisco campuses, and one of the co-founders of Oakland-based Scientific Learning Corporation. © 2001, Rutgers, The State University of New Jersey.
By REUTERS WASHINGTON, — American Indians and Alaska natives are more likely to smoke than any other group in the United States, with 40 percent of adults defined as smokers, the Centers for Disease Control and Prevention said this week. People of Chinese descent were the least likely to smoke, with just 12 percent reporting that they had smoked a cigarette in the past month, said the agency survey, which was released on Thursday. The survey of 74,000 youths ages 12 to 17 and 133,000 adults is the agency's first detailed statistical breakdown by ethnicity of who smokes and who does not, said a spokesman, Joel London. Copyright 2004 The New York Times Company
Related chapters from BP7e: Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Related chapters from MM:Chapter 4: The Chemistry of Behavior: Neurotransmitters and Neuropharmacology
Link ID: 4900 - Posted: 06.24.2010
By Bruce Bower A gene variant involved in brain development may contribute to reading problems, including dyslexia. Unlike speaking, reading is a thoroughly unnatural act. That doesn’t mean that biology has no role in literacy. A gene involved in early brain development influences a range of reading problems, including dyslexia, a new study published online October 1 in the American Journal of Psychiatry suggests. British children ages 7 to 9 who inherited a particular genetic sequence on chromosome 6 tended to perform poorly on tests of reading and spelling abilities, whether or not they had already been classified as dyslexic, say geneticist Silvia Paracchini of the University of Oxford in England and her colleagues. On average, carriers of the key genetic sequence scored as well on IQ tests as other kids did. In an earlier report, the scientists found that the DNA sequence spans part of a gene called KIAA0319 and is linked to dyslexia in children in England and the United States. Paracchini’s group has also shown that the chromosome 6 sequence often accompanies a reduced ability of the KIAA0319 gene to direct the prenatal migration of brain cells to appropriate destinations. Decreased protein production by KIAA0319 prompts subtle brain changes, beginning before birth, that contribute to reading problems, including dyslexia, the researchers propose. © Society for Science & the Public 2000 - 2008
Using new software developed to investigate how the brains of dyslexic children are organized, University of Washington researchers have found that key areas for language and working memory involved in reading are connected differently in dyslexics than in children who are good readers and spellers. However, once the children with dyslexia received a three-week instructional program, their patterns of functional brain connectivity normalized and were similar to those of good readers when deciding if sounds went with groups of letters in words. “Some brain regions are too strongly connected functionally in children with dyslexia when they are deciding which sounds go with which letters,” said Todd Richards, a UW neuroimaging scientist and lead author of a study published in the current issue of the Journal of Neurolinguistics. “We had hints in previous studies that the ability to decode novel words improves when a specific brain region in the right hemisphere decreases in activation. This study suggests that the deactivation may result in a disconnection in time from the comparable region in the left hemisphere, which in turn leads to improved reading. Reading requires sequential as well as simultaneous processes.” Richards and co-author Virginia Berninger, a neuropsychologist, said temporal connectivity, or the ability of different parts of the brain to “talk” with each other at the same time or in sequence, is a key in overcoming dyslexia. Berninger, who directs the UW’s Learning Disabilities Center, compared dyslexia to an orchestra playing with an ineffective conductor who does not keep all the musicians playing in synchrony with each other.
LONDON By health-newswire.com reporters The effectiveness of a simple “breath test” that may be able to identify children with dyslexia and determine whether they are benefiting from treatment is to be studied by UK researchers. The breath test, developed by scientists from the University of Oxford, works by measuring biochemical imbalances in the body that are thought to underlie some behavioural and learning difficulties. The development of the test follows research by Dr Alexandra Richardson, of the university’s Department of Physiology, who found that some people with conditions such as dyslexia, dyspraxia and attention deficit/hyperactivity disorder can be treated with a simple nutritional supplement. © Health Media Group 2002 Terms and Conditions
By Katherine Harmon Chinese dyslexia may be much more complex than the English variety, according to a new paper published online today in Current Biology. English speakers who have developmental dyslexia usually don't have trouble recognizing letters visually, but rather just have a hard time connecting them to their sounds. What about languages based on full-word characters rather than sound-carrying letters? Researchers looking at the brains of dyslexic Chinese children have discovered that the disorder in that language often stems from two separate, independent problems: sound and visual perception. The pronunciation of detailed and complex Chinese characters must be memorized, rather than sounded out like words in alphabet-based languages. That requirement led researchers to suspect that disabilities in the visual realm might come into play in dyslexia in that language. "A fine-grained visuospatial analysis must be preformed by the visual system in order to activate the characters' phonological and semantic information," said lead author Wai Ting Siok of the University of Hong Kong, in a prepared statement. To see whether Chinese dyslexics had trouble comprehending visual details, researchers used functional magnetic resonance imaging (fMRI) to study the brains of 12 Chinese children with dyslexia. When asked to complete a task that involved visually judging size, the dyslexic children had less activation in an area of the brain that is charged with visual-spatial processing (the left intraparietal sulcus) than did Chinese children with normal reading levels. Previous research had also shown that the dyslexic group had weak activation in areas that process phonological information (the left middle frontal gyrus) when tested with a rhyming task. © 1996-2009 Scientific American Inc.
Randolph E. Schmid -- Dyslexia affects different parts of children's brains depending on whether they are raised reading English or Chinese. That finding, reported in Monday's online edition of Proceedings of the National Academy of Sciences, means that therapists may need to seek different methods of assisting dyslexic children from different cultures. "This finding was very surprising to us. We had not ever thought that dyslexics' brains are different for children who read in English and Chinese," said lead author Li-Hai Tan, a professor of linguistics and brain and cognitive sciences at the University of Hong Kong. "Our finding yields neurobiological clues to the cause of dyslexia." Millions of children worldwide are affected by dyslexia, a language-based learning disability that can include problems in reading, spelling, writing and pronouncing words. The International Dyslexia Association says there is no consensus on the exact number because not all children are screened, but estimates range from 8 percent to 15 percent of students. Reading an alphabetic language like English requires different skills than reading Chinese, which relies less on sound representation, instead using symbols to represent words. Past studies have suggested that the brain may use different networks of neurons in different languages, but none has suggested a difference in the structural parts of the brain involved, Tan explained. © 2008 Discovery Communications
Symptoms, like difficultly sounding out words, make dyslexia readily detectable. But the causes of the disability are still hard to pinpoint. "Why? What causes these otherwise very bright children to struggle to read?" asks pediatrician Sally Shaywitz, co-director of Yale University's Center for the Study of Learning and Attention, and the author of "Overcoming Dyslexia." "Dyslexia is an unexpected difficulty first in learning to read, and then in having to struggle to read," she explains. "That means the person who is dyslexic has all the factors present that say, 'This person should be a good reader. They're intelligent, they're motivated, and they've had good education. Yet they still struggle to read." If left untreated, childhood dyslexia becomes an adult problem. "It's not something that's outgrown," says neurophysiologist Lynn Flowers from Wake Forest University Baptist Medical Center. "Ten percent of the child and therefore the adult population is affected by dyslexia to some degree," she says. "It isn't an all or nothing kind of disorder, it comes in shades as well." © ScienCentral, 2000-2005.
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