Posts tagged dyslexia
Articles and news from the latest research reports.
Researchers unravel genetics of dyslexia and language impairment
A new study of the genetic origins of dyslexia and other learning disabilities could allow for earlier diagnoses and more successful interventions, according to researchers at Yale School of Medicine. Many students now are not diagnosed until high school, at which point treatments are less effective.
The study is published online and in the July print issue of the American Journal of Human Genetics. Senior author Dr. Jeffrey R. Gruen, professor of pediatrics, genetics, and investigative medicine at Yale, and colleagues analyzed data from more than 10,000 children born in 1991-1992 who were part of the Avon Longitudinal Study of Parents and Children (ALSPAC) conducted by investigators at the University of Bristol in the United Kingdom.
Gruen and his team used the ALSPAC data to unravel the genetic components of reading and verbal language. In the process, they identified genetic variants that can predispose children to dyslexia and language impairment, increasing the likelihood of earlier diagnosis and more effective interventions.
Dyslexia and language impairment are common learning disabilities that make reading and verbal language skills difficult. Both disorders have a substantial genetic component, but despite years of study, determining the root cause had been difficult.
In previous studies, Gruen and his team found that dopamine-related genes ANKK1 and DRD2 are involved in language processing. In further non-genetic studies, they found that prenatal exposure to nicotine has a strong negative affect on both reading and language processing. They had also previously found that a gene called DCDC2 was linked to dyslexia.
In this new study, Gruen and colleagues looked deeper within the DCDC2 gene to pinpoint the specific parts of the gene that are responsible for dyslexia and language impairment. They found that some variants of a gene regulator called READ1 (regulatory element associated with dyslexia1) within the DCDC2 gene are associated with problems in reading performance while other variants are strongly associated with problems in verbal language performance.
Gruen said these variants interact with a second dyslexia risk gene called KIAA0319. “When you have risk variants in both READ1 and KIAA0319, it can have a multiplier effect on measures of reading, language, and IQ,” he said. “People who have these variants have a substantially increased likelihood of developing dyslexia or language impairment.”
“These findings are helping us to identify the pathways for fluent reading, the components of those pathways; and how they interact,” said Gruen. “We now hope to be able to offer a pre-symptomatic diagnostic panel, so we can identify children at risk before they get into trouble at school. Almost three-quarters of these children will be reading at grade level if they get early intervention, and we know that intervention can have a positive lasting effect.”
Brain Imaging Study Eliminates Differences in Visual Function as a Cause of Dyslexia
A new brain imaging study of dyslexia shows that differences in the visual system do not cause the disorder, but instead are likely a consequence. The findings, published today in the journal Neuron, provide important insights into the cause of this common reading disorder and address a long-standing debate about the role of visual symptoms observed in developmental dyslexia.
Dyslexia is the most prevalent of all learning disabilities, affecting about 12 percent of the U.S. population. Beyond the primarily observed reading deficits, individuals with dyslexia often also exhibit subtle weaknesses in processing visual stimuli. Scientists have speculated whether these deficits represent the primary cause of dyslexia, with visual dysfunction directly impacting the ability to learn to read. The current study demonstrates that they do not.
“Our results do not discount the presence of this specific type of visual deficit,” says senior author Guinevere Eden, PhD, director for the Center for the Study of Learning at Georgetown University Medical Center (GUMC) and past-president of the International Dyslexia Association. “In fact our results confirm that differences do exist in the visual system of children with dyslexia, but these differences are the end-product of less reading, when compared with typical readers, and are not the cause of their struggles with reading.”
The current study follows a report published by Eden and colleagues in the journal Nature in 1996, the first study of dyslexia to employ functional Magnetic Resonance Imaging (fMRI). As in that study, the new study also shows less activity in a portion of the visual system that processes moving visual information in the dyslexics compared with typical readers of the same age.
This time, however, the research team also studied younger children without dyslexia, matched to the dyslexics on their reading level. “This group looked similar to the dyslexics in terms of brain activity, providing the first clue that the observed difference in the dyslexics relative to their peers may have more to do with reading ability than dyslexia per se,” Eden explains.
Next, the children with dyslexia received a reading intervention. Intensive tutoring of phonological and orthographic skills was provided, addressing the core deficit in dyslexia, which is widely believed to be a weakness in the phonological component of language. As expected, the children made significant gains in reading. In addition, activity in the visual system increased, suggesting it was mobilized by reading.
The researchers point out that these findings could have important implications for practice. “Early identification and treatment of dyslexia should not revolve around these deficits in visual processing,” says Olumide Olulade, PhD, the study’s lead author and post-doctoral fellow at GUMC. “While our study showed that there is a strong correlation between people’s reading ability and brain activity in the visual system, it does not mean that training the visual system will result in better reading. We think it is the other way around. Reading is a culturally imposed skill, and neuroscience research has shown that its acquisition results in a range of anatomical and functional changes in the brain.”
The researchers add that their research can be applied more broadly to other disorders. “Our study has important implications in understanding the etiology of dyslexia, but it also is relevant to other conditions where cause and consequence are difficult to pull apart because the brain changes in response to experience,” explains Eden.
(Source: explore.georgetown.edu)
Brain Anatomy of Dyslexia Is Not the Same in Men and Women, Boys and Girls
Using MRI, neuroscientists at Georgetown University Medical Center found significant differences in brain anatomy when comparing men and women with dyslexia to their non-dyslexic control groups, suggesting that the disorder may have a different brain-based manifestation based on sex.
Their study, investigating dyslexia in both males and females,is the first to directly compare brain anatomy of females with and without dyslexia (in children and adults). Their findings were published online in the journal Brain Structure and Function.
Because dyslexia is two to three times more prevalent in males compared with females, “females have been overlooked,” says senior author Guinevere Eden, PhD, director for the Center for the Study of Learning and past-president of the International Dyslexia Association.
“It has been assumed that results of studies conducted in men are generalizable to both sexes. But our research suggests that researchers need to tackle dyslexia in each sex separately to address questions about its origin and potentially, treatment,” Eden says.
Previous work outside of dyslexia demonstrates that male and female brains are different in general, adds the study’s lead author, Tanya Evans, PhD.
“There is sex-specific variance in brain anatomy and females tend to use both hemispheres for language tasks, while males just the left,” Evans says. “It is also known that sex hormones are related to brain anatomy and that female sex hormones such as estrogen can be protective after brain injury, suggesting another avenue that might lead to the sex-specific findings reported in this study.”
The study of 118 participants compared the brain structure of people with dyslexia to those without and was conducted separately in men, women, boys and girls. In the males, less gray matter volume is found in dyslexics in areas of the brain used to process language, consistent with previous work. In the females, less gray matter volume is found in dyslexics in areas involved in sensory and motor processing.
The results have important implications for understanding the origin of dyslexia and the relationship between language and sensory processing, says Evans.
Learning disabilities affect up to 10 percent of children
Up to 10 per cent of the population are affected by specific learning disabilities (SLDs), such as dyslexia, dyscalculia and autism, translating to 2 or 3 pupils in every classroom according to a new study.
The study – by academics at UCL and Goldsmiths - also indicates that children are frequently affected by more than one learning disability.
The research, published in Science, helps to clarify the underlying causes of learning disabilities and the best way to tailor individual teaching and learning for affected individuals and education professionals.
Specific learning disabilities arise from atypical brain development with complicated genetic and environmental causes, causing such conditions as dyslexia, dyscalculia, attention-deficit/hyperactivity disorder, autism spectrum disorder and specific language impairment.
While these conditions in isolation already provide a challenge for educators, an additional problem is that specific learning disabilities also co-occur for more often that would be expected. As, for example, in children with attention-deficit/hyperactivity disorder, 33 to 45 per cent also suffer from dyslexia and 11 per cent from dyscalculia.
Lead author Professor Brian Butterworth (UCL Institute of Cognitive Neuroscience) said: “We now know that there are many disorders of neurological development that can give rise to learning disabilities, even in children of normal or even high intelligence, and that crucially these disabilities can also co-occur far more often that you’d expect based on their prevalence.
"We are also finally beginning to find effective ways to help learners with one or more SLDs, and although the majority of learners can usually adapt to the one-size-fits-all approach of whole class teaching, those with SLDs will need specialised support tailored to their unique combination of disabilities."
As part of the study, Professor Butterworth and Dr Yulia Kovas (Goldsmiths) have summarised what is currently known about SLD’s neural and genetic basis to help clarify what is causing these disabilities to develop, helping to improve teaching for individual learners, and also training for school psychologists, clinicians and teachers.
What the team hope is that by developing an understanding of how individual differences in brain development interact with formal education, and also adapting learning pathways to individual needs, those with specific learning disabilities will produce more tailored education for such learners.
Professor Butterworth said: “Each child has a unique cognitive and genetic profile, and the educational system should be able to monitor and adapt to the learner’s current repertoire of skills and knowledge.
"A promising approach involves the development of technology-enhanced learning applications – such as games - that are capable of adapting to individual needs for each of the basic disciplines."
(Source: eurekalert.org)
How can we stlil raed words wehn teh lettres are jmbuled up?
Researchers in the UK have taken an important step towards understanding how the human brain ‘decodes’ letters on a page to read a word. The work, funded by the Economic and Social Research Council (ESRC), will help psychologists unravel the subtle thinking mechanisms involved in reading, and could provide solutions for helping people who find it difficult to read, for example in conditions such as dyslexia.
In order to read successfully, readers need not only to identify the letters in words, but also to accurately code the positions of those letters, so that they can distinguish words like CAT and ACT. At the same time, however, it’s clear that raeders can dael wtih wodrs in wihch not all teh leettrs aer in thier corerct psotiions.
"How the brain can make sense of some jumbled sequences of letters but not others is a key question that psychologists need to answer to understand the code that the brain uses when reading," says Professor Colin Davis of Royal Holloway, University of London, who led the research.
For many years researchers have used a standard psychological test to try to work out which sequences of letters in a word are important cues that the brain uses, where jumbled words are flashed momentarily on a screen to see if they help the brain to recognise the properly spelt word.
But, this technique had limitations that made it impossible to probe more extreme rearrangements of sequences of letters. Professor Davis’s team used computer simulations to work out that a simple modification to the test would allow it to question these more complex changes to words. This increases the test’s sensitivity significantly and makes it far more valuable for comparing different coding theories.
"For example, if we take the word VACATION and change it to AVACITNO, previously the test would not tell us if the brain recognises it as VACATION because other words such as AVOCADO or AVIATION might start popping into the person’s head,” says Professor Davis. "With our modification we can show that indeed the brain does relate AVACITNO to VACATION, and this starts to give us much more of an insight into the nature of the code that the brain is using – something that was not possible with the existing test."
The modified test should allow researchers not only to crack the code that the brain uses to make sense of strings of letters, but also to examine differences between individuals – how a ‘good’ reader decodes letter sequences compared with someone who finds reading difficult.
"These kinds of methods can be very sensitive to individual differences in reading ability and we are starting to get a better idea of some of the issues that underpin people’s difficulty in reading," says Professor Davis. Ultimately, this could lead to new approaches to helping people to overcome reading problems.
(Source: esrc.ac.uk)
Action video games boost reading skills
Much to the chagrin of parents who think their kids should spend less time playing video games and more time studying, time spent playing action video games can actually make dyslexic children read better. In fact, 12 hours of video game play did more for reading skills than is normally achieved with a year of spontaneous reading development or demanding traditional reading treatments.
The evidence, appearing in the Cell Press journal Current Biology on February 28, follows from earlier work by the same team linking dyslexia to early problems with visual attention rather than language skills.
"Action video games enhance many aspects of visual attention, mainly improving the extraction of information from the environment," said Andrea Facoetti of the University of Padua and the Scientific Institute Medea of Bosisio Parini in Italy. "Dyslexic children learned to orient and focus their attention more efficiently to extract the relevant information of a written word more rapidly."
The findings come as further support for the notion that visual attention deficits are at the root of dyslexia, a condition that makes reading extremely difficult for one out of every ten children, Facoetti added. He emphasized that there is, as of now, no approved treatment for dyslexia that includes video games.
Facoetti’s team, including Sandro Franceschini, Simone Gori, Milena Ruffino, Simona Viola, and Massimo Molteni, tested the reading, phonological, and attentional skills of two groups of children with dyslexia before and after they played action or non-action video games for nine 80-minute sessions. The action video gamers were able to read faster without losing accuracy. They also showed gains in other tests of attention.
"These results are very important in order to understand the brain mechanisms underlying dyslexia, but they don’t put us in a position to recommend playing video games without any control or supervision," Facoetti said.
Still, there is great hope for early interventions that could be applied in low-resource settings. “Our study paves the way for new remediation programs, based on scientific results, that can reduce the dyslexia symptoms and even prevent dyslexia when applied to children at risk for dyslexia before they learn to read.”
And, guess what? Those kids will also be having fun.
Researchers discover a biological marker of dyslexia
Though learning to read proceeds smoothly for most children, as many as one in 10 is estimated to suffer from dyslexia, a constellation of impairments unrelated to intelligence, hearing or vision that make learning to read a struggle. Now, Northwestern University researchers report they have found a biological mechanism that appears to play an important role in the reading process.
"We discovered a systematic relationship between reading ability and the consistency with which the brain encodes sounds," says Nina Kraus, Hugh Knowles Professor of Neurobiology, Physiology and Communication. "Unstable Representation of Sound: A Biological Marker of Dyslexia," co-authored by Jane Hornickel, will appear in the Feb. 20 issue of The Journal of Neuroscience.
Recording the automatic brain wave responses of 100 school-aged children to speech sounds, the Northwestern researchers found that the very best readers encoded the sound most consistently while the poorest readers encoded it with the greatest inconsistency. Presumably, the brain’s response to sound stabilizes when children learn to successfully connect sounds with their meanings.
Happily biology is not destiny. In prior work in Northwestern’s Auditory Neuroscience Laboratory, Kraus and her colleagues found that the inconsistency with which the poorest readers encode sound could be “fixed” through training.
In that study, children with reading impairments were fitted for a year with assistive listening devices that transmitted their teacher’s voice directly into their ears. After a year, the children showed improvement not only in reading but also in the consistency with which their brains encoded speech sounds, particularly consonants.
"Use of the devices focused youngsters’ brains on the "meaningful" sounds coming from their teacher, diminishing other, extraneous distractions," said Kraus. "After a year of use, the students had honed their auditory systems and no longer required the assistive devices to keep their reading and encoding advantage."
People rarely have difficulty encoding vowel sounds, which are relatively simple and long, according to Kraus. It is consonant sounds — sounds which are shorter and more acoustically complex — that are most likely to be incorrectly categorized by the brain.
"Understanding the biological mechanisms of reading puts us in a better position to both understand how normal reading works and to ameliorate it where it goes awry," says Kraus.
"Our results suggest that good readers profit from a stable neural representation of sound, and that children with inconsistent neural responses are likely at a disadvantage when learning to read," Kraus adds. "The good news is that response consistency can be improved with auditory training."
Decades of research from laboratories worldwide have shown that reading ability is associated with auditory skills, including auditory memory and attention, the ability to rhyme sounds and the ability to categorize rapidly occurring sounds.
(Image: Michael Pettigrew)
A new font tailored for people afflicted with dyslexia is now available for use on mobile devices, thanks to a design by Abelardo Gonzalez, a mobile app designer from New Hampshire. Gonzalez, in collaboration with educators, has selected a font that many people with dyslexia find easier to read. Even better, the new font is free and has already been made available for some word processors and ebook readers. The font, called OpenDyslexic, has also been added to the font choices used by Instapaper—a program that allows users to copy a web page and save it to their hard drive.
Dyslexia Impairs Speech Recognition but Can Spare Phonological Competence
Dyslexia is associated with numerous deficits to speech processing. Accordingly, a large literature asserts that dyslexics manifest a phonological deficit. Few studies, however, have assessed the phonological grammar of dyslexics, and none has distinguished a phonological deficit from a phonetic impairment. Here, we show that these two sources can be dissociated. Three experiments demonstrate that a group of adult dyslexics studied here is impaired in phonetic discrimination (e.g., ba vs. pa), and their deficit compromises even the basic ability to identify acoustic stimuli as human speech. Remarkably, the ability of these individuals to generalize grammatical phonological rules is intact. Like typical readers, these Hebrew-speaking dyslexics identified ill-formed AAB stems (e.g., titug) as less wordlike than well-formed ABB controls (e.g., gitut), and both groups automatically extended this rule to nonspeech stimuli, irrespective of reading ability. The contrast between the phonetic and phonological capacities of these individuals demonstrates that the algebraic engine that generates phonological patterns is distinct from the phonetic interface that implements them. While dyslexia compromises the phonetic system, certain core aspects of the phonological grammar can be spared.
University of Tennessee Researchers Develop Comprehensive, Accessible Vision Testing Device
Eighty-five percent of children’s learning is related to vision. Yet in the United States, eighty percent of children have never had an eye exam or any vision screening before kindergarten, statistics say. When they do, the vision screenings they typically receive can detect only one or two conditions. Ying-Ling Chen, research assistant professor in physics at the University of Tennessee Space Institute in Tullahoma is working to change that with an invention that makes eye exams inexpensive, comprehensive, and simple to administer.