Dyslexia

Dyslexia: Major cause of learning difficulty may have been discovered by neuroscientists

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‘Adaptation is something the brain does to help make hard tasks easier [but] dyslexics are not getting this advantage’

Scientists have discovered what appears to be a fundamental reason why people are dyslexic.

Using MRI scans to monitor the brains of people who present with the condition, and those who don’t, researchers found a “really pronounced” difference in responses to a series of visual and audio cues.

The brains of people without dyslexia were more able to recognise repeated words or images in a process known as “neural adaptation”, while a “neural signature” was identified among dyslexics, whose brains displayed lower levels of “plasticity” – or response ability.

The researchers were surprised to find such a broad range of effects but speculated that dyslexia only shows itself when people try to read because this is a relatively demanding task.

While humans have evolved to be skilled verbal communicators, writing is a relatively recent occurrence in our history, particularly as something that most people in society do.

One of the researchers, Professor John Gabrieli, of the Massachusetts Institute of Technology, said: “You learn something upon the initial presentation that makes you better able to do it the second time, and the ease is marked by reduced neural activity. Because you’ve done something before, it’s easier to do it again.”

This website shows what it’s like trying to read with dyslexia

Scans of the brains of people with dyslexia showed this adaptation process was not as effective – their brains were more exercised to understand the same information, the academics reported in the journal Neuron.

Speaking to The Independent, Professor Gabrieli said: “There are different ways to struggle to read, but for many individuals with dyslexia, we suspect this might be the route pathway – the beginning would be this broader reduction in [brain] plasticity that only manifests itself when the demands for plasticity are highest.”

He added the study suggested a potential new way to alleviate effects of dyslexia by artificially increasing the plasticity of the brain.

 However Prof Gabrieli said the techniques used to do this – involving electromagnetic stimulation of the brain – were at an experimental stage and had not been tried for the condition.

“We’d love if it would have implications for helping people, but we know that’s far away,” he said.

Prof Tyler Perrachione, of Boston University – the lead author of the study – said: “Adaptation is something the brain does to help make hard tasks easier [but] dyslexics are not getting this advantage.

“I am surprised by the magnitude of the difference. In people without dyslexia, we always see adaptation, but in the dyslexics, the lack of adaptation was often really pronounced.”

About one in 10 people in the UK, some 6.3 million people, are estimated to have dyslexia.

In addition to making reading and spelling more difficult, it can affect short-term memory, maths and co-ordination. However it does not affect general intelligence or reasoning.

Dyslexia was first diagnosed in Seaford, Sussex, in 1896 as a “case of congenital word blindness” involving a 14-year-old boy called Percy.

A report in the British Medical Journal said that “in spite of this laborious and persistent training, he can only with difficulty spell out words of one syllable”.

“The schoolmaster who taught him for some years says that he would be the smartest lad in the school if the instruction were entirely oral,” it added.

However those with the condition were often dismissed as being “thick” or “lazy” and it was not until the 1970s that the role of language processing was recognised.

Professor Gabrieli said previous research had long laid that misconception to rest.

“I have colleagues who are professors who are dyslexic and who are amazing,” he said.

Dr John Rack, head of research at charity Dyslexia Action, said the researchers had come up with “some interesting findings”.

“What is particularly interesting is that better reading skills in adults and children with dyslexia were associated with greater repetition-induced neural adaptation,” he said.

“We also recognise that these results highlight a dysfunction of rapid neural adaptation as a core neurophysiological difference in dyslexia that may underlie impaired reading development and this new evidence is helping to build an understanding of the differences in brain functions which can ultimately result in a greater understanding of specific reading impairments.

“This is theoretically well-grounded research that is seeking to explain what we know to be the core issues for people with dyslexia: learning to map letters and sounds for the development of fluent reading and spelling skills. Increasing this understanding can help us to tailor our teaching interventions to be even more effective.”

Dyslexia can be overcome with nursery rhymes and music, says Cambridge professor .

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Children can overcome dyslexia by learning nursery rhymes, dancing and singing because the condition is caused by lack of rhythm in brain, a leading neuroscientists has suggested.

Exposing children to nursery rhymes and singing could help them overcome dyslexia, a Cambridge Professor has claimed

Usha Goswami, prof of Cognitive Developmental Neuroscience at Cambridge has spent the last 10 years testing the brains of youngsters to find out what was driving the learning problem.

She found that the dyslexia is not caused by children reading words incorrectly, but instead their inability to hear the rhythm of words when they are being spoken.

Brain scans shown that the metre of words was out of phase with internal rhythms in brain, meaning that youngsters struggled to encode the patterns, and therfore memorise speech.

But keeping up rhythmic practice will eventually allow children to read properly.

Children who are dyslexic could benefit from more rhythmic training

“Children who are dyslexic struggle with speech rhythm,” Prof Goswami told The Hay Festival.

“We realised that children are struggling in tasks which are not related to learning or reading but are related to rhythm.

“So we began to think that rhythm and these problems found in children with dyslexia might be related.”

Dyslexia is thought to be one of the most common learning difficulties. It’s estimated that up to 1 in every 10 people in the UK has a certain degree of dyslexia and Britain has one of the worst rates because the language is so difficult to learn.

Prof Goswami recommended clapping games, music, nursery rhymes and marching to The Grand Old Duke of York.

“All kinds of rhythmic experiences can be helpful, nursery rhymes, dancing and music as long as the beat is matched to language,” she said.

“Playground clapping and games may be very important to stopping dyslexia. You could start to remediate it before children even start school.

“If children keep it up they will learn to read. It will definitely happen. The brain just needs more training. These children need to know that their brain just works a bit differently and reading is going to be harder for them.”

Dyslexia caused by faulty signal processing in brain.

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Dyslexia, a learning disability can result when the medial geniculate nucleus in the thalamus of the brain does not process speech sounds correctly, a new study has claimed.

Researchers from Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig found that many difficulties associated with dyslexia can potentially be traced back to a malfunction of the medial geniculate nucleus in the thalamus.

The thalamus is a large, dual lobed mass of grey matter buried under the cerebral cortex. It is involved in sensory perception and regulation of motor functions.

There are three proposed cognitive subtypes of dyslexia: auditory, visual and attentional.

People who suffer from dyslexia have difficulties with identifying speech sounds in spoken language. For example, while most children are able to recognise whether two words rhyme even before they go to school, dyslexic children often cannot do this until late primary school age.

The research found that dyslexic adults have a malfunction in a structure that transfers auditory information from the ear to the cortex, the medial geniculate body in the auditory thalamus does not process speech sounds correctly.

“This malfunction at a low level of language processing could percolate through the entire system. This explains why the symptoms of dyslexia are so varied,” Begona Diaz from the Institute said.

The researchers conducted two experiments in which several volunteers had to perform various speech comprehension tasks.

When affected individuals performed tasks that required the recognition of speech sounds, as compared to recognise the voices that pronounced the same speech, magnetic resonance tomography (MRT) recordings showed abnormal responses in the area around the medial geniculate body.

In contrast, no differences were apparent between controls and dyslexic participants if the tasks involved only listening to the speech sounds without having to perform a specific task.

“The problem, therefore, has nothing to do with sensory processing itself, but with the processing involved in speech recognition,” Diaz said.

Source: the Hindu.

Keywords: dyslexia, faulty signal, brain function

Scientists Find Key Brain Differences in Dyslexia.

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The Brains of People With Dyslexia May Have Trouble Processing Sounds, Especially Speech

 

woman with hand to ear

There may be more to dyslexia than trouble with reading.

People with dyslexia sometimes see words and letters as scrambled, making reading a difficult task. Now a new study shows that dyslexia isn’t just a visual disturbance. It also appears to be a problem with the way the brain interprets sounds, particularly speech.

The study appears in the journal Neuron.

French researchers mapped the brain activity of 23 people with dyslexia and 21 people without the disorder as they listened to a white noise.

In order to understand the information in speech, the brain needs to be able to sync to the same frequency as the sounds it hears. The syncing of brain waves with sounds is called entrainment.

When the brain is properly entrained with a sound, it can correctly separate and interpret the signal, almost like breaking a code.

Researchers found that people without dyslexia had no trouble tuning their brains to the same frequencies as they heard in the white noise.

People with dyslexia, on the other hand, could not. Their brains had trouble syncing with sounds in the range of about 30 hertz, a frequency that’s important for understanding and decoding speech.

The dyslexic brain also appeared to be hyper-responsive to higher-frequency sounds.

This disrupted sound processing may help explain why people with dyslexia have trouble remembering and processing words and speech, says researcher Anne-Lise Giraud, a scientist with the Auditory Language Group at the Ecole Normale Superieure in Paris.

Study Signals ‘Progress’

Other experts who reviewed the study for WebMD said it offered important clues about the brain’s role in the often frustrating and debilitating condition.

“This is important information,” says Ken Pugh, PhD, who directs the Yale Reading Center in New Haven, Conn. “It’s progress.”

“This suggests a problem in the auditory cortex on the left side of the brain is making it difficult to perceive speech,” says Pugh, who is also the president and director of research at Yale’s Haskins Laboratories, which focuses on the biology of speech and language.

“That, in turn, might make it difficult to build an understanding of speech sounds that you need to have in order to learn to read,” he says.

source:webMD