Organic basis for dyslexia - Max Planck Leipzig Research Study

Severe and persistent reading and spelling impairment linked with difficulties in processing speech sounds (developmental dyslexia) may be associated with under-action of an area of the brain.

Establishing an underlying organic basis for dyslexia has been a controversial area in recent years, but a team based at the Max Planck Institute Leipzig has used functional MRI scanning on dyslexic adults.

They found that there was a dysfunction in the auditory sensory thalamus, the medial geniculate body (MGB), while all other structures in the auditory pathway behaved comparably with those in control patients without dyslexia.

Furthermore, MGB activity correlated with dyslexia diagnostic scores, indicating that the task modulation of the MGB is critical for performance in dyslexics.

The authors of the research, published this week in the online Proceedings of the National Academy of Sciences of the US, suggest that 'deficits in dyslexia are associated with a failure of the neural mechanism that dynamically tunes the MGB according to predictions from cortical areas to optimise speech processing.'

This research may go some way in establishing an underlying neural framework for the various presentations of some forms of dyslexia.

Read the Abstract and get access to the full paper here; PNAS online 

Authors: Begoña Díaz, Florian Hintz, Stefan J. Kiebel and Katharina von Kriegstein

Dyslexia: The Role of Hearing and Auditory Processing

Doctors have known for years that those with dyslexia process information differently than others, like seeing words with transposed letters but there is mounting evidence that they might also hear language differently, as well.

“Any sort of language problem could very well have its roots in perception itself,” said Susan Nittrouer, Ph.D., of The Ohio State University Wexner Medical Center. “To many people, the solution seems to be, well, we will just train those with dyslexia how to recognize words correctly but the problem is really more fundamental than that.”

Nittrouer said she began to suspect the role hearing might play in dyslexia after nearly a decade-long study involving children who were born deaf or with profound hearing loss.

“We began following this group of over a hundred children, basically, since they were infants,” Nittrouer said.

All the children in the study got cochlear implants, which use microphones mounted just behind their ears, to capture and feed sound waves to nerves near the brain.

Through consistent testing, researchers found that the implants made a remarkable difference in terms of childrens’ ability to hear, but they’ve raised some intriguing questions as well.

“Cochlear implants have been able to help children who are deaf basically function as hearing children do,” said Nittrouer.

“However, once you begin to scratch the surface, you often find that children who have cochlear implants function similarly to how children who have dyslexia function.”

Nittrouer says that’s important because it points to the role of hearing in dyslexia. “Given that they look so much like children with dyslexia,” said Nittrouer, “we can really connect the dots between their perception, the kind of signal that they’re getting, and the sort of language problem that results.”

Even more encouraging, is that researchers say they spotted problems in these children long before they would have been obvious in dyslexic children who have normal hearing.

“We were able to identify these emerging problems in these children at kindergarten,” Nittrouer said. “If they didn’t have cochlear implants and weren’t in this project, in all likelihood, these problems learning to read would not have have shown up until they were in 3rd grade.”

Nittrouer says more research need to be done, but her findings could eventually lead to a new approach to dyslexia.

“We might be able to develop tests that could be administered earlier to predict who might be at risk for dyslexia,” she said.

“If, indeed, it turns out to be that these children have broader perceptual issues, then we need to begin to put together a broader intervention approach,” said Nittrouer, “one that does not involve just pulling the children out of the classroom for 20 minutes of tutoring a few times a week, but rather a program that involves all educators for the child’s entire day at school.”

¹What is Dyslexia?, National Center for Learning Disabilities, (citing the National Institute of Child and Human Development), June 2012.

Dyslexia: Is Signal Processing in the Brain the cause?

This figure compares the situation in the brain of dyslexics and the control group. 

The blue area depicts the auditory cortices and the green area represents the medial geniculate bodies.

MPI for Human Cognitive and Brain Sciences

To participate successfully in life, it is important to be able to read and write.

Nevertheless, many children and adults have difficulties in acquiring these skills and the reason is not always obvious.

They suffer from dyslexia which can have a variety of symptoms. Thanks to research carried out by Begoña Díaz and her colleagues at the Max Planck Institute for Human Cognitive and Brain Sciences in Leipzig, a major step forward has been made in understanding the cause of dyslexia.

The scientists have discovered an important neural mechanism underlying dyslexia and shown that many difficulties associated with dyslexia can potentially be traced back to a malfunction of the medial geniculate body in the thalamus.

The results provide an important basis for developing potential treatments. 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.

Those affected suffer from dyslexia their whole lives. However, there are also always cases where people can compensate for their dyslexia.

“This suggests that dyslexia can be treated. We are therefore trying to find the neural causes of this learning disability in order to create a basis for improved treatment options,” says Díaz.

Between five and ten percent of the world’s children suffer from dyslexia, yet very little is know about its causes.

Even though those affected do not lack intelligence or schooling, they have difficulties in reading, understanding and explaining individual words or entire texts.

The researchers showed that dyslexic adults have a malfunction in a structure that transfers auditory information from the ear to the cortex is a major cause of the impairment: 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,” says Díaz.

Read more at: medicalxpress.com

Crickets, Books, and Bach: Develop a Summer Listening Program

The importance of learning to listen

Listening is an engaging way to learn, a primary approach to developing or strengthening reading strategies, and, in some cases, a necessary means to access information and knowledge.

Listening media, such as audio books and text-to-speech, can be especially helpful to children with learning disabilities, such as those with dyslexia and attention deficit/hyperactivity disorder (ADHD) , who struggle with print-based learning, and central auditory processing disorder (CAPD), who may struggle to listen.

For such students well-chosen listening experiences can open up new vistas of learning, providing access to information and ideas previously 'hidden' in books and supporting the reading process itself.

Such opportunities provide a powerful supplement or alternative to a reading program focused around printed text.

Research has shown that combining reading and listening through the use of audio books or text-to-speech programs improves the literacy skills of struggling readers, including those with learning disabilities.

Reading comprehension, listening comprehension, phonological awareness and blending, and naming skills have shown to be improved with a combined reading-listening program.

Listening while reading helps children learn the patterns of language, the obvious 'code' of letters and words on the page as well as less obvious codes, such as tone, nuance, and implied meaning.

Brain imaging technologies show that when we listen, different parts of the brain are engaged than when we read—or even when we merely hear something.

Listening can provide whole levels of information that are essential to determining the value and validity of a source.

Teaching children to listen to tone of voice not only helps them develop reading skills but can help in the development of their social and conversational skills, too.

For more information, see Plato Revisited: Learning Through Listening in the Digital World by David Rose& Bridget Dalton, published by RFB&D.

Read more here: Crickets, Books, and Bach: Develop a Summer Listening Program | Reading Topics A-Z | Reading Rockets