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 Bego-a D-az 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 D-az.
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 D-az.