Dyslexia findings could lead to new treatment
PEOPLE with dyslexia cannot read or spell properly due to communication problems in their brain – not because they fail to form mental images of the sounds that make up a language, as previously believed, scientists have found.
The findings could affect the way dyslexic children are trained to overcome their handicap, according to scientists, and could even lead to new treatments to prevent it.
Dyslexia has long been thought to result from an inability of the brain to learn all the small sound units, or "phonemes", used to build up words. But a study suggests that this is false, and that the real problem lies in one part of the brain not being able to link up with another, researchers said.
About one in 10 people suffers from dyslexia, which can lead to severe reading problems and difficulties with educational achievement, even in highly intelligent people.
Dyslexia is not associated with any obvious impairment in vision, hearing or general intelligence, and this has led some to suggest that "word blindness", as it is sometimes known, cannot be a genuine medical problem.
However, for about 40 years, neuroscientists have argued that the problem is real and lies with the brain's ability to acquire accurate representations of various phonemes – units of sound which help us to distinguish between one word and another.
More recently, other researchers have suggested that these phoneme representations are in fact there in the brain – it is just that they are not accessible by the other regions of the brain involved with language processing.
"The two hypotheses are very difficult to disentangle. This is because cognitive or behavioural tasks always tap both the representation and the access to this representation simultaneously," said Bart Boets, a clinical psychologist at the Catholic University of Leuven in Belgium.
Traditional educational techniques may have to be re-thought, as they are designed to improve the quality of phonetic representations, not to increase access to them, Dr Boets said. In the longer term, the results may also lead to new treatments based on improving these communication channels in the brain between various parts of the brain involved with the processing of language, he said.
The study, published in the journal 'Science', managed to separate the two competing theories by using real-time brain scanning, to observe how the brains of dyslexics and non-dyslexics coped with a set of mental tasks aimed at distinguishing between various sounds. The scientists found that the dyslexic group were just as accurate as the non-dyslexics in completing the tasks – and that the "crispness" of their brain scans were equal to or even better than the ones of those who could read normally. Dr Boets said the findings demonstrated that the phonetic representations of the dyslexic subjects were "perfectly intact".
However, the dyslexics were about 50pc slower than the normal readers in making their responses, suggesting a communication problem. (© Independent News Service)