Brain connections hampered in people with dyslexia

New research, from the University of Leuven in Belgium, suggests that problems with brain connectivity cause dyslexia.  The study, led by Bart Boets, a clinical psychologist, concluded that dyslexia is not caused by impairment in phonetic representations in the brain, but is caused by impairment in the brain's ability to access these phonetic representations.

These conclusions are important because many clinicians develop treatments for dyslexia based on the theory that dyslexia is caused by problems in the actual phonetic representations.  This new theory suggests that different types of treatment may be needed to help people with dyslexia.

"With this new knowledge, it is not unconceivable that we could design more focused and effective interventions that specifically target improving the specific connection between frontal and temporal language regions," Boets said.

Boets and his colleagues used functional magnetic resonance imaging (fMRI) to analyse the brains of 23 people with dyslexia as they listened to specific sounds. The study also included 22 people, who did not have dyslexia, as a control group.

In their analysis, the researchers used "multi-voxel activity analysis, or MVPA, to look at patterns of nerve activity in the brain as these individuals responded to certain speech stimuli, noting how accurately sounds were mapped to their related phonetic representations."

Through these techniques, they observed that the phonetic representations were "intact" or normal in the participants with dyslexia. The problem they observed was an impairment in the way the brain accessed the phonetic representations.

The study, Intact But Less Accessible Phonetic Representations in Adults with Dyslexia, is published in the journal Science.

©Mary M Conneely T/A Advocacy in Action