New findings from the United Kingdom add to recent evidence that dyslexia is rooted in the cerebellum rather than in the learning centers of the cerebral cortex that have been the target of most research.
In the May 15 Lancet, researchers at the University of Sheffield reported on positron emission tomography (PET) studies of six adults with dyslexia and six without the condition. The PET scans monitored brain activity as the subjects performed a sequence of new or already-learned finger movements. When learning the new movements, brain activity in adults with dyslexia was significantly less than in controls in the right cerebellar cortex. When performing the sequences they already knew, brain activity in the dyslexic adults was reduced from that of controls in the right cerebellar cortex and the left cingulate gyrus of the cerebral cortex.
Voelker R. Targeting the Root of Dyslexia. JAMA. 1999;281(22):2078. doi:10.1001/jama.281.22.2078-JWM90004-4-1