Functional Neuroanatomy of Reading Remediation in Dyslexia

Abstract:
Although intensive phonological intervention is often successful in treating reading disability, the neural mechanisms responsible for the observed reading gains are poorly understood. We investigated behavioral and physiological changes resulting from a phonological intervention program (Lindamood-Bell) in twenty dyslexic adults with a lifelong history of dyslexia in two sessions separated by 10 weeks. Between sessions, ten individuals received Lindamood-Bell training on a daily basis for a total of eight weeks, while the other ten subjects received no intervention. The groups did not differ in reading measures prior to the intervention. After intervention, subjects in the intervention group showed improvement on tests of non-word reading, reading accuracy, and phonological awareness. Neural activity associated with phonological processing was identified with fMRI by contrasting sound deletion (deleting the first phoneme of an aurally presented word) to word repetition. An ANOVA modeling group and session effects revealed intervention related increases in task-related activity in the right occipito-temporal cortex, posterior parietal cortex, insula, primary motor cortex, inferior frontal gyrus, as well as left fusiform/lingual cortex and putamen. These findings demonstrate that reading gains in dyslexic adults are associated with compensatory engagement of right hemisphere perisylvian areas and the left fusiform/lingual gyrus.