Reading with the Right Hemisphere: Evidence from Developmental Deep Dyslexia
I shall present a case study of developmental deep dyslexia that shows clear evidence of right hemisphere activation during single word reading, as originally proposed by Coltheart (1980; 1983). PIP is a young women with Ehlers-Danlos Syndrome, a genetic disorder affecting connective tissue growth. She has no structural brain abnormalities (as evidenced by MRI) and above average intelligence (VIQ = 113, PIQ = 140), yet reads at the level of a 6-year-old. In oral reading PIP shows characteristics of deep dyslexia: she fails to read aloud nonwords, she shows significant effects of imageability in word reading and lexical decision, and when misreading she makes semantic errors (e.g., reading 'gender' as “sex”). In contrast to adult acquired cases, PIP reads some function words accurately. Functional neuro-imagining (fMRI) shows PIP activates similar left hemisphere areas as controls during all reading tasks. However, she shows significantly increased activation of the right hemisphere when reading words of high imageability and nonwords to which she makes highly imageable lexicalisations (e.g., roin as lion). PIP's reading profile can be explained within a dual-route framework in which sublexical processes have failed to develop and instead additional non-verbal right hemisphere processes are employed to support lexical access.