A case of developmental deep dyslexia: What's left is right

Cases of acquired deep dyslexia have not clearly and consistently supported any of the theoretical models. We report on a case of a 51-year-old right-handed female, L. S., with a developmental history of deep dyslexia in order to test the neuropsychological models using a visual half-field semantic priming paradigm. Word targets were primed either by a highly associated word (e.g., CLEAN-DIRTY), a weakly associated word (e.g., CLEAN-TIDY), or an unrelated word (e.g., CLEAN-FAMILY) projected to either the same or opposite visual field (VF) as the target. In normals, RVF-left hemisphere primes result in high associate priming regardless of target location ( ipsilateral or contralateral to the prime), whereas LVF-right hemisphere primes produce both high and low associate priming across both target location conditions ( Hutchinson, Whitman, Abeare & Raiter, 2003). In contrast, L. S. showed hyperpriming to both high and low associates only in the left hemisphere with inhibition of high associates in the right hemisphere. This case represents a variation of developmental deep dyslexia in which the patient's left hemisphere functions like a normal right hemisphere. However, the lack of exclusively high associate priming in the opposite ( right) hemisphere may not provide the necessary narrowing of semantic activation necessary for normal reading and thus, may lead to semantic reading errors. Theoretical implications are discussed.