title: When transparency is opaque: Effects of diacritic marks and vowel letters on dyslexic Hebrew readers.
abstract: The current study examined the effects of orthographic transparency and familiarity on brain mechanisms involved in word recognition in adult dyslexic Hebrew readers. We compared functional Magnetic Resonance Imaging (fMRI) brain activation in 21 dyslexic readers and 22 typical readers, and examined the effects of diacritic marks that provide transparent but less familiar information and vowel letters that increase orthographic transparency without compromising familiarity. Dyslexic readers demonstrated reduced activation in left supramarginal gyrus (SMG) as compared to typical readers, as well as different patterns of activation within the left inferior frontal gyrus (IFG). Furthermore, in contrast to typical readers, dyslexic readers did not show increased activation for diacritics in left temporo-parietal junction regions, associated with mapping orthography to phonology. Nevertheless, both groups showed the facilitation effect of vowel letters on regions associated with lexical-semantic access. Altogether the results suggest that while typical readers can compensate for the reduced familiarity of pointed words with increased reliance on decoding of smaller units, dyslexic readers do not, and therefore they show a higher cost.
authors.affiliation: Department of Communication Sciences and Disorders, University of Texas at Austin, Austin, TX, USA. Electronic address: yael.weiss@austin.utexas.edu.
authors.forename: Yael
authors.initials: Y
authors.lastname: Weiss
authors.affiliation: Department of Learning Disabilities, The E.J. Safra Brain Research Center for the Study of Learning Disabilities, University of Haifa, Israel. Electronic address: katzirta@gmail.com.
authors.forename: Tami
authors.initials: T
authors.lastname: Katzir
authors.affiliation: Psychology Department and Institute for Information Processing and Decision Making, University of Haifa, Israel. Electronic address: tbitan@research.haifa.ac.il.
authors.forename: Tali
authors.initials: T
authors.lastname: Bitan
mesh_terms: D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging* / Q000503:physiopathology; D004410:Dyslexia / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006801:Humans; D007802:Language; D008279:Magnetic Resonance Imaging; D008297:Male; D010364:Pattern Recognition, Visual / Q000502:physiology*; D010775:Photic Stimulation; D011930:Reaction Time / Q000502:physiology; D011932:Reading; D021641:Recognition, Psychology / Q000502:physiology*; D055815:Young Adult
keywords: Dyslexia; Familiarity; Orthographic transparency; Phonology; fMRI