title: Functional neuroanatomical evidence for the double-deficit hypothesis of developmental dyslexia.
abstract: The double-deficit hypothesis of dyslexia posits that both rapid naming and phonological impairments can cause reading difficulties, and that individuals who have both of these deficits show greater reading impairments compared to those with a single deficit. Despite extensive behavioral research, the brain basis of poor reading with a double-deficit has never been investigated. The goal of the study was to evaluate the double-deficit hypothesis using functional MRI. Activation patterns during a printed word rhyme judgment task in 90 children with a wide range of reading abilities showed dissociation between brain regions that were sensitive to phonological awareness (left inferior frontal and inferior parietal regions) and rapid naming (right cerebellar lobule VI). More specifically, the double-deficit group showed less activation in the fronto-parietal reading network compared to children with only a deficit in phonological awareness, who in turn showed less activation than the typically-reading group. On the other hand, the double-deficit group showed less cerebellar activation compared to children with only a rapid naming deficit, who in turn showed less activation than the typically-reading children. Functional connectivity analyses revealed that bilateral prefrontal regions were key for linking brain regions associated with phonological awareness and rapid naming, with the double-deficit group being the most aberrant in their connectivity. Our study provides the first functional neuroanatomical evidence for the double-deficit hypothesis of developmental dyslexia.
authors: Department of Brain and Cognitive Sciences and McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors: Elizabeth S
authors: ES
authors: Norton
authors: Graduate School of Social Work, Boston College, Chestnut Hill, MA 02467, USA.
authors: Jessica M
authors: JM
authors: Black
authors: Child and Adolescent Psychiatry, Department of Psychiatry, University of California, San Francisco, CA 94143, USA; Pacific Graduate School of Psychology, Palo Alto University, Palo Alto, CA 94304, USA.
authors: Leanne M
authors: LM
authors: Stanley
authors: Child and Adolescent Psychiatry, Department of Psychiatry, University of California, San Francisco, CA 94143, USA; Department of Neuropsychology, Children's Healthcare of Atlanta, and Emory University School of Medicine, Atlanta, GA 30322, USA.
authors: Hiroko
authors: H
authors: Tanaka
authors: Department of Brain and Cognitive Sciences and McGovern Institute for Brain Research, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Institute for Medical Engineering & Science, Cambridge, MA 02139, USA.
authors: John D E
authors: JD
authors: Gabrieli
authors: Child and Adolescent Psychiatry, Department of Psychiatry, University of California, San Francisco, CA 94143, USA; Department of Pediatrics, Duke University School of Medicine, Durham, NC 27710, USA.
authors: Carolyn
authors: C
authors: Sawyer
authors: Child and Adolescent Psychiatry, Department of Psychiatry, University of California, San Francisco, CA 94143, USA; Haskins Laboratories, New Haven, CT 06511, USA; Department of Neuropsychiatry, Keio University School of Medicine, Tokyo 160, Japan. Electronic address: fumiko.hoeft@ucsf.edu.
authors: Fumiko
authors: F
authors: Hoeft
mesh_terms: D001921:Brain / Q000503:physiopathology*; D002648:Child; D004410:Dyslexia / Q000503:physiopathology*; D005260:Female; D006801:Humans; D007600:Judgment / Q000502:physiology; D007807:Language Tests; D008279:Magnetic Resonance Imaging; D008297:Male; D008960:Models, Psychological; D009434:Neural Pathways / Q000503:physiopathology; D009483:Neuropsychological Tests; D010700:Phonetics; D011932:Reading; D012815:Signal Processing, Computer-Assisted
keywords: Developmental dyslexia; Double deficit; Phonological processing; Reading; fMRI