title: Distinct neural signatures of cognitive subtypes of dyslexia with and without phonological deficits.
abstract: Developmental dyslexia can be distinguished as different cognitive subtypes with and without phonological deficits. However, despite some general agreement on the neurobiological basis of dyslexia, the neurofunctional mechanisms underlying these cognitive subtypes remain to be identified. The present BOLD fMRI study thus aimed at investigating by which distinct and/or shared neural activation patterns dyslexia subtypes are characterized. German dyslexic fourth graders with and without deficits in phonological awareness and age-matched normal readers performed a phonological decision task: does the auditory word contain the phoneme/a/? Both dyslexic subtypes showed increased activation in the right cerebellum (Lobule IV) compared to controls. Subtype-specific increased activation was systematically found for the phonological dyslexics as compared to those without this deficit and controls in the left inferior frontal gyrus (area 44: phonological segmentation), the left SMA (area 6), the left precentral gyrus (area 6) and the right insula. Non-phonological dyslexics revealed subtype-specific increased activation in the left supramarginal gyrus (area PFcm; phonological storage) and angular gyrus (area PGp). The study thus provides the first direct evidence for the neurobiological grounding of dyslexia subtypes. Moreover, the data contribute to a better understanding of the frequently encountered heterogeneous neuroimaging results in the field of dyslexia.
authors.affiliation: Section Structural-Functional Brain Mapping, Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University, Germany ; JARA-Translational Brain Medicine, Germany.
authors.forename: Muna
authors.initials: M
authors.lastname: van Ermingen-Marbach
authors.affiliation: Section Neurological Cognition Research, Department of Neurology, Medical School, RWTH Aachen University, Germany.
authors.forename: Marion
authors.initials: M
authors.lastname: Grande
authors.affiliation: Section Neurological Cognition Research, Department of Neurology, Medical School, RWTH Aachen University, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Pape-Neumann
authors.affiliation: Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University, Germany ; JARA-Translational Brain Medicine, Germany.
authors.forename: Katharina
authors.initials: K
authors.lastname: Sass
authors.affiliation: Section Structural-Functional Brain Mapping, Department of Psychiatry, Psychotherapy and Psychosomatics, Medical School, RWTH Aachen University, Germany ; Section Neurological Cognition Research, Department of Neurology, Medical School, RWTH Aachen University, Germany ; Research Centre Jülich, Institute of Neuroscience and Medicine (INM-1), Germany ; JARA-Translational Brain Medicine, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Heim
keywords: Children; Cognitive subtypes; Dyslexia; Neuroimaging; Phonological deficit; Reading