title: Cognitive levels of performance account for hemispheric lateralisation effects in dyslexic and normally reading children.
abstract: Recent theories of developmental dyslexia explain reading deficits in terms of deficient phonological awareness, attention, visual and auditory processing, or automaticity. Since dyslexia has a neurobiological basis, the question arises how the reader's proficiency in these cognitive variables affects the brain regions involved in visual word recognition. This question was addressed in two fMRI experiments with 19 normally reading children (Experiment 1) and 19 children with dyslexia (Experiment 2). First, reading-specific brain activation was assessed by contrasting the BOLD signal for reading aloud words vs. overtly naming pictures of real objects. Next, ANCOVAs with brain activation during reading the individuals' scores for all five cognitive variables assessed outside the scanner as covariates were performed. Whereas the normal readers' brain activation during reading showed co-variation effects predominantly in the right hemisphere, the reverse pattern was observed for the dyslexics. In particular, middle frontal gyrus, inferior parietal cortex, and precuneus showed contralateral effects for controls as compared to dyslexics. In line with earlier findings in the literature, these data hint at a global change in hemispheric asymmetry during cognitive processing in dyslexic readers, which, in turn, might affect reading proficiency.
authors.affiliation: Department of Psychiatry and Psychotherapy, University Hospital Aachen, RWTH Aachen University, Aachen, Germany. sheim@ukaachen.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Heim
authors.forename: Marion
authors.initials: M
authors.lastname: Grande
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Meffert
authors.forename: Simon B
authors.initials: SB
authors.lastname: Eickhoff
authors.forename: Helen
authors.initials: H
authors.lastname: Schreiber
authors.forename: Juraj
authors.initials: J
authors.lastname: Kukolja
authors.forename: Nadim Jon
authors.initials: NJ
authors.lastname: Shah
authors.forename: Walter
authors.initials: W
authors.lastname: Huber
authors.forename: Katrin
authors.initials: K
authors.lastname: Amunts
mesh_terms: D001921:Brain / Q000502:physiology*; D001931:Brain Mapping; D002648:Child; D003071:Cognition / Q000502:physiology*; D004410:Dyslexia / Q000503:physiopathology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D011932:Reading