title: Cortical thickness abnormalities associated with dyslexia, independent of remediation status.
abstract: Abnormalities in cortical structure are commonly observed in children with dyslexia in key regions of the "reading network." Whether alteration in cortical features reflects pathology inherent to dyslexia or environmental influence (e.g., impoverished reading experience) remains unclear. To address this question, we compared MRI-derived metrics of cortical thickness (CT), surface area (SA), gray matter volume (GMV), and their lateralization across three different groups of children with a historical diagnosis of dyslexia, who varied in current reading level. We compared three dyslexia subgroups with: (1) persistent reading and spelling impairment; (2) remediated reading impairment (normal reading scores), and (3) remediated reading and spelling impairments (normal reading and spelling scores); and a control group of (4) typically developing children. All groups were matched for age, gender, handedness, and IQ. We hypothesized that the dyslexia group would show cortical abnormalities in regions of the reading network relative to controls, irrespective of remediation status. Such a finding would support that cortical abnormalities are inherent to dyslexia and are not a consequence of abnormal reading experience. Results revealed increased CT of the left fusiform gyrus in the dyslexia group relative to controls. Similarly, the dyslexia group showed CT increase of the right superior temporal gyrus, extending into the planum temporale, which resulted in a rightward CT asymmetry on lateralization indices. There were no group differences in SA, GMV, or their lateralization. These findings held true regardless of remediation status. Each reading level group showed the same "double hit" of atypically increased left fusiform CT and rightward superior temporal CT asymmetry. Thus, findings provide evidence that a developmental history of dyslexia is associated with CT abnormalities, independent of remediation status.
authors.affiliation: Department of Neurology, Comprehensive Epilepsy Center, School of Medicine, New York University, New York, NY, USA ; Department of Psychology, New York University, New York, NY, USA.
authors.forename: Yizhou
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Child Mind Institute, New York, NY, USA ; Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA.
authors.forename: Maki S
authors.initials: MS
authors.lastname: Koyama
authors.affiliation: Child Mind Institute, New York, NY, USA ; Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Milham
authors.affiliation: Nathan Kline Institute for Psychiatric Research, Orangeburg, NY, USA ; Child Study Center at NYU Langone Medical Center, New York, NY, USA ; Department of Radiology, School of Medicine, New York University, New York, NY, USA.
authors.forename: F Xavier
authors.initials: FX
authors.lastname: Castellanos
authors.affiliation: Department of Neurology, Comprehensive Epilepsy Center, School of Medicine, New York University, New York, NY, USA.
authors.forename: Brian T
authors.initials: BT
authors.lastname: Quinn
authors.affiliation: Department of Neurology, Comprehensive Epilepsy Center, School of Medicine, New York University, New York, NY, USA.
authors.forename: Heath
authors.initials: H
authors.lastname: Pardoe
authors.affiliation: Department of Neurology, Comprehensive Epilepsy Center, School of Medicine, New York University, New York, NY, USA.
authors.forename: Xiuyuan
authors.initials: X
authors.lastname: Wang
authors.affiliation: Department of Neurology, Comprehensive Epilepsy Center, School of Medicine, New York University, New York, NY, USA.
authors.forename: Ruben
authors.initials: R
authors.lastname: Kuzniecky
authors.affiliation: Department of Neurology, Comprehensive Epilepsy Center, School of Medicine, New York University, New York, NY, USA.
authors.forename: Orrin
authors.initials: O
authors.lastname: Devinsky
authors.affiliation: Department of Neurology, Comprehensive Epilepsy Center, School of Medicine, New York University, New York, NY, USA ; Department of Radiology, School of Medicine, New York University, New York, NY, USA.
authors.forename: Thomas
authors.initials: T
authors.lastname: Thesen
authors.affiliation: Department of Neurology, Comprehensive Epilepsy Center, School of Medicine, New York University, New York, NY, USA.
authors.forename: Karen
authors.initials: K
authors.lastname: Blackmon
mesh_terms: D000293:Adolescent; D001931:Brain Mapping / Q000379:methods; D002540:Cerebral Cortex / Q000473:pathology*; D002648:Child; D004410:Dyslexia / Q000473:pathology*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging; D008297:Male
keywords: Cortical thickness; Dyslexia; Gray matter volume; Lateralization; MRI; Surface area