Chapter

A Neurological Account of Dyslexia

Jean-François Démonet and Caroline Reilhac

in Visual Aspects of Dyslexia

Published in print August 2012 | ISBN: 9780199589814
Published online September 2012 | e-ISBN: 9780191744785 | DOI: http://dx.doi.org/10.1093/acprof:oso/9780199589814.003.0001
A Neurological Account of Dyslexia

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Imaging studies in dyslexic subjects have revealed structural abnormalities of the brain, defective activity and abnormal connectivity between regions crucial for language functions. These findings provide a neurobiological signature for dyslexia, specifically disruption of two left-hemispheric posterior systems, a parieto-temporal network and an occipito-temporal network; these dysfunctions can be compensated for by the engagement of anterior and right posterior (occipito-temporal) territories. The combination of different brain imaging modalities (Morphometric MRI, Positron Emission Tomography, functional MRI, etc.) with cognitive studies has contributed to better understanding of the written language deficits in dyslexic subjects. Overall, findings highlight the heterogeneity of the dyslexia phenotype and demonstrate that far from being mutually exclusive, the main theories that have been advanced as to its aetiology probably each relate to different aspects of its causation. This chapter covers some of the main results of brain imaging studies that describe the structural and functional abnormalities in adults and children with dyslexia.

Keywords: structural; imaging studies; neurological; MRI; cognitive

Chapter.  7536 words. 

Subjects: Neuroscience

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