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Surface errors without semantic impairment in acquired dyslexia: a voxel-based lesion-symptom mapping study. Brain 2016 05;139(Pt 5):1517-26

Date

03/12/2016

Pubmed ID

26966139

Pubmed Central ID

PMC5006249

DOI

10.1093/brain/aww029

Scopus ID

2-s2.0-84966648862   22 Citations

Abstract

Patients with surface dyslexia have disproportionate difficulty pronouncing irregularly spelled words (e.g. pint), suggesting impaired use of lexical-semantic information to mediate phonological retrieval. Patients with this deficit also make characteristic 'regularization' errors, in which an irregularly spelled word is mispronounced by incorrect application of regular spelling-sound correspondences (e.g. reading plaid as 'played'), indicating over-reliance on sublexical grapheme-phoneme correspondences. We examined the neuroanatomical correlates of this specific error type in 45 patients with left hemisphere chronic stroke. Voxel-based lesion-symptom mapping showed a strong positive relationship between the rate of regularization errors and damage to the posterior half of the left middle temporal gyrus. Semantic deficits on tests of single-word comprehension were generally mild, and these deficits were not correlated with the rate of regularization errors. Furthermore, the deep occipital-temporal white matter locus associated with these mild semantic deficits was distinct from the lesion site associated with regularization errors. Thus, in contrast to patients with surface dyslexia and semantic impairment from anterior temporal lobe degeneration, surface errors in our patients were not related to a semantic deficit. We propose that these patients have an inability to link intact semantic representations with phonological representations. The data provide novel evidence for a post-semantic mechanism mediating the production of surface errors, and suggest that the posterior middle temporal gyrus may compute an intermediate representation linking semantics with phonology.

Author List

Binder JR, Pillay SB, Humphries CJ, Gross WL, Graves WW, Book DS

Authors

Jeffrey R. Binder MD Professor in the Neurology department at Medical College of Wisconsin
Diane S. Book MD Associate Professor in the Neurology department at Medical College of Wisconsin
William Gross MD, PhD Assistant Professor in the Anesthesiology department at Medical College of Wisconsin
Sara B. Pillay PhD Assistant Professor in the Neurology department at Medical College of Wisconsin




MESH terms used to index this publication - Major topics in bold

Adult
Aged
Aged, 80 and over
Brain Mapping
Dyslexia, Acquired
Female
Humans
Male
Middle Aged
Neuropsychological Tests
Occipital Lobe
Phonetics
Semantics
Stroke
Temporal Lobe
White Matter