Gray Matter Features of Reading Disability: A Combined Meta-Analytic and Direct Analysis Approach(1,2,3,4).

Mark A Eckert,Kenneth I Vaden,Virginia W Berninger,Loretta Tsu,Mulugeta Gebregziabher

doi:10.1523/eneuro.0103-15.2015

Abstract

Meta-analysis of voxel-based morphometry dyslexia studies and direct analysis of 293 reading disability and control cases from six different research sites were performed to characterize defining gray matter features of reading disability. These analyses demonstrated consistently lower gray matter volume in left posterior superior temporal sulcus/middle temporal gyrus regions and left orbitofrontal gyrus/pars orbitalis regions. Gray matter volume within both of these regions significantly predicted individual variation in reading comprehension after correcting for multiple comparisons. These regional gray matter differences were observed across published studies and in the multisite dataset after controlling for potential age and gender effects, and despite increased anatomical variance in the reading disability group, but were not significant after controlling for total gray matter volume. Thus, the orbitofrontal and posterior superior temporal sulcus gray matter findings are relatively reliable effects that appear to be dependent on cases with low total gray matter volume. The results are considered in the context of genetics studies linking orbitofrontal and superior temporal sulcus regions to alleles that confer risk for reading disability.

Highlights

Reading disability affects at least 5–15% of the U.S population (Shaywitz et al, 1990; Katusic et al, 2001; Yoshimasu et al, 2010) for which there are varied patterns of oral and written language problems (Torppa et al, 2007; Archibald et al, 2013; McArthur et al, 2013)
Lower gray matter volume in reading disability compared with control cases was observed in left orbitofrontal cortex/pars orbitalis of the inferior frontal gyrus/(MNI: Ϫ38, 36, Ϫ14; Z ϭ 2.49), left eNeuro.sfn.org posterior superior temporal sulcus/middle temporal gyrus (MNI: Ϫ56, Ϫ56, 8; Z ϭ 2.74), and right cerebellar hemisphere (MNI: 24, Ϫ68, Ϫ42; Z ϭ 2.36) regions across studies
Reading disability and poor cloze reading comprehension occurs with low gray matter volume in left orbitofrontal gyrus/pars orbitalis and left posterior superior temporal sulcus/middle temporal gyrus regions compared with typical readers based on a meta-analysis of the extant voxelbased reading disability literature and direct analysis of multisite data

Summary

Introduction

Reading disability affects at least 5–15% of the U.S population (Shaywitz et al, 1990; Katusic et al, 2001; Yoshimasu et al, 2010) for which there are varied patterns of oral and written language problems (Torppa et al, 2007; Archibald et al, 2013; McArthur et al, 2013). Meta-analyses of findings from voxel-based gray matter studies of reading disability (Linkersdörfer et al, 2012; Richlan et al, 2013) suggest that people with reading disability exhibit lower gray matter volume at the posterior end of the Sylvian fissure, the fusiform gyrus, and cerebellar regions where gross volumetric and/or atypical asymmetry effects have been observed (Leonard et al, 2001; Rae et al, 2002; Fernandez et al, 2013). Each of these brain regions has been linked to reading and/or reading disability in functional imaging studies (Maisog et al, 2008; Paulesu et al, 2014) and are targets for understanding reading disability

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