Relation of white-matter microstructure to reading ability and disability in beginning readers.

[Correction Notice: An Erratum for this article was reported in Vol 31(5) of Neuropsychology (see record 2017-22816-001). Errors in the dataset owing to two incorrect scores have skewed results. In the 2nd paragraph of the Results section, the 2nd sentence should read: "Within the typical reader group, FA in the left AF correlated negatively with pseudoword reading (WRMT-III Word Attack: rs = .37, p = .064), but not real-word reading (WRMT-III Word Identification: rs = .07, p = .75)." The 4th sentence of the 3rd paragraph should read: "The negative correlation between FA and Word Attack in the typical reader group was driven by Daxial (Dradial: rs = .19, p = .373, Daxial: rs = .38, p = .060)." The 2nd sentence of the 4th paragraph should read: "Results of this analysis replicated those of the larger reading disability group, with a statistically greater reduction of FA in this more severely affected group (p = .008) that was associated with a significant increase in Dradial (p = .008) and no difference in Daxial (p = .47)." In Table 1, for the typical reader group, the resulting values should read: age, 94.00 ± 7.66; KBIT-2-Matrices, 118.31 ± 15.24; WRMT-III-Word Identification, 119.00 ± 9.33; WRMT-III-Word Attack, 114.04 ± 9.31; and TOWRE-2-Sight Word Efficiency, 114.48 ± 8.07. For the reading disability group, the resulting values for age and TOWRE-2- Phonemic Decoding Efficiency should be 93.65 ± 7.81 and 81.76 ± 9.33, respectively. The p values for age and KBIT-2-Matrices should be .87 and .172, respectively. In Figure 3, the image for the typical reader group has been replaced. All versions of this article have been corrected.] Objective: We examined the white-matter microstructure of the left arcuate fasciculus, which has been associated with reading ability, in beginning readers with or without reading disability.
Method: Groups were typically reading children (n = 26) or children with reading disability (n = 26), Ages 6-9, and equated on nonverbal cognitive abilities. Diffusion-weighted images were collected and TRACULA was used to extract fractional anisotropy measures from the left arcuate fasciculus.
Results: White-matter microstructure was altered in children with reading disability, who exhibited significantly reduced fractional anisotropy in the left arcuate fasciculus. Among typically reading children, lower fractional anisotropy of the left arcuate fasciculus was associated with superior pseudoword reading performance. Both the group differences and variation in reading scores among the children with reading disability were associated with radial diffusivity (but not axial diffusivity), whereas variation in reading scores among typically reading children was associated with axial diffusivity (but not radial diffusivity).
Conclusions: The paradoxical findings that lower fractional anisotropy was associated both with reading disability and also with better phonological awareness in typical reading development suggest that there are different maturational trajectories of white-matter microstructure in typical readers and children with reading disability, and that this difference is unique to the beginning stages of reading acquisition. The finding that reading disability was associated with radial diffusivity, but that variation in ability among typically developing readers was associated with axial diffusivity, suggests that different neural mechanisms may be associated with reading development in children with or without reading disability. (PsycINFO Database Record
((c) 2017 APA, all rights reserved).)