A Large-Scale Investigation of White Matter Microstructural Associations with Reading Ability

Abstract

Reading involves the functioning of a widely distributed brain network, and white matter tracts are responsible for sending information between constituent network nodes. Several studies have analyzed fiber bundle microstructural properties to shed insights into the neural basis of reading abilities and disabilities. Findings have been inconsistent, potentially due to small sample sizes and varying methodology. To address this, we analyzed a large data set of 690 children ages 5-18 using state-of-the-art neuroimaging acquisitions and processing techniques. We searched for associations between fractional anisotropy (FA) and single-word and nonword reading skills in both typical and poor readers across multiple tracts previously thought to contribute to reading. Consistent with prior studies, FA increased with age across all tracts. There were significant correlations between better reading skills and higher FA in several fiber bundles among poor readers, but fewer and occasionally negative associations among proficient readers. The left superior longitudinal fasciculus and arcuate fasciculus unexpectedly exhibited higher FA within those diagnosed with reading disabilities compared to those without a diagnosis, while their right-hemisphere homologs exhibited higher FA in those with higher reading scores, regardless of diagnostic status. These results suggest a different relation between white matter pathways in children with typical reading ability versus those with reading disabilities. Highlights Fractional anisotropy (FA) positively correlated with age across all examined tracts. We looked for group differences in FA and correlations between FA and reading skills. Those with reading disabilities had higher FA in left-hemisphere reading tracts. Several tracts’ FA positively correlated with reading skills among poor readers. Few tracts’ FA correlated with reading skill among proficient readers.