Differences in effective connectivity between children with dyslexia, monocular vision and typically developing readers: A DTI study

• We quantified the microstructural attributes of the fascicles of both hemispheres.
• We examine the reading network regions of interest.
• We report differences in Fractional Anisotropy between dyslexic and nondyslexic.
• Differences are in the left Arcuate fasciculus and the genu of the Corpus Callosum.
• It exists different brain connectivity in reading network.

Non-invasive quantitative MRI methods, such as Diffusion Tensor Imaging (DTI) can offer insights into diverse developmental brain disorders such as dyslexia, the most prevalent reading disorder in childhood. In this article, we quantified the microstructural attributes of the main fascicles of both hemispheres related to the reading network in three groups of Spanish children: typically developing readers (TDR or controls), dyslexic readers (DXR) and readers with monocular vision due to ocular motility disorders (MVR), to assess whether the dyslexic children neuronal network for reading shares similarities with the neuronal network for reading in children with impaired binocular vision due to ocular motility disorders or not. Diffusion anisotropy, and mean, radial and axial diffusivity of cross-sectional subregions of the main fascicles studied were computed using a validated DTI methodology. Our results reveal differences in fractional anisotropy (FA) values between the DXR and the non-dyslexic readers, with a decreased FA for the DXR and no significant differences between TDR and MVR groups in the left Arcuate fasciculus, and a tendency to higher FA values in the DXR group compared to the other two groups in the genu of the Corpus Callosum (CC). In the splenium of the CC a trend towards higher FA values was observed in the DXR and MVR groups versus the TDR. This study reveals a different brain connectivity pattern for reading in Spanish children with dyslexia from those with impaired binocular vision due to ocular motility disorders, which would support the hypothesis that ocular motility disorders are not a causal factor of dyslexia.