Altered white matter connectivity in 8-10 year old dyslexic children

Zaric, G. 1 , Timmers, I. 1 , Gerretsen, P. 2 , Fraga González, G. 3 , Tijms, J. 4 , van der Molen, M. W. 3 , Blomert, L. 1 & Bonte, M. 1

1 Maastricht University
2 Regionaal Instituut voor Dyslexie
3 University of Amsterdam
4 IWAL institute

Reading is a complex cognitive skill subserved by a distributed network of brain regions involved in visual, spoken language and cognitive functions. Atypical structural properties of white matter bundles connecting these regions have been associated with impaired reading acquisition in developmental dyslexia. Here, we investigated functional anisotropy (FA) values of white matter bundles in Dutch 9-year-old dyslexic (n=21) and typically reading (n=15) children. To this end we employed the AFQ toolbox. Our results show a tendency towards higher FA values in typical than dyslexic readers along multiple tracts of the reading network, and especially in the right uncinate fasciculus which scaled with reading and phoneme deletion accuracy. In contrast, dyslexic readers showed higher FA values in the right thalamic radiation and across groups these FA values were inversely related to reading fluency scores. Additionally, higher FA values along the bilateral thalamic radiations were related to slower rapid automatized naming. Although speculative at this point, enhanced FA values in the right thalamic radiation might relate to increased and/or more effortful engagement of multisensory processes in dyslexic readers.