Age dependency and lateralization in the three branches of the human superior longitudinal fasciculus

The superior longitudinal fascicle/fasciculus (SLF) is a major white matter tract connecting the frontal and parietal cortices in humans. Although SLF has often been analyzed as single entity, several studies have reported that segregated into three distinct branches (SLF I, II, III). They also right lateralization of III volume discussed its relationship with lateralized cortical functions fronto-parietal network. However, to date, homogeneity or heterogeneity age dependency properties not fully clarified. Through this study, we aimed clarify I-III by analyzing diffusion-weighted MRI (dMRI) quantitative R1 (qR1) map datasets collected from wide range groups, mostly comprising right-handed children, adolescents, adults, seniors (6 81 years old). dMRI measurement (fractional anisotropy, FA) was heterogeneous among branches, suggesting these are regulated developmental aging processes. Lateralization analysis on revealed larger than left replicating previous reports. FA suggested that, addition III, II hemisphere adolescents adults. We further found I qR1 data, microstructural sensitive myelin levels, These findings suggest sub-bundles entities terms lateralization.