Posterior-vertical White Matter Tracts Cluster with Ventral Stream Tracts in Development and Predict Behavioral Variability
A relatively unexplored group of white matter tracts has been recently described and made available for scientific investigation. These posterior vertical white matter tracts connect cortical regions associated with the ventral and dorsal visual streams, making them distinct from the well-studied, canonical tracts that connect anterior and posterior cortical regions. We utilized diffusion MRI and open-source cloud computing to characterize the development of vertical white matter tracts in a cross-sectional sample of 24 children (5-8 years old) and 12 adults (18-22 years old). Horizontal tracts within the ventral visual stream (ILF, IFOF) had FA that was more adult-like than horizontal tracts in the dorsal cortex (SLF1/2 and SLF3), consistent with prior work. Results from a clustering analysis demonstrated that the mean FA of the posterior vertical tracts (pArc, TPC, MdLF-spl, MDLF-ang) was more similar to that of the ventral tracts than the dorsal tracts. Performance on a perceptual matching task predicted FA in the pArc in the child sample. Our results suggest that posterior vertical tracts develop later than ventral stream tracts but earlier than tracts in the dorsal cortex and that the development of posterior vertical tracts may be related to the influence of perceptual processing on dorsally mediated action in childhood.