Heterogeneity of Human White Matter Development: Diffusivity Parameters Decrease Fastest in the Center of White Matter Tracts, from 5 to 19 Years of Age

Shu-Wei Sun¹, ², Nirmalya Ghosh¹, Karen Tong¹, Barbara Holshouser¹, Stephen Ashwal¹

We compared changes in whole brain DTI parameters taken from the center of white matter tracts to parameters from the entire tract to evaluate the homogeneity of white matter maturation in children and adolescents between 5-19 years old. The white matter area increased ~2.5 times but the length of tracts only increased ~1.5 times. White matter maturation is not homogeneous within the tracts. Diffusivity decreases faster in the center compared to the edges of the white matter tracts suggesting greater myelin development and compactness which may provide greater resistance to shearing injuries compared to the gray-white matter junction.