Abstract
The human brain development is a complicated yet well-organized process. Metrics derived from diffusion tensor imaging (DTI), including fractional anisotropy (FA), radial (RD), axial (AxD), and mean diffusivity (MD), have been used to noninvasively access the microstructural development of human brain white matter (WM). At birth, most of the major WM tracts are apparent but in a relatively disorganized pattern. Brain maturation is a process of establishing an organized pattern of these major WM tracts. However, how the linkage pattern of major WM tracts changes during development remains unclear. In this study, DTI data of 26 neonates and 28 children around puberty were acquired. 10 major WM tracts, representing four major tract groups involved in distinctive brain functions, were traced with DTI tractography for all 54 subjects. With the 10 by 10 correlation matrices constructed with Spearman's pairwise inter-tract correlations and based on tract-level measurements of FA, RD, AxD, and MD of both age groups, we assessed if the inter-tract correlations become stronger from birth to puberty. In addition, hierarchical clustering was performed based on the pairwise correlations of WM tracts to reveal the clustering pattern for each age group and pattern shift from birth to puberty. Stronger and enhanced microstructural inter-tract correlations were found during development from birth to puberty. The linkage patterns of two age groups differ due to brain development. These changes of microstructural correlations from birth to puberty suggest inhomogeneous but organized myelination processes which cause the reshuffled inter-tract correlation pattern and make homologous tracts tightly clustered. It opens a new window to study WM tract development and can be potentially used to investigate atypical brain development due to neurological or psychiatric disorders.
Highlights
The human brain is complicated yet well organized
CHANGES OF WHITE MATTER MICROSTRUCTURE FROM NEONATES TO CHILDREN AROUND PUBERTY Figure 1 shows the three-dimensional (3D) visualization of the traced 10 major white matter (WM) tracts for a typical neonate and a typical child around puberty. These 10 major tracts, namely CST_L, CST_R, IFO_L, IFO_R, CGC_L, CGC_R, CGH_L, CGH_R, forceps major (FMajor) and forceps minor (FMinor), cover projection, limbic, association and commissural tract groups involved in distinct brain functions
For all 10 major WM tracts, fractional anisotropy (FA) values are higher in the child group than those of the neonate group while mean diffusivity (MD), axial diffusivity (AxD), and RD values of the child group are less
Summary
The major cerebral white matter (WM) tracts connecting different brain regions are involved in different brain functions. These major cerebral WM tracts are often categorized into different tract groups based on their distinct functions. There are roughly four tract groups, namely limbic, projection, callosal, and association tract groups (e.g., Wakana et al, 2004; Huang et al, 2012a,b), for cerebral WM tracts. The WM tracts within a tract group perform similar functions. Most of major WM tracts are well formed (e.g., Huang et al, 2006; Oishi et al, 2011), except the arcuate fasciculus which is a part of the superior longitudinal fasciculus (SLF) and related to language function
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
