Quantitative tract-based white matter development from birth to age 2 years

Abstract

Few large-scale studies have been done to characterize the normal human brain white matter growth in the first years of life. We investigated white matter maturation patterns in major fiber pathways in a large cohort of healthy young children from birth to age two using diffusion parameters fractional anisotropy (FA), radial diffusivity (RD) and axial diffusivity (RD). Ten fiber pathways, including commissural, association and projection tracts, were examined with tract-based analysis, providing more detailed and continuous spatial developmental patterns compared to conventional ROI based methods. All DTI data sets were transformed to a population specific atlas with a group-wise longitudinal large deformation diffeomorphic registration approach. Diffusion measurements were analyzed along the major fiber tracts obtained in the atlas space. All fiber bundles show increasing FA values and decreasing radial and axial diffusivities during the development in the first two years of life. The changing rates of the diffusion indices are faster in the first year than the second year for all tracts. RD and FA show larger percentage changes in the first and second years than AD. The gender effects on the diffusion measures are small. Along different spatial locations of fiber tracts, maturation does not always follow the same speed. Temporal and spatial diffusion changes near cortical regions are in general smaller than changes in central regions. Overall developmental patterns revealed in our study confirm the general rules of white matter maturation. This work shows a promising framework to study and analyze white matter maturation in a tract-based fashion. Compared to most previous studies that are ROI-based, our approach has the potential to discover localized development patterns associated with fiber tracts of interest.

Postnatal growth of the human optic nerve

“…These changes are consistent with previously reported developmental increases in ON myelin density. 4 The mean newborn ON is 25.3+/ − mm in length, reaching 45.3 (adult) by 20 years of age. Human ON growth is linear in the first 3 years of life, reaching 86% of the total adult length by this time (Figure 2; area indicated by (1): slope y = 4.55x+24.214; r 2 = 0.9991).…”

Long‐term white matter tract reorganization following prolonged febrile seizures

“…Therefore, myelination occurs in brainstem WM before cerebral WM, in central WM before peripheral WM, and in projection and commissural pathways before association pathways. The rate of maturation of WM tracts, however, is not linear, with a steep increase in the first year after birth and a slower rate in the following years 19, 20, 23, 24, 25. In addition, WM tracts less mature at birth (e.g.…”

“…peripheral WM) have a faster rate of maturation in early childhood compared to those more mature at birth (e.g. corticospinal tracts), and therefore may be more vulnerable to insults during this period 19, 23, 24, 26, 27…”

The emergence of functional architecture during early brain development

“…White matter maturation, including axonal growth, increasing axonal coherence and myelination can be clearly delineated using DWI (Braga et al, 2015;Geng et al, 2012;Hagmann et al, 2010;Huppi et al, 1998;Sadeghi et al, 2013).…”