title: Synergistic Effects of Age on Patterns of White and Gray Matter Volume across Childhood and Adolescence
abstract: The human brain develops with a nonlinear contraction of gray matter across late childhood and adolescence with a concomitant increase in white matter volume. Across the adult population, properties of cortical gray matter covary within networks that may represent organizational units for development and degeneration. Although gray matter covariance may be strongest within structurally connected networks, the relationship to volume changes in white matter remains poorly characterized. In the present study we examined age-related trends in white and gray matter volume using T1-weighted MR images from 360 human participants from the NIH MRI study of Normal Brain Development. Images were processed through a voxel-based morphometry pipeline. Linear effects of age on white and gray matter volume were modeled within four age bins, spanning 4-18 years, each including 90 participants (45 male). White and gray matter age-slope maps were separately entered into k-means clustering to identify regions with similar age-related variability across the four age bins. Four white matter clusters were identified, each with a dominant direction of underlying fibers: anterior-posterior, left-right, and two clusters with superior-inferior directions. Corresponding, spatially proximal, gray matter clusters encompassed largely cerebellar, fronto-insular, posterior, and sensorimotor regions, respectively. Pairs of gray and white matter clusters followed parallel slope trajectories, with white matter changes generally positive from 8 years onward (indicating volume increases) and gray matter negative (decreases). As developmental disorders likely target networks rather than individual regions, characterizing typical coordination of white and gray matter development can provide a normative benchmark for understanding atypical development.
authors.affiliation: Department of Radiology, Cumming School of Medicine, University of Calgary , Calgary, Alberta, Canada T2N 1N4 ; Department of Pediatrics, Cumming School of Medicine, University of Calgary , Calgary, Alberta, Canada T2N 1N4 ; Child and Adolescent Imaging Research Program, Alberta Children's Hospital , Calgary, Alberta, Canada T3B 6A8 ; Alberta Children's Hospital Research Institute , Calgary, Alberta, Canada T3B 6A8.
authors.forename: Signe
authors.initials: S
authors.lastname: Bray
authors.affiliation: Child and Adolescent Imaging Research Program, Alberta Children's Hospital , Calgary, Alberta, Canada T3B 6A8 ; Alberta Children's Hospital Research Institute , Calgary, Alberta, Canada T3B 6A8 ; Biomedical Engineering Graduate Program, University of Calgary , Calgary, Alberta, Canada T2N 1N4.
authors.forename: Mark
authors.initials: M
authors.lastname: Krongold
authors.affiliation: Child and Adolescent Imaging Research Program, Alberta Children's Hospital , Calgary, Alberta, Canada T3B 6A8 ; Alberta Children's Hospital Research Institute , Calgary, Alberta, Canada T3B 6A8.
authors.forename: Cassandra
authors.initials: C
authors.lastname: Cooper
authors.affiliation: Department of Radiology, Cumming School of Medicine, University of Calgary , Calgary, Alberta, Canada T2N 1N4 ; Department of Pediatrics, Cumming School of Medicine, University of Calgary , Calgary, Alberta, Canada T2N 1N4 ; Child and Adolescent Imaging Research Program, Alberta Children's Hospital , Calgary, Alberta, Canada T3B 6A8 ; Alberta Children's Hospital Research Institute , Calgary, Alberta, Canada T3B 6A8.
authors.forename: Catherine
authors.initials: C
authors.lastname: Lebel
keywords: MRI; cortex; structural covariance network; white matter