Longitudinal Mapping of Cortical Thickness and Brain Growth in Normal Children

TLDR

Advances in MRI now enable longitudinal mapping of developmental changes in children’s brains. The study used computer‑matching algorithms and novel cortical‑thickness measurement techniques on serial MRI scans of 45 children aged 5–11, taken two years apart. Longitudinal analysis revealed that cortical thickness ranged from 1.5 mm in occipital to 5.5 mm in dorsomedial frontal cortex, with local brain growth of ~0.4–1.5 mm yr⁻¹ mainly in frontal and occipital areas, gray‑matter thinning accompanied cortical expansion in right frontal and bilateral parieto‑occipital regions, while thickening was confined to left inferior frontal and bilateral posterior perisylvian zones, and thickness changes in the left hemisphere correlated with cognitive development—marking the first simultaneous longitudinal mapping of gray‑matter thickness, brain size, and structure‑function relationships in children.

Abstract

Recent advances in magnetic resonance imaging (MRI) technology now allow the tracing of developmental changes in the brains of children. We applied computer-matching algorithms and new techniques for measuring cortical thickness (in millimeters) to the structural MRI images of 45 children scanned twice (2 yr apart) between the ages 5 and 11. Changes in brain size were also assessed, showing local brain growth progressing at a rate of ∼0.4-1.5 mm per year, most prominently in frontal and occipital regions. Estimated cortical thickness ranged from 1.5 mm in occipital regions to 5.5 mm in dorsomedial frontal cortex. Gray matter thinning coupled with cortical expansion was highly significant in right frontal and bilateral parieto-occipital regions. Significant thickening was restricted to left inferior frontal (Broca's area) and bilateral posterior perisylvian (Wernicke's area on the left) regions. In the left hemisphere, gray matter thickness was correlated with changing cognitive abilities. For the first time, developmental changes in gray matter thickness, brain size, and structure-function relationships have been traced within the same individuals studied longitudinally during a time of rapid cognitive development.