Journal Article

Cortical maturation and myelination in healthy toddlers and young children

Dean, Douglas C., Dirks, Holly, Deoni, Sean C.L., O’Muircheartaigh, Jonathan, Remer, Justin

2015

Overview

The maturation of cortical structures, and the establishment of their connectivity, are critical neurodevelopmental processes that support and enable cognitive and behavioral functioning. Measures of cortical development, including thickness, curvature, and gyrification have been extensively studied in older children, adolescents, and adults, revealing regional associations with cognitive performance, and alterations with disease or pathology. In addition to these gross morphometric measures, increased attention has recently focused on quantifying more specific indices of cortical structure, in particular intracortical myelination, and their relationship to cognitive skills, including IQ, executive functioning, and language performance. Here we analyze the progression of cortical myelination across early childhood, from 1 to 6years of age, in vivo for the first time. Using two quantitative imaging techniques, namely T1 relaxation time and myelin water fraction (MWF) imaging, we characterize myelination throughout the cortex, examine developmental trends, and investigate hemispheric and gender-based differences. We present a pattern of cortical myelination that broadly mirrors established histological timelines, with somatosensory, motor and visual cortices myelinating by 1year of age; and frontal and temporal cortices exhibiting more protracted myelination. Developmental trajectories, defined by logarithmic functions (increasing for MWF, decreasing for T1), were characterized for each of 68 cortical regions. Comparisons of trajectories between hemispheres and gender revealed no significant differences. Results illustrate the ability to quantitatively map cortical myelination throughout early neurodevelopment, and may provide an important new tool for investigating typical and atypical development. •The maturation of the cerebral cortex is a fundamental process of neurodevelopment.•We examine the myelination of cortical gray matter in a large cohort of children.•We observe a logarithmically increasing trend between MWF and age across the cortex.•Results qualitatively agree with the histological pattern of cortical myelination.•We find a significant correlation between T1 and MWF throughout the cortex.

• Publisher: Elsevier Inc,Elsevier Limited,Academic Press
• Subject: Age / Body Water - metabolism / Brain Mapping / Brain MRI / Cerebral Cortex - growth & development / Child / Child, Preschool / Children & youth / Cognition - physiology / Cognitive ability / Cortical development / Female / Functional Laterality - physiology / Humans / Image Processing, Computer-Assisted / Infant / Infant brain development / Magnetic fields / Magnetic Resonance Imaging / Male / Morphology / Motor Cortex - anatomy & histology / Motor Cortex - growth & development / Myelin Sheath - physiology / Myelination / NMR / Nuclear magnetic resonance / Sex Characteristics / Somatosensory Cortex - anatomy & histology / Somatosensory Cortex - growth & development / Studies / Visual Cortex - anatomy & histology / Visual Cortex - growth & development