title: Cortical maturation and myelination in healthy toddlers and young children.
abstract: 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 6 years 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 1 year 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.
authors.affiliation: Department of Pediatric Radiology, Children's Hospital Colorado, Aurora, CO, 80045, USA; Department of Radiology, University of Colorado Denver, Aurora, CO, 80045, USA; Advanced Baby Imaging Lab, Brown University School of Engineering, Providence, RI, 02912, USA. Electronic address: sdeoni@mac.com.
authors.forename: Sean C L
authors.initials: SC
authors.lastname: Deoni
authors.affiliation: Waisman Laboratory for Brain Imaging and Behavior, University of Wisconsin-Madison, Madison, WI, 53705, USA.
authors.forename: Douglas C
authors.initials: DC
authors.lastname: Dean
authors.affiliation: Advanced Baby Imaging Lab, Brown University School of Engineering, Providence, RI, 02912, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Remer
authors.affiliation: Advanced Baby Imaging Lab, Brown University School of Engineering, Providence, RI, 02912, USA.
authors.forename: Holly
authors.initials: H
authors.lastname: Dirks
authors.affiliation: Department of Neuroimaging, King's College London, Institute of Psychiatry, London SE5 8AF, United Kingdom.
authors.forename: Jonathan
authors.initials: J
authors.lastname: O'Muircheartaigh
mesh_terms: D001834:Body Water / Q000378:metabolism; D001931:Brain Mapping; D002540:Cerebral Cortex / Q000254:growth & development*; D002648:Child; D002675:Child, Preschool; D003071:Cognition / Q000502:physiology; D005260:Female; D007839:Functional Laterality / Q000502:physiology; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D009044:Motor Cortex / Q000033:anatomy & histology / Q000254:growth & development; D009186:Myelin Sheath / Q000502:physiology*; D012727:Sex Characteristics; D013003:Somatosensory Cortex / Q000033:anatomy & histology / Q000254:growth & development; D014793:Visual Cortex / Q000033:anatomy & histology / Q000254:growth & development
keywords: Brain MRI; Cortical development; Infant brain development; Myelination