Myelin is a fatty sheath composed primarily of oligodendrocyte glycoprotein that insulates the axon and enhances speed and fidelity of neural signal transmission (Tomassy et al. 2016). While myelinated fibers are the main component of brain white matter, significant amounts of myelin are distributed in the gray matter with myelination patterns defining the cortical myeloarchitecture determined from postmortem study (Nieuwenhuys 2013). Over the last decade, a growing number of in vivo MRI studies report converging findings with postmortem patterns of myelination that continues throughout adolescence and into young adulthood (Miller et al. 2012; Nieuwenhuys 2013). Untapped to date is the analysis of multi-site, multimodal, in vivo human neuroimaging data to approximate regional cortical myelin content throughout the adolescent years and into young adulthood. Accordingly, the current analysis addressed this lacuna by estimating cortical myelin of healthy, non-substance misusing adolescents using MRIs from the National Consortium on Alcohol and NeuroDevelopment in Adolescence (NCANDA) study (Brown et al. 2015; Pfefferbaum et al. 2016; Sullivan et al. 2016) and of healthy young adults using comparable data from Human Connectome Project (HCP) (Van Essen et al. 2013).
