title: Through Thick and Thin: a Need to Reconcile Contradictory Results on Trajectories in Human Cortical Development.
abstract: Understanding how brain development normally proceeds is a premise of understanding neurodevelopmental disorders. This has sparked a wealth of magnetic resonance imaging (MRI) studies. Unfortunately, they are in marked disagreement on how the cerebral cortex matures. While cortical thickness increases for the first 8-9 years of life have repeatedly been reported, others find continuous cortical thinning from early childhood, at least from age 3 or 4 years. We review these inconsistencies, and discuss possible reasons, including the use of different scanners, recording parameters and analysis tools, and possible effects of variables such as head motion. When tested on the same subsample, 2 popular thickness estimation methods (CIVET and FreeSurfer) both yielded a continuous thickness decrease from 3 years. Importantly, MRI-derived measures of cortical development are merely our best current approximations, hence the term "apparent cortical thickness" may be preferable. We recommend strategies for reaching consensus in the field, including multimodal neuroimaging to measure phenomena using different techniques, for example, the use of T1/T2 ratio, and data sharing to allow replication across analysis methods. As neurodevelopmental origins of early- and late-onset disease are increasingly recognized, resolving inconsistencies in brain maturation trajectories is important.
authors.affiliation: Research Group for Lifespan Changes in Brain and Cognition, Department of Psychology, University of Oslo, Oslo, Norway.
authors.forename: Kristine B
authors.initials: KB
authors.lastname: Walhovd
authors.affiliation: Research Group for Lifespan Changes in Brain and Cognition, Department of Psychology, University of Oslo, Oslo, Norway.
authors.forename: Anders M
authors.initials: AM
authors.lastname: Fjell
authors.affiliation: Department of Psychiatry.
authors.forename: Jay
authors.initials: J
authors.lastname: Giedd
authors.affiliation: Department of Radiology.|Department of Neurosciences.
authors.forename: Anders M
authors.initials: AM
authors.lastname: Dale
authors.affiliation: Department of Neurosciences.|Department of Pediatrics, University of California, San Diego, School of Medicine, La Jolla, CA, USA.
authors.forename: Timothy T
authors.initials: TT
authors.lastname: Brown
mesh_terms: D000818:Animals; D002540:Cerebral Cortex / Q000473:pathology*; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging / Q000379:methods; D009415:Nerve Net / Q000473:pathology*; D055495:Neurogenesis / Q000502:physiology*; D059906:Neuroimaging / Q000379:methods
keywords: MRI; childhood; cortical thickness; maturation; neurodevelopment