School of Psychology and Centre for Social and Early Emotional Development (SEED), Deakin University, Geelong, Australia.
Neuroscience Advanced Clinical Imaging Service (NACIS), Department of Neurosurgery, Royal Children's Hospital, Melbourne, VIC, Australia.
Brain Struct Funct. 2024 Jan;229(1):151-159. doi: 10.1007/s00429-023-02718-8. Epub 2023 Nov 20.
Myelination of human brain white matter (WM) continues into adulthood following birth, facilitating connection within and between brain networks. In vivo MRI studies using diffusion weighted imaging (DWI) suggest microstructural properties of brain WM increase over childhood and adolescence. Although DWI metrics, such as fractional anisotropy (FA), could reflect axonal myelination, they are not specific to myelin and could also represent other elements of WM microstructure, for example, fibre architecture, axon diameter and cell swelling. Little work exists specifically examining myelin development. The T1w/T2w ratio approach offers an alternative non-invasive method of estimating brain myelin. The approach uses MRI scans that are routinely part of clinical imaging and only require short acquisition times. Using T1w/T2w ratio maps from three waves of the Neuroimaging of the Children's Attention Project (NICAP) [N = 95 (208 scans); 44% female; ages 9.5-14.20 years] we aimed to investigate the developmental trajectories of brain white matter myelin in children as they enter adolescence. We also aimed to investigate whether longitudinal changes in myelination of brain WM differs between biological sex. Longitudinal regression modelling suggested non-linear increases in WM myelin brain wide. A positive parabolic, or U-shaped developmental trajectory was seen across 69 of 71 WM tracts modelled. At a corrected level, no significant effect for sex was found. These findings build on previous brain development research by suggesting that increases in brain WM microstructure from childhood to adolescence could be attributed to increases in myelin.
人类大脑白质（WM）的髓鞘形成在出生后仍持续到成年期，这有助于大脑网络内部和之间的连接。使用扩散加权成像（DWI）的活体 MRI 研究表明，儿童期和青春期大脑 WM 的微观结构特性增加。尽管 DWI 指标，如分数各向异性（FA），可以反映轴突髓鞘形成，但它们不是髓鞘特异性的，也可以代表 WM 微观结构的其他元素，例如纤维结构、轴突直径和细胞肿胀。很少有专门研究髓鞘发育的工作。T1w/T2w 比值方法提供了一种估计大脑髓鞘的替代非侵入性方法。该方法使用 MRI 扫描，这些扫描通常是临床成像的一部分，仅需要短的采集时间。使用儿童注意力项目的神经影像学（NICAP）的三个波次的 T1w/T2w 比值图（N = 95（208 次扫描）；44%为女性；年龄 9.5-14.20 岁），我们旨在研究儿童进入青春期时大脑白质髓鞘的发育轨迹。我们还旨在研究大脑 WM 髓鞘的纵向变化是否在生物学性别之间存在差异。纵向回归模型表明，大脑 WM 广泛的髓鞘呈非线性增加。在所建模的 71 个 WM 束中有 69 个显示出正抛物线或 U 形发育轨迹。在经过校正的水平上，未发现性别存在显著影响。这些发现通过表明从儿童期到青春期大脑 WM 微观结构的增加可以归因于髓鞘的增加，为以前的大脑发育研究提供了补充。
