Cho Chloe, Chamberland Maxime, Rheault Francois, Moyer Daniel, Landman Bennett A, Schilling Kurt G
Department of Biomedical Engineering, Vanderbilt University, Nashville, Tennessee, USA.
Department of Mathematics and Computer Science, Eindhoven University of Technology, Eindhoven, the Netherlands.
Hum Brain Mapp. 2025 Jun 1;46(8):e70255. doi: 10.1002/hbm.70255.
Short association fibers (SAFs) in the superficial white matter play a key role in mediating local cortical connections but have not been well-studied as innovations in whole-brain diffusion tractography have only recently been developed to study superficial white matter. Characterizing SAFs and their relationship to long-range white matter tracts is crucial to advance our understanding of neurodevelopment during the period from childhood to young adulthood. This study aims to (1) map SAFs in relation to long-range white matter tracts, (2) characterize typical neurodevelopmental changes across these white matter pathways, and (3) investigate the relationship between microstructural changes in SAFs and long-range white matter tracts. Leveraging a cohort of 616 participants ranging in age from 5.6 to 21.9 years old, we performed quantitative diffusion tractography and advanced diffusion modeling with diffusion tensor imaging (DTI) and neurite orientation dispersion and density imaging (NODDI). Robust linear regression models were applied to analyze microstructural features, including fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD), radial diffusivity (RD), intracellular volume fraction (ICVF), isotropic volume fraction (ISOVF), and orientation dispersion index (ODI). Our results reveal that both SAFs and long-range tracts exhibit similar overall developmental patterns, characterized by negative associations of MD, AD, and RD with age and positive associations of FA, ICVF, ISOVF, and ODI with age. Notably, FA, AD, and ODI exhibit significant differences between SAFs and long-range tracts, suggesting distinct neurodevelopmental trajectories between superficial and deep white matter. In addition, significant differences were found in MD, RD, and ICVF between males and females, highlighting variations in neurodevelopment. This normative study provides insights into typical microstructural changes of SAFs and long-range white matter tracts during development, laying a foundation for future research to investigate atypical development and dysfunction in disease pathology.
浅表层白质中的短联合纤维（SAFs）在介导局部皮质连接中起关键作用，但由于全脑扩散张量成像技术直到最近才被开发用于研究浅表层白质，因此对其研究尚不充分。明确SAFs及其与长程白质束的关系对于增进我们对儿童期至青年期神经发育的理解至关重要。本研究旨在：（1）绘制与长程白质束相关的SAFs图谱；（2）描述这些白质通路典型的神经发育变化；（3）研究SAFs微观结构变化与长程白质束之间的关系。我们利用一个由616名年龄在5.6岁至21.9岁之间的参与者组成的队列，采用扩散张量成像（DTI）和神经突方向离散度与密度成像（NODDI）进行了定量扩散张量成像和高级扩散建模。应用稳健线性回归模型分析微观结构特征，包括分数各向异性（FA）、平均扩散率（MD）、轴向扩散率（AD）、径向扩散率（RD）、细胞内体积分数（ICVF）、各向同性体积分数（ISOVF）和方向离散度指数（ODI）。我们的结果显示，SAFs和长程束均呈现出相似的整体发育模式，其特征为MD、AD和RD与年龄呈负相关，FA、ICVF、ISOVF和ODI与年龄呈正相关。值得注意的是，SAFs和长程束在FA、AD和ODI方面存在显著差异，表明浅表层和深层白质的神经发育轨迹不同。此外，男性和女性在MD、RD和ICVF方面存在显著差异，突出了神经发育的性别差异。这项规范性研究为深入了解发育过程中SAFs和长程白质束的典型微观结构变化提供了见解，为未来研究疾病病理学中的非典型发育和功能障碍奠定了基础。
