University of California, San Diego, Department of Psychiatry, 9500 Gilman Drive # 151B, La Jolla, CA 92093-151B, USA.
Brain Res. 2010 Apr 23;1327:38-46. doi: 10.1016/j.brainres.2010.02.066. Epub 2010 Mar 2.
Late adolescence is comprised of considerable developmental transitions, though brain maturational changes during this period are subtle and difficult to quantitatively evaluate from standard brain imaging acquisitions. To date, primarily cross-sectional studies have characterized typical developmental changes during adolescence, but these processes need further description within a longitudinal framework.
To assess the developmental trajectory of typical white matter development, we examined 22 healthy adolescents with serial diffusion tensor images (DTI) collected at a mean age of 17.8 years and 16-months later. Diffusion parameters fractional anisotropy, and mean, radial, and axial diffusivity were subjected to whole-brain voxelwise time point comparisons using tract-based spatial statistics.
At follow-up, adolescents showed a significant change (>or=153 contiguous voxels each at p<0.01) in diffusion properties, including in bilateral superior longitudinal fasciculi, superior corona radiata, anterior thalamic radiations, and posterior limb of the internal capsule. Overall, correlations with cognitive performances suggested behavioral improvement corresponding with white matter changes.
These longitudinal DTI findings support continued microstructural change in white matter during late adolescence, and suggest ongoing refinement of projection and association fibers into early adulthood.
青春期后期包含了许多发展上的转变，尽管在此期间大脑的成熟变化很细微，难以从标准的脑影像采集来进行定量评估。迄今为止，主要的横断面研究已经描述了青春期期间的典型发展变化，但这些过程需要在纵向框架内进一步描述。
为了评估典型的白质发育的发展轨迹，我们检查了 22 名健康的青少年，他们在平均年龄为 17.8 岁和 16 个月后分别进行了多次弥散张量成像（DTI）采集。使用基于束的空间统计学，对弥散参数各向异性分数、平均弥散度、径向弥散度和轴向弥散度进行了全脑体素的时间点比较。
在随访时，青少年在弥散特性上表现出显著的变化（p<0.01，每个变化超过 153 个连续体素），包括双侧上纵束、上放射冠、前丘脑辐射和内囊后肢。总的来说，与认知表现的相关性表明，行为改善与白质变化相对应。
这些纵向 DTI 的发现支持在青春期后期白质中持续的微观结构变化，并表明投射和联合纤维在进入成年早期时仍在不断细化。
