Li Gang, Liu Tianming, Ni Dong, Lin Weili, Gilmore John H, Shen Dinggang
Department of Radiology and BRIC, University of North Carolina at Chapel Hill, North Carolina.
Department of Computer Science and Bioimaging Research Center, The University of Georgia, Athens, Georgia.
Hum Brain Mapp. 2015 Dec;36(12):5183-95. doi: 10.1002/hbm.23003. Epub 2015 Sep 29.
The intrinsic relationship between the convoluted cortical folding and the underlying complex whiter matter fiber connections has received increasing attention in current neuroscience studies. Recently, the axonal pushing hypothesis of cortical folding has been proposed to explain the finding that the axonal fibers (derived from diffusion tensor images) connecting to gyri are significantly denser than those connecting to sulci in both adult human and non-human primate brains. However, it is still unclear about the spatiotemporal patterns of the fiber density on the cortical surface of the developing infant brains from birth to 2 years of age, which is the most dynamic phase of postnatal brain development. In this paper, for the first time, we systemically characterized the spatial distributions and longitudinal developmental trajectories of the cortical fiber density in the first 2 postnatal years, via joint analysis of longitudinal structural and diffusion tensor imaging from 33 healthy infants. We found that the cortical fiber density increases dramatically in the first year and then keeps relatively stable in the second year. Moreover, we revealed that the cortical fiber density on gyral regions was significantly higher at 0, 1, and 2 years of age than that on sulcal regions in the frontal, temporal, and parietal lobes. Meanwhile, the cortical fiber density was strongly positively correlated with cortical thickness at several three-hinge junction regions of gyri. These results significantly advanced our understanding of the intrinsic relationship between the cortical folding, cortical thickness and axonal wiring during early postnatal stages.
在当前神经科学研究中，复杂的皮质折叠与潜在的复杂白质纤维连接之间的内在关系受到了越来越多的关注。最近，有人提出了皮质折叠的轴突推动假说，以解释在成年人类和非人类灵长类动物大脑中，连接脑回的轴突纤维（源自扩散张量成像）比连接脑沟的轴突纤维明显更密集这一发现。然而，对于出生至2岁的发育中婴儿大脑皮质表面纤维密度的时空模式仍不清楚，而这一阶段是出生后大脑发育最活跃的时期。在本文中，我们首次通过对33名健康婴儿的纵向结构和扩散张量成像进行联合分析，系统地描述了出生后前两年皮质纤维密度的空间分布和纵向发育轨迹。我们发现，皮质纤维密度在第一年急剧增加，然后在第二年保持相对稳定。此外，我们还发现，在额叶、颞叶和顶叶的脑回区域，0岁、1岁和2岁时的皮质纤维密度显著高于脑沟区域。同时，在脑回的几个三铰链连接区域，皮质纤维密度与皮质厚度呈强正相关。这些结果显著推进了我们对出生后早期阶段皮质折叠、皮质厚度和轴突布线之间内在关系的理解。
