Graduate Program in Biomedical Informatics, Stanford University School of Medicine, Stanford, CA 94304, USA.
Neuroimage. 2010 Aug 1;52(1):290-301. doi: 10.1016/j.neuroimage.2010.04.009. Epub 2010 Apr 10.
Functional and structural maturation of networks comprised of discrete regions is an important aspect of brain development. The default-mode network (DMN) is a prominent network which includes the posterior cingulate cortex (PCC), medial prefrontal cortex (mPFC), medial temporal lobes (MTL), and angular gyrus (AG). Despite increasing interest in DMN function, little is known about its maturation from childhood to adulthood. Here we examine developmental changes in DMN connectivity using a multimodal imaging approach by combining resting-state fMRI, voxel-based morphometry and diffusion tensor imaging-based tractography. We found that the DMN undergoes significant developmental changes in functional and structural connectivity, but these changes are not uniform across all DMN nodes. Convergent structural and functional connectivity analyses suggest that PCC-mPFC connectivity along the cingulum bundle is the most immature link in the DMN of children. Both PCC and mPFC also showed gray matter volume differences, as well as prominent macrostructural and microstructural differences in the dorsal cingulum bundle linking these regions. Notably, structural connectivity between PCC and left MTL was either weak or non-existent in children, even though functional connectivity did not differ from that of adults. These results imply that functional connectivity in children can reach adult-like levels despite weak structural connectivity. We propose that maturation of PCC-mPFC structural connectivity plays an important role in the development of self-related and social-cognitive functions that emerge during adolescence. More generally, our study demonstrates how quantitative multimodal analysis of anatomy and connectivity allows us to better characterize the heterogeneous development and maturation of brain networks.
功能和结构上成熟的离散区域网络是大脑发育的一个重要方面。默认模式网络（DMN）是一个突出的网络，包括后扣带回皮层（PCC）、内侧前额叶皮层（mPFC）、内侧颞叶（MTL）和角回（AG）。尽管人们对 DMN 功能的兴趣日益增加，但对其从儿童期到成年期的成熟过程知之甚少。在这里，我们通过结合静息态 fMRI、基于体素的形态测量和基于扩散张量成像的束追踪，使用多模态成像方法来检查 DMN 连接的发育变化。我们发现 DMN 在功能和结构连接方面经历了显著的发育变化，但这些变化并非在所有 DMN 节点上都是均匀的。收敛的结构和功能连接分析表明，沿扣带束的 PCC-mPFC 连接是儿童 DMN 中最不成熟的环节。PCC 和 mPFC 也显示出灰质体积差异，以及连接这些区域的背侧扣带束的明显宏观和微观结构差异。值得注意的是，儿童的 PCC 与左 MTL 之间的结构连接要么很弱，要么不存在，尽管功能连接与成人没有差异。这些结果表明，尽管结构连接较弱，儿童的功能连接仍能达到成人水平。我们提出，PCC-mPFC 结构连接的成熟在青春期出现的自我相关和社会认知功能的发展中起着重要作用。更一般地说，我们的研究表明，对解剖结构和连接的定量多模态分析如何使我们能够更好地描述大脑网络的异质发育和成熟。
