National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD 20892, USA.
Neuroimage. 2011 Aug 1;57(3):908-17. doi: 10.1016/j.neuroimage.2011.05.024. Epub 2011 May 14.
Brain networks appear to have few and well localized regions with high functional connectivity density (hubs) for fast integration of neural processing, and their dysfunction could contribute to neuropsychiatric diseases. However the variability in the distribution of these brain hubs is unknown due in part to the overwhelming computational demands associated to their localization. Recently we developed a fast algorithm to map the local functional connectivity density (lFCD). Here we extend our method to map the global density (gFDC) taking advantage of parallel computing. We mapped the gFCD in the brain of 1031 subjects from the 1000 Functional Connectomes project and show that the strongest hubs are located in regions of the default mode network (DMN) and in sensory cortices, whereas subcortical regions exhibited the weakest hubs. The strongest hubs were consistently located in ventral precuneus/cingulate gyrus (previously identified by other analytical methods including lFCD) and in primary visual cortex (BA 17/18), which highlights their centrality to resting connectivity networks. In contrast and after rescaling, hubs in prefrontal regions had lower gFCD than lFCD, which suggests that their local functional connectivity (as opposed to long-range connectivity) prevails in the resting state. The power scaling of the probability distribution of gFCD hubs (as for lFCD) was consistent across research centers further corroborating the "scale-free" topology of brain networks. Within and between-subject variability for gFCD were twice than that for lFCD (20% vs. 12% and 84% vs. 34%, respectively) suggesting that gFCD is more sensitive to individual differences in functional connectivity.
大脑网络似乎具有少数几个功能连接密度高（枢纽）的区域，这些区域有利于神经处理的快速整合，其功能障碍可能导致神经精神疾病。然而，由于与定位相关的计算需求过大，这些大脑枢纽的分布变化尚不清楚。最近，我们开发了一种快速算法来绘制局部功能连接密度（lFCD）图。在这里，我们利用并行计算将我们的方法扩展到绘制全局密度（gFCD）图。我们对来自 1000 个功能连接组学项目的 1031 名受试者的大脑进行了 gFCD 映射，并发现最强的枢纽位于默认模式网络（DMN）和感觉皮层的区域，而皮质下区域的枢纽则较弱。最强的枢纽始终位于腹侧楔前叶/扣带回（以前通过包括 lFCD 在内的其他分析方法确定）和初级视觉皮层（BA17/18），这突出了它们在静息连接网络中的中心地位。相比之下，在进行缩放后，前额叶区域的枢纽的 gFCD 比 lFCD 低，这表明它们的局部功能连接（而不是长程连接）在静息状态下占主导地位。gFCD 枢纽概率分布的幂律缩放（与 lFCD 相同）在各个研究中心都一致，进一步证实了大脑网络的“无标度”拓扑。gFCD 的组内和组间变异性是 lFCD 的两倍（分别为 20%对 12%和 84%对 34%），这表明 gFCD 对功能连接的个体差异更敏感。
