Neuroimaging Research Branch, National Institute on Drug Abuse, National Institutes of Health, Baltimore, MD 21224, USA.
Proc Natl Acad Sci U S A. 2013 Jan 29;110(5):1929-34. doi: 10.1073/pnas.1214900110. Epub 2013 Jan 14.
Human brain functional networks contain a few densely connected hubs that play a vital role in transferring information across regions during resting and task states. However, the relationship of these functional hubs to measures of brain physiology, such as regional cerebral blood flow (rCBF), remains incompletely understood. Here, we used functional MRI data of blood-oxygenation-level-dependent and arterial-spin-labeling perfusion contrasts to investigate the relationship between functional connectivity strength (FCS) and rCBF during resting and an N-back working-memory task. During resting state, functional brain hubs with higher FCS were identified, primarily in the default-mode, insula, and visual regions. The FCS showed a striking spatial correlation with rCBF, and the correlation was stronger in the default-mode network (DMN; including medial frontal-parietal cortices) and executive control network (ECN; including lateral frontal-parietal cortices) compared with visual and sensorimotor networks. Moreover, the relationship was connection-distance dependent; i.e., rCBF correlated stronger with long-range hubs than short-range ones. It is notable that several DMN and ECN regions exhibited higher rCBF per unit connectivity strength (rCBF/FCS ratio); whereas, this index was lower in posterior visual areas. During the working-memory experiment, both FCS-rCBF coupling and rCBF/FCS ratio were modulated by task load in the ECN and/or DMN regions. Finally, task-induced changes of FCS and rCBF in the lateral-parietal lobe positively correlated with behavioral performance. Together, our results indicate a tight coupling between blood supply and brain functional topology during rest and its modulation in response to task demands, which may shed light on the physiological basis of human brain functional connectome.
人脑功能网络包含少数几个密集连接的枢纽，这些枢纽在静息和任务状态下在区域间传递信息方面起着至关重要的作用。然而，这些功能枢纽与大脑生理学的测量指标之间的关系，如局部脑血流(rCBF)，仍然不完全清楚。在这里，我们使用血氧水平依赖功能磁共振成像数据和动脉自旋标记灌注对比来研究静息状态和 N 回工作记忆任务期间功能连接强度(FCS)与 rCBF 之间的关系。在静息状态下，确定了具有较高 FCS 的功能脑枢纽，主要位于默认模式、脑岛和视觉区域。FCS 与 rCBF 之间存在显著的空间相关性，并且在默认模式网络(DMN；包括内侧额顶叶皮层)和执行控制网络(ECN；包括外侧额顶叶皮层)中与视觉和感觉运动网络相比相关性更强。此外，这种关系与连接距离有关；即，rCBF 与长程枢纽的相关性比短程枢纽更强。值得注意的是，DMN 和 ECN 的几个区域表现出每单位连接强度更高的 rCBF(rCBF/FCS 比)；然而，这个指数在后部视觉区域较低。在工作记忆实验中，FCS-rCBF 耦合和 rCBF/FCS 比在 ECN 和/或 DMN 区域都受到任务负荷的调节。最后，外侧顶叶叶的任务诱导的 FCS 和 rCBF 的变化与行为表现呈正相关。总之，我们的结果表明，在静息和响应任务需求的调节期间，血液供应和大脑功能拓扑之间存在紧密的耦合，这可能为人类大脑功能连接组学的生理基础提供了一些启示。
