PNAS：研究揭示人脑网络中枢节点生理基础

日前，北京师范大学认知神经科学与学习国家重点实验室贺永课题组和美国国立卫生研究院药物成瘾研究所杨一鸿教授团队，通过功能连接与脑血流的相关性研究，揭示了人脑功能网络中枢节点的生理基础。相关研究成果近日在线发表于美国《国家科学院院刊》（PNAS）。

“人脑是自然界中最复杂的系统之一。人脑功能网络中的绝大多数脑节点只有少数连接，而少数节点却拥有非常多的连接，这些拥有连接数较多的节点被称为脑网络的中枢节点。”贺永在接受《中国科学报》记者采访时提到，正如交通网络中的枢纽一样，人脑网络的中枢节点对不同脑区间的信息传输起着关键作用，但学界对其与人脑生理指标之间的关系仍知之甚少。

为此，贺永及同事采用多模态功能影像数据，揭示了大脑网络中枢节点的功能连接和脑血流量的关联规律。通过实验，该团队发现，大脑功能网络的中枢节点主要分布于默认网络（内侧额顶皮层）、脑岛和视觉皮层，并显示出和静息态下的局部脑血流（rCBF）显著的空间相关性。

研究还将大脑功能网络分为四个主要模块：默认网络、执行控制、感觉运动和视觉模块。其中，连接强度（FCS）和rCBF在默认和执行控制模块中表现出比视觉和感觉运动模块更高的空间相关性，而且在执行工作记忆任务时，两者也同样有相关性，并随着任务强度的增加而显著增强。

业内专家表示，该研究阐释了人脑功能连接组的代谢和生理基础，对进一步加深理解人脑认知加工的神经机制，揭示人脑正常发育、老化和神经精神疾病（如阿尔茨海默病、抑郁症）中脑功能连接组的变化，以及研究脑疾病早期诊断的影像标记物等临床问题具有重要潜在价值。

与人脑相关的拓展阅读：

• 美国正式开展人脑工程计划
• Cell Stem Cell：老鼠植入人脑细胞后变聪明
• Neuron：李卫东等揭示精神分裂症基因对人脑影响机制
• Science：美国研究人员揭示人脑神经纤维排列方式
更多信息请点击：有关人脑更多资讯 

doi:10.1016/j.cell.2011.10.

Coupling of functional connectivity and regional cerebral blood flow reveals a physiological basis for network hubs of the human brain
 

Xia Liang,Qihong Zou,Yong He,and Yihong Yang.

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.