A resilient, low-frequency, small-world human brain functional network with highly connected association cortical hubs
A resilient, low-frequency, small-world human brain functional network with highly connected association cortical hubs
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DOI：
10.1523/jneurosci.3874-05.2006
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发表时间：
2006-01-04
影响因子：
5.3
通讯作者：
Bullmore, ET
中科院分区：
文献类型：
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作者：
Achard, S;Salvador, R;Bullmore, ET
小世界性质已经在许多复杂网络中得到了证明。在这里，我们应用离散小波变换的功能性磁共振成像（fMRI）的时间序列，获得健康志愿者在休息状态下，估计频率依赖的相关矩阵表征90皮质和皮质下区域之间的功能连接。在对小波相关矩阵进行阈值处理以创建脑功能网络的无向图之后，我们发现稀疏连接的小世界拓扑结构在低频区间0.03-0.06 Hz中最突出。全球平均路径长度（2.49）大致相当于一个可比的随机网络，而聚类（0.53）是两倍大，类似的参数已报告的网络解剖连接在猕猴皮层。人类的功能网络是由一个高度连接的枢纽新皮层核心占主导地位，并有一个指数截断幂律度分布。枢纽包括最近进化的异模态关联皮层区域，与其他区域有长距离连接，以及单峰关联和初级皮层的更多集团连接区域;边缘和边缘区域在拓扑学上更外围。该网络比可比的无标度网络更能抵御针对其枢纽的攻击，但对随机错误的抵御能力大致相同。我们的结论是，相关的，低频振荡在人类功能磁共振成像数据有一个小世界的架构，可能反映了底层的解剖连接的皮层。由于这个网络的主要枢纽对认知至关重要，它的缓慢动态可以为隔离和分布式信息处理提供生理基础。
Small-world properties have been demonstrated for many complex networks. Here, we applied the discrete wavelet transform to functional magnetic resonance imaging (fMRI) time series, acquired from healthy volunteers in the resting state, to estimate frequency-dependent correlation matrices characterizing functional connectivity between 90 cortical and subcortical regions. After thresholding the wavelet correlation matrices to create undirected graphs of brain functional networks, we found a small-world topology of sparse connections most salient in the low-frequency interval 0.03-0.06 Hz. Global mean path length (2.49) was approximately equivalent to a comparable random network, whereas clustering (0.53) was two times greater; similar parameters have been reported for the network of anatomical connections in the macaque cortex. The human functional network was dominated by a neocortical core of highly connected hubs and had an exponentially truncated power law degree distribution. Hubs included recently evolved regions of the heteromodal association cortex, with long-distance connections to other regions, and more cliquishly connected regions of the unimodal association and primary cortices; paralimbic and limbic regions were topologically more peripheral. The network was more resilient to targeted attack on its hubs than a comparable scale-free network, but about equally resilient to random error. We conclude that correlated, low-frequency oscillations in human fMRI data have a small-world architecture that probably reflects underlying anatomical connectivity of the cortex. Because the major hubs of this network are critical for cognition, its slow dynamics could provide a physiological substrate for segregated and distributed information processing.