Qin Yuan-Yuan, Li Ya-Peng, Zhang Shun, Xiong Ying, Guo Lin-Ying, Yang Shi-Qi, Yao Yi-Hao, Li Wei, Zhu Wen-Zhen
Department of Radiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430030, China.
Chin Med J (Engl). 2015 Mar 5;128(5):602-9. doi: 10.4103/0366-6999.151654.
Previous studies have indicated that the cognitive deficits in patients with Alzheimer's disease (AD) may be due to topological deteriorations of the brain network. However, whether the selection of a specific frequency band could impact the topological properties is still not clear. Our hypothesis is that the topological properties of AD patients are also frequency-specific.
Resting state functional magnetic resonance imaging data from 10 right-handed moderate AD patients (mean age: 64.3 years; mean mini mental state examination [MMSE]: 18.0) and 10 age and gender-matched healthy controls (mean age: 63.6 years; mean MMSE: 28.2) were enrolled in this study. The global efficiency, the clustering coefficient (CC), the characteristic path length (CpL), and "small-world" property were calculated in a wide range of thresholds and averaged within each group, at three different frequency bands (0.01-0.06 Hz, 0.06-0.11 Hz, and 0.11-0.25 Hz).
At lower-frequency bands (0.01-0.06 Hz, 0.06-0.11 Hz), the global efficiency, the CC and the "small-world" properties of AD patients decreased compared to controls. While at higher-frequency bands (0.11-0.25 Hz), the CpL was much longer, and the "small-world" property was disrupted in AD, particularly at a higher threshold. The topological properties changed with different frequency bands, suggesting the existence of disrupted global and local functional organization associated with AD.
This study demonstrates that the topological alterations of large-scale functional brain networks in AD patients are frequency dependent, thus providing fundamental support for optimal frequency selection in future related research.
先前的研究表明，阿尔茨海默病（AD）患者的认知缺陷可能归因于脑网络的拓扑结构退化。然而，特定频段的选择是否会影响拓扑特性仍不清楚。我们的假设是，AD患者的拓扑特性也是频率特异性的。
本研究纳入了10名右利手的中度AD患者（平均年龄：64.3岁；平均简易精神状态检查表[MMSE]：18.0）和10名年龄及性别匹配的健康对照者（平均年龄：63.6岁；平均MMSE：28.2）的静息态功能磁共振成像数据。在三个不同频段（0.01 - 0.06Hz、0.06 - 0.11Hz和0.11 - 0.25Hz）的广泛阈值范围内计算全局效率、聚类系数（CC）、特征路径长度（CpL）和“小世界”特性，并在每组内进行平均。
在较低频段（0.01 - 0.06Hz、0.06 - 0.11Hz），与对照组相比，AD患者的全局效率、CC和“小世界”特性降低。而在较高频段（0.11 - 0.25Hz），AD患者的CpL更长，且“小世界”特性被破坏，尤其是在较高阈值时。拓扑特性随不同频段而变化，表明存在与AD相关的全局和局部功能组织破坏。
本研究表明，AD患者大脑大规模功能网络的拓扑改变是频率依赖性的，从而为未来相关研究中的最佳频率选择提供了基础支持。
