Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States of America.
PLoS One. 2012;7(12):e49847. doi: 10.1371/journal.pone.0049847. Epub 2012 Dec 5.
Resting-state functional MRI (rs-fMRI) has emerged as a powerful tool for investigating brain functional connectivity (FC). Research in recent years has focused on assessing the reliability of FC across younger subjects within and between scan-sessions. Test-retest reliability in resting-state functional connectivity (RSFC) has not yet been examined in older adults. In this study, we investigated age-related differences in reliability and stability of RSFC across scans. In addition, we examined how global signal regression (GSR) affects RSFC reliability and stability. Three separate resting-state scans from 29 younger adults (18-35 yrs) and 26 older adults (55-85 yrs) were obtained from the International Consortium for Brain Mapping (ICBM) dataset made publically available as part of the 1000 Functional Connectomes project www.nitrc.org/projects/fcon_1000. 92 regions of interest (ROIs) with 5 cubic mm radius, derived from the default, cingulo-opercular, fronto-parietal and sensorimotor networks, were previously defined based on a recent study. Mean time series were extracted from each of the 92 ROIs from each scan and three matrices of z-transformed correlation coefficients were created for each subject, which were then used for evaluation of multi-scan reliability and stability. The young group showed higher reliability of RSFC than the old group with GSR (p-value = 0.028) and without GSR (p-value <0.001). Both groups showed a high degree of multi-scan stability of RSFC and no significant differences were found between groups. By comparing the test-retest reliability of RSFC with and without GSR across scans, we found significantly higher proportion of reliable connections in both groups without GSR, but decreased stability. Our results suggest that aging is associated with reduced reliability of RSFC which itself is highly stable within-subject across scans for both groups, and that GSR reduces the overall reliability but increases the stability in both age groups and could potentially alter group differences of RSFC.
静息态功能磁共振成像（rs-fMRI）已成为研究大脑功能连接（FC）的有力工具。近年来的研究集中于评估年轻受试者在扫描内和扫描间的 FC 可靠性。在老年人中，尚未对静息态功能连接（RSFC）的测试重测信度进行研究。在这项研究中，我们研究了不同年龄组之间扫描中 RSFC 的可靠性和稳定性差异。此外，我们还研究了全局信号回归（GSR）如何影响 RSFC 的可靠性和稳定性。从国际脑映射联合会（ICBM）数据集获得了 29 名年轻成年人（18-35 岁）和 26 名老年人（55-85 岁）的三个独立静息态扫描。该数据集作为 1000 个功能连接组项目的一部分公开提供www.nitrc.org/projects/fcon_1000。基于最近的一项研究，从默认的扣带 - 脑岛、额顶叶和感觉运动网络中定义了 92 个感兴趣区域（ROI），每个 ROI 的半径为 5 立方毫米。从每个扫描的每个 ROI 中提取平均时间序列，并为每个受试者创建三个 z 变换相关系数矩阵，然后用于评估多扫描可靠性和稳定性。使用 GSR（p 值=0.028）和不使用 GSR（p 值<0.001）时，年轻组的 RSFC 可靠性均高于老年组。两组的 RSFC 多扫描稳定性均较高，两组之间无显着差异。通过比较扫描间 GSR 有无 GSR 对 RSFC 测试重测信度的影响，我们发现两组中不使用 GSR 的可靠连接比例均显着较高，但稳定性降低。我们的结果表明，衰老与 RSFC 的可靠性降低有关，两组之间在扫描内的 RSFC 均高度稳定，而 GSR 降低了整体可靠性，但增加了稳定性，并可能改变 RSFC 的组间差异。
