Analysis of a large fMRI cohort: Statistical and methodological issues for group analyses
Analysis of a large fMRI cohort: Statistical and methodological issues for group analyses
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DOI：
10.1016/j.neuroimage.2006.11.054
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发表时间：
2007-03-01
期刊：
影响因子：
5.7
通讯作者：
Poline, Jean-Baptiste
中科院分区：
文献类型：
--
作者：
Thirion, Bertrand;Pinel, Philippe;Poline, Jean-Baptiste
团体功能磁共振成像研究的目的是将任务或刺激的对比与区域大脑活动的增加联系起来。这些研究通常涉及 10 至 16 名受试者。使用效应的受试者变异性（随机效应分析）来评估平均区域活动统计显着性。由于纳入的受试者数量相对较少，这些分析的敏感性和可靠性值得怀疑且难以调查。在这项工作中，我们使用了大量的主题（超过 80 个）来调查这个问题。我们利用这个大群体来研究受试者间活动的统计特性，并重点关注通过引导的可重复性的概念。我们提出了简单但重要的方法论问题：从可靠性的角度来看，活动图是否存在最佳统计阈值？小组研究中应包括多少科目？应该首选什么方法进行推理？我们的结果表明，i）确实可以找到最佳阈值，并且比通常的多重比较阈值校正要低，ii）为了具有足够的可靠性，应将 20 名或更多受试者纳入功能神经影像研究中，X）非参数显着性评估应优先于参数方法，iv）簇级阈值比基于体素的阈值更可靠，v）混合效应测试比随机效应测试更可靠。此外，我们的研究表明，受试者间的变异性在团体研究相对较低的敏感性和可靠性中发挥着重要作用。 (c) 2006 Elsevier Inc. 保留所有权利。
The aim of group fMRI studies is to relate contrasts of tasks or stimuli to regional brain activity increases. These studies typically involve 10 to 16 subjects. The average regional activity statistical significance is assessed using the subject to subject variability of the effect (random effects analyses). Because of the relatively small number of subjects included, the sensitivity and reliability of these analyses is questionable and hard to investigate. In this work, we use a very large number of subject (more than 80) to investigate this issue. We take advantage of this large cohort to study the statistical properties of the inter-subject activity and focus on the notion of reproducibility by bootstrapping. We asked simple but important methodological questions: Is there, from the point of view of reliability, an optimal statistical threshold for activity maps? How many subjects should be included in group studies? What method should be preferred for inference? Our results suggest that i) optimal thresholds can indeed be found, and are rather lower than usual corrected for multiple comparison thresholds, ii) 20 subjects or more should be included in functional neuroimaging studies in order to have sufficient reliability, X) non-parametric significance assessment should be preferred to parametric methods, iv) cluster-level thresholding is more reliable than voxel-based thresholding, and v) mixed effects tests are much more reliable than random effects tests. Moreover, our study shows that inter-subject variability plays a prominent role in the relatively low sensitivity and reliability of group studies. (c) 2006 Elsevier Inc. All rights reserved.