EVALUATING STATIONARITY VIA CHANGE-POINT ALTERNATIVES WITH APPLICATIONS TO FMRI DATA
EVALUATING STATIONARITY VIA CHANGE-POINT ALTERNATIVES WITH APPLICATIONS TO FMRI DATA
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DOI：
10.1214/12-aoas565
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发表时间：
2012-12-01
影响因子：
1.8
通讯作者：
Kirch, Claudia
中科院分区：
文献类型：
--
作者：
Aston, John A. D.;Kirch, Claudia
功能性磁共振成像（fMRI）现在是研究大脑的一种成熟技术。然而，在许多情况下，例如当在静止状态下采集数据时，很难知道数据是否真正静止或是否发生了电平偏移。为此，在功能数据序列中的变点检测检查的功能观察是依赖性的，并且需要从多个主题的变点的分布。特别令人感兴趣的是变点是流行性变化的情况-发生变化，然后观察值在稍后的时间返回到基线。协方差可以分解为张量积的情况下，被认为是特别注意检测的功率分析。这在fMRI的应用中是感兴趣的，其中三维图像的全协方差结构的估计在计算上是不可行的。使用所开发的方法，静息状态的功能磁共振成像数据进行大型研究，以确定是否进行静息扫描的受试者有nonstationarities存在于他们的时间过程。据发现，相当大比例的研究对象是不固定的。这些科目的变点分布是经验确定的，以及其理论特性检查。
Functionalmagnetic resonance imaging (fMRI) is now a well-established technique for studying the brain. However, in many situations, such as when data are acquired in a resting state, it is difficult to know whether the data are truly stationary or if level shifts have occurred. To this end, change-point detection in sequences of functional data is examined where the functional observations are dependent and where the distributions of change-points from multiple subjects are required. Of particular interest is the case where the change-point is an epidemic change-a change occurs and then the observations return to baseline at a later time. The case where the covariance can be decomposed as a tensor product is considered with particular attention to the power analysis for detection. This is of interest in the application to fMRI, where the estimation of a full covariance structure for the three-dimensional image is not computationally feasible. Using the developed methods, a large study of resting state fMRI data is conducted to determine whether the subjects undertaking the resting scan have nonstationarities present in their time courses. It is found that a sizeable proportion of the subjects studied are not stationary. The change-point distribution for those subjects is empirically determined, as well as its theoretical properties examined.