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Claudia Kirch, Karlsruhe Institute of Technology Print
Friday, 10 February 2012, 14:30 - 15:30

Claudia Kirch, Karlsruhe Institute of Technology

Evaluating stationarity via epidemic change-point alternatives for fMRI data

Abstract:Functional magnetic 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 non-stationarities 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.

Location: Plaine - Bâtiment NO - 9ème étage - Salle des Professeurs.
Contact: Jacqueline Douilly, This e-mail address is being protected from spam bots, you need JavaScript enabled to view it