What is it about?
This method shows time points where group signals are higher or lower than a baseline, or differ between groups. The approach is applicable to physiologic challenges where a baseline is followed by one or more trials. For example, an autonomic test might involve a 1 minute baseline, an 18 second Valsalva maneuver repeated four times at 1 minute intervals, and a 30 second recovery. Physiologic signals could include fMRI in one location or heart rate. For many physiologic protocols, the timing of exactly when a response occurs is important. The analysis shows time points when mean group signals are differ from baseline or other groups, controlling for repeated measures and the random effect of "subject"; in other words, the results account for for the lack of independence between repeated measures and individual subject variation.
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Why is it important?
The method is useful for analyzing complex responses that don't follow a simple "on/off" pattern. For fMRI, we use this as a complement to standard boxcar analyses (as with SPM software).
Perspectives
We found in our research of fMRI and heart rate responses to autonomic challenges that we needed a method to identify exactly when the heart rate or fMRI signal changed 1) from baseline, and 2) between-groups.
Dr Paul M Macey
University of California Los Angeles
Read the Original
This page is a summary of: Detecting variable responses within fMRI time-series of volumes-of-interest using repeated measures ANOVA, F1000Research, April 2016, Faculty of 1000, Ltd.,
DOI: 10.12688/f1000research.8252.1.
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