When we have been running our fmri analyses in FEAT, we have observed that when we do second-level a group mask seems to be created which is based on where all the subjects have a voxel in the epi image. A challenge with this that we have experienced it is that if for example one of the subjects has an especially large signal loss in the entorhinal cortex due to susceptibility artifacts this will result in seemingly no signal change in that region for the different conditions, even though it indeed was relatively large signal changes in the entorhinal cortex as we observed when we increased the size of the group mask. My question is the reason why the analysis in FEAT is masked the way it is? Any feedback would be highly appreciated.
Best regards
Hallvard Røe Evensmoen
Postdoctoral research fellow
Department of Neuroscience
Norwegian University of Science and Technology
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