Dear Expert,
In SPM 5 when I specify model at the 1st level I can select an explicit
mask. I select smwc1_subxx.img as explicit mask. I obtain this image with
segmentation (mwc1_subxx.img) and after I smooth it with the same FWHM (8
mm) as EPI (voxel size of EPI normalization equal to 2x2x2). Also
segmentation normalizes with voxel size equal to 2x2x2.
Following this procedure I expect to model only gray matter activations and
also I expect to have more statistical power when I apply FWE or FDR
correction (image should have less voxel, only gray matter voxel). Is this
true?
Is a good or bad idea using an explicit mask of gray matter?
Any suggesion is appreciated.
Thank you.
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