ALFF outside the brain

Submitted by Jacky on
I used the standard procedure:Smooth FWHM: [8 8 8];Detrend, Filter, ALFF; And smooth the mALFF with FWHM [8 8 8], but the ALFF is outside the brain and the t values look crazy. How come? TR=2s.

It seems that you smoothed twice. I would suggest only once. Due to spatial smoothing, the intensity of voxels near the brain boundary will be smoothed. If the value of a voxel immediately outside the brain is 0, it will get a value near the mean of neighboring voxels.