ALFF outside the brain

Submitted by Jacky on Tue, 11/15/2011 - 08:49

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.

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Submitted by ZangYF on Wed, 11/16/2011 - 19:36 Permalink

Re: ALFF outside

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.