Thanks a lot for this Gang,
I have some additional (related) questions that I cannot easily address.

I just would like to run an SCV to further explore and characterize my results (using small preregistered ROIs, which I found as being significantly involved in the task when running some t-tests on the averaged beta weights as well as when looking at the results from the whole brain). To do this, I was applying a 3dttest++ and 3dClustSim to each of the small ROIs and looking at the clusters that survive an initial uncorrected threshold of .001 or .005, but I didn't do anything with the FWHM, which turns to be very relevant in voxel-wise analysis in small regions. I have, however, some doubts about what I did so far:

- How can I implement FWHM in my analysis? More specifically, in the second-level analysis, I should use the acf obtained from the mean group (3dttest++) or that one at individual level (from 3dDeconvolve)? (I am very new to afni, and I am still learning how to program). I am using 3dDeconvolve and 3dREMLfit for my first-level analysis.

- Is it correct to use ClustSim in a small volume (e.g. VTA, which has 40 voxels)? I would think that a peak-level analysis (as SVC in SPM) would be more appropriate here. If this is correct, wherein the output I need to look? I guess I should look at the peak of the cluster and check with the alpha value that comes from the analysis with the FWHM?

Thanks a lot in advance for your kind help!

Silvia