In hindsight, I had a very good hint here:
++ 5519 voxels in ROI
++ 43959 voxels in atlas-resampled mask
I think I did not realize that ROI and mask refer to basically the same thing, and that the ratio of the two numbers is almost exactly 8, which strongly suggests resampling to twice the resolution.
I think I am going to register all three ARM atlases to my AFNI and, to avoid confusion, give them meaningful names like ARMfh025, ARM05, and ARM025. Am I correct that this (including unregistering the ARM name for the large-FOV/0.25 mm atlas) can be done by editing the CustomAtlases.niml file?
