Hi Linda,
Catching up here, sorry, thanks for the reminder.
Using afni_proc.py is merely a convenience for
single subject analysis. It really just writes
a processing script that still uses a both
surface and volumetric programs to do the work.
Volumetric data gets mapped to the surface using
3dVol2Surf just after volumetric registration.
So time series data gets mapped to the surface.
Then blurring, scaling and regression can be
done on the surface. After all of that, beta
weights and t-stats are on the surface, and one
is ready for a group analysis.
Most AFNI programs that have no spatial concerns
(e.g. 3dcalc, 3dDeconvolve, 3dMVM, 3dFDR) should
not care whether data is on the surface or in
the volume. They worth the same.
Clustering and blurring are spatial computations,
so 3dmerge and 3dClustSim would not be appropriate
for surface data, for example.
Look at a surface analysis script to see what it
is doing. One example is
s13.proc.FT.surf.
- rick