Hi Mahen,
Note that removing baseline and motion is a separate issue
from converting to percent signal change. It is not necessary
to convert to PSC to use 3dSynthesize to remove baseline and
motion.
Do you need PSC for the subsequent analysis?
To convert to PSC, divide by the constant baseline term and
multiply by 100. As mentioned above, what you subtract out is a
different story. Note that option 2 is not quite what you want,
as subtracting the baseline would leave you with a mean of 0.
In any case, it is presumably the constant baseline term that you
want to scale by (new = old * 100 / baseline). There is also the
question of scaling per run or using one scalar across all runs.
We scale per run by default (and by the mean, not the baseline,
but that should only make a very small difference).
---
On the flip side, if you want the data scaled after 3dDeconvolve,
why not just have afni_proc.py do it to begin with?
Though there is still the question of whether scaling is needed
or desired for the next step.
- rick
