afni.nimh.nih.gov

Hi Rick,
afni_proc seems to use principal components (PCs) for CSF but what about WM? Why aren't components calculated for WM as well?
Also why are only 3 PCs included? Wouldn't it be better to calculate the number of PCs automatically based on their ability to explain variance in the dataset, as implemented here: [nipype.readthedocs.io] (using the variance_threshold option)? Or are there disadvantages in the latter method?
Thanks!
Sam