Doug:
Thanks for your quick reply -- but I still have some big holes in understanding, probably because I'm having a hard time digesting the mri_aparc2aseg's wiki page.
For the ribbon-related parameters we seem to have the 3 choices:
no ribbon param ... or ... --ribbon ...or... --noribbon
The Description presumably applies to using no ribbon parameter, and describes that *both* aseg *and* the surface-derived ?h.ribbon are used. If that's the case, then what does the --ribbon arg add?
It goes on to say "This can be turned off with --noribbon". What can be turned off? Use of ?h.ribbon? Or relabeling of the "unknown" voxels to zero (ie: aparc+aseg would have them labeled as "cortex").
Finally, for my task where I hope to ignore aseg entirely, is my solution to fake up an aseg volume filled with "cortex" voxels, and use that for input? (And I'm not seeing an argument to tell mri_aparc2aseg to use a different aseg...).
Thanks,
Graham