My lab has a few questions about using the segmentation module in SPM12. We are doing task-based fMRI analyses. Our current pipeline includes: coregister the MPRAGE to the MNI 152 template, calculate VDM, realign and unwarp, coregister the mean functioning image (other images included in "other images") to the coregistered MPRAGE.
For segmentation, the default bias FWHM is 60mm cutoff. Is there any reason to change this? It looks like a previous post suggested to keep the default. https://www.jiscmail.ac.uk/cgi-bin/webadmin?A2=spm;1eeea036.0905
The default for "Warped tissue" for tissue types is "unmodulated". When is it appropriate to use modulated vs unmodulated? Is this primarily relevant for VBM and not for fMRI? If we have participants with atypical brain volumes (e.g., small cerebellum) should we do select "modulated"?
If we use 6 tissue types, is it best to use "Native + Dartel" for the first three tissue types and "none" for the remaining tissue types?
Thank you very much!