[Freesurfer] For multiple comparisons

Hi there, First, I ran "mri_glmfit" using a mask (subcortical regions) as follows: mri_glmfit --glmdir g1v1.wls --y ces.nii.gz --wis cesvar.nii.gz --fsgd g1v1.fsgd --C age.mtx --mask brain.mni305.2mm.nii.gz --fwhm 5.

Second, I'm going to process "mri_glmfit-sim" to perform a cluster-wise correction for multiple comparisons. Which I select the comment? 1) mri_glmfit-sim -glmdir g1v1.wis -3spaces -grf 2 abs 2) mri_glmfit-sim -glmdir g1v1.wis -perm 1000 2.0 abs -cwp 0.05 -3spaces -bg 16 Especially, I use the mask the subcortical regions, not cortical regions. Should I remove “-3spaces” in the commend or what do I do instead of “-3spaces”?

Thank you, Gwang-Won