hi, expert,

By mapping a surface label to a functional template, I want to extract the corresponding cortical gray matter region in the functional space. I know I should use the mri_label2vol command. 

In the help page of mri_label2vol, I see some examples of this command.

2. Convert a surface label into a binary mask in the functional space.
Fill in all the cortical gray matter. Require that a functional voxel
be filled at least 30% by the label:

mri_label2vol 
  --label lh-avg_central_sulcus.label 
  --temp f.nii 
  --reg register.dat 
  --fillthresh .3 
  --proj frac 0 1 .1 
  --subject bert --hemi lh
  --o cent-lh.nii

3. Convert a surface label into a binary mask in the functional space.
Sample a 1mm ribbon 2mm below the gray/white surface. Do not require a 
fill threshold:

mri_label2vol 
  --label lh-avg_central_sulcus.label 
  --temp f.nii 
  --reg register.dat 
  --proj abs -3 -2 .1 
  --subject bert --hemi lh
  --o cent-lh.nii

I want to extract the cortical gray matter on the functional images corresponding to the surface label. I do not know which of the above commands could obtain the result I want and which parameters I should use to obtain what I want.

For example 3, I do not quite catch what "Sample a 1mm ribbon 2mm below the gray/white surface. " this sentence means. 

Thanks for your help!


Best

Yuanchao