Hello Freesurfers,

I am working on a PET surface based analysis between two groups. I did the following:

1. I concatentaed the PET images using the command "mris_preproce" and I got the file (lh.mgh) for left hemisphere and (rh.mgh) for right hemisphere.

2. I smoothed "lh.mgh and rh.mgh) using the command:

mri_surf2surf --s fsaverage --hemi lh --fwhm 10 --sval lh.mgh --tval lh_sm10.mgh

3. I studdied the diffence between the groups usiing the command:

mri_glmfit --y lh_sm10.mgh --fsgd fsgd.dat --C contrast.mtx --surf fsaverage lh --cortex --glmdir lh

4. I corrected the results for multiple comparison using the command:

mri_glmfit-sim --glmdir lh --cache 30 pos --cwp 0.01 --2spaces

I want to narrow (reduce the strictness) of the correction for multiple comparision to a specific label (e.g. precentral gyrus). I changed the commands "mri_glmfit" and "mri_glmfit-sim" as follow:

mri_glmfit --y lh_sm10.mgh --fsgd fsgd.dat --C contrast.mtx --surf fsaverage lh --label precentral --glmdir lh

mri_glmfit-sim --glmdir lh --cache 30 pos --cache-label precentral --cwp 0.01 --2spaces

I got error that the label "precentral" is not exist. I was unable to find this label in the folder "fsaverage". Kindly:

1. whct I am doing wrong?

2. How can I create this label ? and in whcih folder it must be placed?

Best,
John