[Freesurfer] LME Mass Univariate analysis and .long directories

FS experts,

I have two questions, when running mris_preproc and mri_surf2surf should I be passing these any of the .long directories created with recon-all -long? As I read through the tutorial I’m missing their significance in the analysis section of the longitudinal stream. It seems like fsaverage is being used (I’m not sure when that was even generated)

Secondly, I see that mris_preproc outputs a thickness.mgh file, but I’m wondering where, in your tutorial examples lh.thickness_sm10.mgh comes from/is located. Found in

mri_surf2surf --hemi lh --s fsaverage --sval lh.thickness.mgh --tval lh.thickness_sm10.mgh --fwhm-trg 10 --cortex —noreshape

best,

jon