Dear Freesurfer experts,

I've run a longitudinal two stage model of 2 time points to look at the rate of change in surface area and whether my two groups change differently. I find a superior parietal cluster in the right hemisphere. So far I've already run the mri_glmfit-sim to get the values of rate of change in this cluster for each subject. Now I would like to extract the peak vertex that I get the coordinates of from mri_glmfit-sim for each subject from each time point.

I have tried to use mri_convert

mris_convert -c $SUBJECTS_DIR/WL8K_1.long.WL8K.base/surf/lh.thickness.fwhm10.81kids_template.mgh $SUBJECTS_DIR/001/WL8K_1.long.WL8K.base/lh.orig $SUBJECTS_DIR/WL8K_1.long.WL8K.base/lh.thickness.fwhm10.81kids_template.vertices.asc

however, I get this error message:

ERROR: number of vertices in /nobackup/etsch2/kids/prepost-61kids/WL8K_1.long.WL8K.base/surf/lh.thickness.fwhm10.81kids_template.mgh does not match surface (97361,109356)

I've read in other threads that I'm supposed to use mri_surf2surf to map it to my template (81kids_template). I thought I had already done that before the analysis when running long_mris_slopes --qdec ./qdec/long.qdec.table.dat --meas thickness --hemi lh --do-avg --do-rate --do-pc1 --do-spc --do-stack --do-label --time years --qcache 81kids_template

Could you tell me what I need to do to extract the values of the peak vertex in my significant cluster for each subject and each time point? Thank you so much! Clara