Dear freesurfers,

I am trying to see what are the group differences in cortical thickness of patients with right and left FLE compared to controls using the GLM.
I created a txt file in gedit called my_age_fsgd.txt (please see the attachment) containing my subjects (patients and controls) and their age. I am not interested in doing a study versus gender just versus age.

Following the instructions from the tutorial I was running the mri_preproc:

mris_preproc --fsgd my_age_fsgd.txt \
  --target fsaverage \
  --hemi lh \                        
  --meas thickness \
  --out lh.gender_age.thickness.mgh
 

but I got an error: ERROR: no subjects specified. Also, what should be my contrast vector if I am not interested in considering the gender. I found in one tutorial that I should create age.mat if it does not exist and it should contain this line:
                                    
0 0 1

Why this numbers?

Can anyone give a hint please in how to eliminate my error and how to create the contrast vector in order to take in consideration only my subject's age?

Many thanks,
Antonella