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Dear FS experts,
I have a group of healthy subjects. Given a new individual subject, I want to compare its cortical thickness to the healthy group so that I can find where the thickness is abnormal (thickening or thinning).
I use fsaverage as the template subject to calculate mean and std of the healthy group. Since subjects in the healthy group have different ages, I do a "normalization" process to all the subjects in the group BEFORE calculating the mean and std. Thus the normalized healthy group can be regarded as all subjects having the same "standard" age. The normalization process is just multiplying some pre-obtained scale (varied by age, but not linearly ) to the file ?h.thickness.fwhm0.fsaverage.mgh of each subject that are already calculated by "recon-all --qcache" command. So the mean and std of the group are actually weighted in the sense of Freesurfer's recon-all results.
My questions are:
1) If I do vertex-wise t-tests by simply comparing individual subject's thickness to the group using mris_calc but WITHOUT using mri_glmfit, can I still use mri_glmfit-sim to do multiple comparisons correction? If yes, how?
2) If the answer is no for the above question, how should I use mris_glmft to implement my above thoughts so that I can use use mri_glmfit-sim? Specifically, how can I use the weighted mean for the group?
3) Take a step back, if I consider the weight is linearly correlated with the age, how to design the fsdg and contrast file?
Thank you very much!
Xiao