Dear FS Experts,I want to measure the thickness difference between two groups, control and experimental group. And every subject scaned twice.I look at the page: http://surfer.nmr.mgh.harvard.edu/fswiki/LongitudinalProcessingand some reply in Mail-list.I looked one method: Subtract time2 to time1 manually and do a regular GLM.How to substract times? Maybe the results after the cmd are? "recon-all -base con* -tp con*_MR1 -tp con*_MR2 -all recon-all -base sub* -tp sub*_MR1 -tp sub*_MR2 -all" Can I do GLM between con* and sub* directly?Could you please tell me how to do? Many thanks!Best regards,Melody