afni.nimh.nih.gov

Hi I'm starting to write a script to process fMRI data. I would like to use participant's reaction time as the duration of each event. I'm coming from FSL word where I would set up a 3-column text file with onset duration and weight and so would set up the duration as the RT. I can't find how to do the same with AFNI, could you help me figuring that out?