I performed subject-level analysis in AFNI for a specific task-based scan, which included standard steps in afni_proc.py such as motion correction, detrending, etc. In step, I also obtained t-statistics for event stimuli. Suppose the t-statistic spatial maps for a stimulus are in a subbrick labeled "stim1" in the stats/REML output file. I wanted to combined the "stim1" subbrick for each subject in the sample into a single volume named "sample.nii" that I plan to use as input into the Broccoli permutation testing software for group analysis. What is the best function for doing so that will guarantee the order of volumes is preserved? Thank you.