Dear experts,
I used mri_concat to concatenate sig.mgh files from fixed-level analysis (combining runs within each subject). All input files when viewed as initial single frame images look correct. For one person, however, in the multiframe image the sig.mgh looks just like noise (see attached picture). I used only --i and --o in the mri_concat command line. What could have happened? I get no error messages and everything else looks ok.

Thank you for your help,
Aga