Hi Rick.

Thank you for your reply. I apologize for the misleading file names. The input file has NOT had the average and drift removed already. It has been motion corrected and a small spatial filter applied. There is no doubt that these datasets are a bit funky...I am trying to figure out why and if there are any salvageable data. What it looks like to me is that there is the scanning area outside the actual brain that has a higher signal than what is inside. So, when I try to use 3dClipLevel or 3dAutomask, it leaves me with this spherical outline, and no actual brain activation. That is why I wanted to try to clip above, rather than below the value determined by 3dClipLevel, to see if I could reverse the results.