Never mind, found the answer online, sorry about that!

On Mon, Dec 11, 2017 at 2:13 PM, Taylor, Johnmark <johnmarktaylor@g.harvard.edu> wrote:
Hello,

When using preproc-sess and selxavg3-sess, how is global mean scaling handled? Is the session-wide (4D) mean subtracted, is each volume's mean subtracted, or neither?

Thank you very much,

JohnMark