Linear detrending

Linear detrending is a GLM option that allows you to remove linear drift from your data. It is applied separately to each time series from each run (4D file), so there may still be scan-to-scan mean signal differences. It basically fits a regression line to your data, and removes the slope, leaving the mean unchanged.

Linear detrending is like mean scaling in that it is not applied to your image data files, it is applied to your data internally just before regression.