Thanks, Bob! It's good to know that the oder of temporal filtering and spatial smoothing doesn't matter. Also thanks a lot for introducing "InstaCorr" to me.

When I ran temporal filtering, I use the option -retrend to restore the mean and linear trend. The command looks like the following:

3dFourier -prefix h3938_rest_reg_bp -lowpass 0.1 -highpass 0.01 -retrend h3938_rest_reg+orig.

So in this case, is it okay to normalize the time series to have mean 100? If not, at which step should I do this? My current preprocessing stream is:

1. to3d to read in images
2. align_epi_anat.py to align mprage to fMRI data set
3. Despike
4. Slice-timing correction
5. Normalize the brain to a template
6. Motion correction
7. temporal filtering(Band pass filtering 0.01-0.1Hz)
8. spatial filter (smoothing)
9. Normalization the voxel time series to have mean 100

Thanks a lot!

Wenzhu