Hi rick,

Thanks again for your help. I still have two questions for you, which may seem silly.

First, you mentioned that " Using 'basic' and 'demean' should lead to the exact same results, except for the polort 0 terms ".

1) In the proc file generated by proc.py, I don't know whether the ' polort 0 ' you mentioned is in " running the regression analysis " (polort default value is 1) or in " using 3dTproject to project out regression matrix " (polort default value is 2). In my proc file , polort value is 2 in " running the regression analysis " , but polort value is 0 in " using 3dTproject to project out regression matrix ".

2) Using 'basic' and 'demean deriv', I got different results in the same subject. TSNR average is 260.187 in ' basic ' , TSNR average is 267.431 in ' demean deriv '. And the voxel by voxel correlation results between 2 runs are also different in basic and demean deriv.

This is my script.
(1) " -regress_apply_mot_types basic " in afni_proc.py
#!/bin/tcsh
###nocensor basic blur6
afni_proc.py -subj_id sub6.no.basic.blur6 \
-dsets s6.1+orig.HEAD s6.4+orig.HEAD \
-blocks despike tshift align tlrc volreg blur mask scale regress \
-copy_anat anat+orig \
-align_opts_aea -deoblique on -cost lpc+ZZ \
-tlrc_base TT_N27+tlrc \
-volreg_align_to MIN_OUTLIER \
-volreg_align_e2a \
-volreg_tlrc_warp \
-blur_size 6.0 \
-regress_apply_mot_types basic \
-regress_est_blur_epits \
-regress_est_blur_errts \
-execute
The proc file in attach file 'nocensor.basic'.
(2) " -regress_apply_mot_types demean deriv " in afni_proc.py
#!/bin/tcsh
###nocensor demean deriv blur6
afni_proc.py -subj_id sub6.no.demean.blur6 \
-dsets s6.1+orig.HEAD s6.4+orig.HEAD \
-blocks despike tshift align tlrc volreg blur mask scale regress \
-copy_anat anat+orig \
-align_opts_aea -deoblique on -cost lpc+ZZ \
-tlrc_base TT_N27+tlrc \
-volreg_align_to MIN_OUTLIER \
-volreg_align_e2a \
-volreg_tlrc_warp \
-blur_size 6.0 \
-regress_apply_mot_types demean deriv \
-regress_est_blur_epits \
-regress_est_blur_errts \
-execute
The proc file in attach file 'nocensor.demean'.

Second,I don't understand the meaning of " The 'deriv' case also regresses the 6 first differences, so those results will differ. ".Could you explain it in more detail?

Thanks a lot,
Dan