Mutiple stim functions in 3dDeconvolve program

AFNI Message Board
1

Hello AFNI experts,

I have 60s stimulation duration in a scan session. I plan to use two 30s block stim function (early stim func= BLOCK(30,1), late stim func= BLOCK(30,1)) option for the total 60s stimulation.

My question is for the early stim function BLOCK(30,1), does that consider the later 30s of stimulation as OFF (which is basically stimulation ON) and the same way for the later BLOCK function, does it consider the early 30s of stimulation as OFF?

#code:
3dDeconvolve
-input $input
-censor $censor
-polort A
-num_stimts 8
-stim_times 1 $stim_fileA ‘BLOCK(30,1)’ -stim_label 1 HEAT_Early
-stim_times 2 $stim_fileB ‘BLOCK(30,1)’ -stim_label 2 HEAT_Late
-stim_file 3 ${motion}‘[0]’ -stim_base 3 -stim_label 3 roll
-stim_file 4 ${motion}‘[1]’ -stim_base 4 -stim_label 4 pitch
-stim_file 5 ${motion}‘[2]’ -stim_base 5 -stim_label 5 yaw
-stim_file 6 ${motion}‘[3]’ -stim_base 6 -stim_label 6 dS
-stim_file 7 ${motion}‘[4]’ -stim_base 7 -stim_label 7 dL
-stim_file 8 ${motion}‘[5]’ -stim_base 8 -stim_label 8 dP
-tout -fout -rout
-x1D ${prefix}.xmat.1D
-x1D_uncensored ${prefix}.nocensor.xmat.1D
-xjpeg ${prefix}_xmat.jpg
-fitts ${prefix}_fitts.nii.gz
-errts ${prefix}_errts.nii.gz
-bucket ${prefix}_stats_epispace.nii.gz

2

Yes, it does. Assuming the HEAT_Late timing is 30s later than that of the Early, each would consider the other’s time as off.

Note that BLOCK is a 15s response curve though. So the ends of the Early responses will overlap with the starts of the Late responses. Hopefully there are reasonably long gaps between Late events and the next Early ones. But you will see that overlap in the X-matrix. Note that the Early regressor plus the Late regressor should sum to what a 60s BLOCK response would look like.

  • rick
3

Hi Reynold,

Thanks for replying. There is 30s difference between early and late stimulation onset. And there is 60s gap in between end of late to next early stim.

i.e.= the stim_early_file= 20 140 260 380 500 (s)
stim_late_file= 50 170 290 410 530 (s)

I just ran the data considering a whole 60s block BLOCK(60,1).
The sum of early regressor coefficients (beta) and late regressor coefficients did not come as same as 60s BLOCK regressor coefficients. Not sure what I might be missing.
edit: just found out that you meant regressor not regressor coefficients. Let me check that and come back

4

Hey Reynold,

I have checked the summed the early and late regressor and that matches with the whole 60s block regressor! Thank you so much for your help!

Best,
Adury

5

That’s great, Adury!

Thanks for the follup-up.

  • rick