Hi,

I am trying to run an analysis for an event related design and have a few issues related to 3dDeconvolve and the creation of my stim files.

Each event (picture viewing) lasts for 2.5 s and is separated by a 12.5s ITI. Each run begins with a 12.5 ITI. I have 3 separate runs (TR = 2.5s, 185 TRs per run). There are 3 different types of pictures (pleasant, unpleasant, and neutral) that are randomly presented throughout each run. I concatenated the runs prior to running 3dD, and am currently using the 1st 12.5s ITI from the 1st run as the 'rest' condition.

I initially used waver to create a stim file for each condition, but read on the message board that -stim_times was a better method to use? The results I get from using these different methods are different and I have no idea why. Using -waver, I created 1 stim file for each image category and ITI for the entire concatenated scan.


using -waver to create stim files
--------------------------

3dDeconvolve -input 17593_allScaled+orig \
-concat '1D: 0 185 370' \
-nfirst 0 \
-num_stimts 4 \
-stim_file 1 ITI_all.1D \
-stim_label 1 ITI\
-stim_file 2 17593_pleasant_all.1D \
-stim_label 2 pleasant\
-stim_file 3 17593_unpleasant_all.1D \
-stim_label 3 unpleasant\
-stim_file 4 17593_neutral_all.1D \
-stim_label 4 neutral\
-polort 4 \
-glt 1 P-N.txt -glt_label 1 P-N \
-glt 1 U-N.txt -glt_label 2 U-N \
-glt 1 U-P.txt -glt_label 3 U-P \
-tout -bucket 17593_glm1

--------------------------

using -stim_times

--------------------------
3dDeconvolve -input 17593_allScaled+orig \
-concat '1D: 0 185 370' \
-nfirst 0 \
-num_stimts 4 \
-stim_times 1 ITI.1D 'BLOCK(12.5)' \
-stim_times 2 17593_pleasant.1D GAM \
-stim_times 3 17593_unpleasant.1D GAM \
-stim_times 4 17593_neutral.1D GAM \
-polort 4 \
-glt 1 P-N.txt -glt_label 1 P-N \
-glt 1 U-N.txt -glt_label 2 U-N \
-glt 1 U-P.txt -glt_label 3 U-P \
-tout -bucket 17593_glm
--------------------------

I don't get any errors when running either method, but I do not know how to check whether either of these methods are accurate. Any help or suggestions would be greatly appreciated.

Many thanks,

-Steve