AFNI Message Board

Dear AFNI users-

We are very pleased to announce that the new AFNI Message Board framework is up! Please join us at:

https://discuss.afni.nimh.nih.gov

Existing user accounts have been migrated, so returning users can login by requesting a password reset. New users can create accounts, as well, through a standard account creation process. Please note that these setup emails might initially go to spam folders (esp. for NIH users!), so please check those locations in the beginning.

The current Message Board discussion threads have been migrated to the new framework. The current Message Board will remain visible, but read-only, for a little while.

Sincerely, AFNI HQ

History of AFNI updates  

|
October 29, 2017 02:27PM
Hey guys, I have a theoretical question.

I'm running 3dDeconvolve on simulated data to check out an experimental design. I've read the 3dDeconvolve manual but it's dated 2001 when stim_file was the norm. I had emailed Doug Ward some questions that he was awesome enough to answer and he recommended for my simulations, to use binary stimulus timing files and the stim_file option in 3dDeconvolve.

Long story short I did 3dDeconvolve on my data in 2 ways:
1) With the -stim_times options using a 'BLOCK(12,1)' duration for 12s stimuli.
2) With the -stim_file options using binary stimulus files (only 1 one where the onset was) and a -minlag option of 0 and -maxlag option of 12.

The -stim_times option gives almost perfect results, right on top of my simulated data but the -stim_file option looks vastly different. This isn't a huge problem because I'll just use -stim_times in my actual analysis but I'm curious as to why the results are so different. In both cases I am also inputting shock onsets (again as either stimulus_times or stim_files, respectively) and it looks like in the case of -stim_files the shock is also being modeled as part of the stimulus which makes it look messed up but I'm just not sure why -stim_times would take care of that but stim_file wouldn't. I mostly just want to know the difference between the two analyses. My two commands are below.

1) 3dDeconvolve -input1D simulated_all_cs_all_shock.1D -force_TR 2 -polort 0 -num_stimts 5 -stim_times 1 stim_test_times_one_ones.01.1D 'BLOCK(12,1)' -stim_times 2 stim_test_times_one_ones.02.1D 'BLOCK(12,1)' -stim_times 3 stim_test_times_one_ones.03.1D 'BLOCK(12,1)' -stim_times 4 shock_test_times.01.1D 'BLOCK(1,1)' -stim_times 5 shock_test_times.02.1D 'BLOCK(1,1)' -xout -iresp 1 CSp_sim_iresp_sts -iresp 2 CSm_sim_iresp_sts -iresp 3 CST_sim_iresp_sts -fitts sim_fitts_sts -errts sim_errts_sts

2) 3dDeconvolve -input1D simulated_all_cs_all_shock.1D -force_TR 2 -polort 0 -num_stimts 5 -stim_file 1 CS+_one_ones.1D -stim_file 2 CS-_one_ones.1D -stim_file 3 CST_one_ones.1D -stim_file 4 CS+_shock.1D -stim_file 5 CST_shock.1D -stim_minlag 1 0 -stim_maxlag 1 12 -stim_minlag 2 0 -stim_maxlag 2 12 -stim_minlag 3 0 -stim_maxlag 3 12 -stim_minlag 4 0 -stim_maxlag 4 1 -stim_minlag 5 0 -stim_maxlag 5 1 -xout -nfirst 0 -iresp 1 CSp_sim_iresp_sfile1 -iresp 2 CSm_sim_iresp_sfile1 -iresp 3 CSt_sim_iresp_sfile1

Thanks for any insight!

(P.S. I have also tried using -stim_files where there is a 1 not just at the onset but, but 6 1s in a row for each stimulus representing that it's on screen for 12s (6 TRs) and it looks even worse).
Subject Author Posted

Why do stim_times and stim_file give vastly different outputs?

lhopkins October 29, 2017 02:27PM

Re: Why do stim_times and stim_file give vastly different outputs?

rick reynolds November 01, 2017 04:27PM