AM2 stimulus regressors

AFNI Message Board
1

Hello AFNI team!

I have been trying to implement an amplitude-modulated GLM to account for response times in the model. For about half my subjects, everything seems to be running fine. But for the other half, a seemingly random selection of amplitude-modulated stimulus-regressors come out as all NANs (in the attached image, the red line is an example of this). Any ideas why the amplitude modulation would fail?

Thanks!

  • Tom

stim_regressors.png
stim_regressors.png766×660 27.1 KB

2

Never mind, I figured it out! When creating my stimulus timing files, I forgot to remove trials where the subjects didn’t respond. These trials had “nan” as the response time, which explains why 3dDeconvolve could not scale the regressor.

3

Hi Tom,

For that first condition’s timing file (the xmat regressors are from the bottom up), what is the output of:

timing_tool.py -multi_timing stimuli/TIMING.txt -multi_timing_to_event_list GE:ALL -

That should show the modulators being applied. If the input were stimuli/*.txt, then it would show all of them (though then we wouldn’t know which is the problematic one).

  • rick
4

Great! Sorry for my late reply, though you might still be interested.

  • rick
5

Thank you very much! I actually didn’t know about timing_tool.py and it looks like it will be useful to me in the future!

  • Tom