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

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julienjulien
February 02, 2021 02:54PM
Hello AFNI group,

I am working with brain vascular reactivity data.
We use changes in CO2 as our stimulus file and acquire data using BOLD imaging.
We usually do a simple linear regression of BOLD by the end tidal CO2. We also have a script to convolve the the end tidal CO2 with an exponential of variable time characteristic to account for variable speed of vascular reactivity depending on location and diseases.
This works pretty well to account smoother BOLD responses in impaired vasculature ...

However, I would like to be able to recover the HRF using 3dDeconvolve with the BLOCK or TENT function , with something like:

3dDeconvolve -mask CVRmask+orig -input CVR_raw_scaled+orig -polort 1 -num_stimts 1 \
-stim_file 1 CO2.1D -stim_label 1 CO2effect \
-stim_maxlag 12 \
-stim_times 1 tname BLOCK(1,1) ...

The problem is that I cannot make a tname file because the CO2 is not only ON(1) or OFF(0) but rather a graded stimulus with values between 0 and 1 ...

Any suggestions/ help?

Thank you,

Julien
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Physiological stimulus

julienjulien February 02, 2021 02:54PM