Physiological stimulus

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,