Dear AFNI experts,

I am analyzing some resting-state data. I also collected physiological recordings (cardiac and respiratory) for this dataset.

For preprocessing the dataset, I am following this order of blocks on afni_proc.py:

despike > ricor > tshift > align > tlrc > volreg > mask > regress

My ricor regressors are created from RetroTs.py - which outputs 13 columns of regressors. This includes RVT (respiratory volume per time), along with regressors for the phase of the cardiac and respiratory signals.

One of our collaborators suggested we should also include the cardiac rate (cardiac rate= 1/interval between the cardiac peaks) as a regressor to account for variations in cardiac rate during the scan duration. Importantly, RVT and cardiac rate should be convolved with the respiratory response function and cardiac response function, respectively.

My questions are:
1. When AFNI regresses out the RVT (derived from RetroTs.py), along with the other ricor regressors, does it convolve it with the respiratory response function before doing so?

2. How do I go about adding the cardiac rate convolved with the cardiac response function as a regressor into AFNI (before bandpass)?

Thank you,
Avi