Adding physiological regressors to fmri confounds file

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Hello experts,

This is a general question about denoising with a specific follow-up. We are currently working with task-fMRI but I am also curious about how this issue applies to resting state.

I have seen users on this forum recommend against using physiological (heart rate/breathing) signals to generate regressors (e.g. with RETROICOR or physIO), since the 2007 Behzadi et al. paper found that these are largely accounted for by aCompCor. However, a recent 2023 publication by Krentz et al. suggests that RETROICOR can still account for significant signal variability, especially in certain individuals. I am wondering if it is still recommended to stick with aCompCor for the moment, or whether I should try and integrate our physiological recordings and somehow add them to the confound regressors file generated by fmriprep to use them in a later GLM.

IF adding these physiological regressors is now recommended, has anyone done this and could they let me know of any pitfalls to look out for? We have Siemens .phys and .puls files.

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Hi there,

I’m following up to see if there have been any updates on this topic. Have you started using physio regressors in your denoising pipeline, and if so, how has it worked out? I’d love to hear any recommendations you might have. Thank you!

Mary

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Hi @MaryW, we ended up skipping this step in the end, and are just using aCompCor. Part of the decision was based on efficiency in setting up the pipeline, and part was a fear of adding too many/too similar regressors and causing issues further down the road. But I would still love to hear advice from anyone who has done this!