you would add them as task regressors and set up first level contrasts as you describe. I'm not sure of your last question (ie, second-level comparison of their effect). Do you want to compare, eg, respiration vs motion? I'm not sure how you would do that.

On 2/6/2023 5:18 AM, Marilena Wilding wrote:

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Hi Freesurfers!

I would like to compare the effect of different nuisance regressors (I.e., cardiac and respiratory signal, motion) on my resting-state data. For that I’m adding the respective regressors to my first-level GLM. Now, how can I best compute a contrast between the effect of different physiological regressors and motion? Would I add them as task regressors in 1st level or rather as nuisance regressors and how can I get second-level comparison of their effect?

Thanks in advance for your help!

Best,

Maria

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