I have preprocessed a set of resting state functional images through fMRIprep version 20.2.6. For the denoising step, using AFNI’s 3dTproject, I would like to regress out the first five principal components generated from aCompCor, 6 head motion parameters and their derivatives, apply a simultaneous bandpass filter (0.01 - 0.08 Hz), and detrend. I saw on the fMRIprep outputs page that it is recommended to include the cosine regressors in the regression matrix when using Compcor components. If my understanding is correct, by including the cosine regressors, the data will be high pass filtered to retain frequencies above 0.008 Hz. I was wondering if it is appropriate to apply bandpass filtering when the cosine regressors are also included in the regression matrix (i.e., double filtering)? Put another way, how could I bandpass filter the data (e.g., 0.008 - 0.009 Hz) while including aCompCor and associated cosine components in the nuisance regression?
Thank you in advance!