Excessive head motion in CAM-CAN resting state fMRI, more than 50% had mean FD>0.2

i’ve preprocessed the CAM-CAN rsfMRI data using fmriprep. Looking at the head motion statistics, if we go by any conventional exclusion criteria (e.g., FD> 0.2 , RMSD, >0.25 or subjects with more than 20% of the volumes with RMSE >.25), i will have to exclude at least 20% of the data! if we go by the FD>0.2, it will be more 50%. Not sure if i’ve done anything wrong, fmriprep completed without any errors.

i wonder if anyone working with the CAM-CAN rsfMRI dataset encounter this as well?

i’ve seen a couple of published CAM-CAN studies, most only excluded a handful using very vague criteria (i.e. having FD 2 SDs above mean), or did not mention any exclusions of subjects due to head motion at all.

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