help > RE: scrubbing: removal and/or regression?
Apr 5, 2023  07:04 PM | Alfonso Nieto-Castanon - Boston University
RE: scrubbing: removal and/or regression?
Hi Amy,

The identification of potential invalid scans is performed during preprocessing (ART step). After that, scrubbing (where the effect of these potential outlier scans is removed from the BOLD signal) is performed during denoising, and it is implemented by introducing a separate regressor for each individual identified outlier scan in the "regression" stage of denoising. You may find more details about this process in:
https://www.nitrc.org/forum/message.php?msg_id=13100
https://web.conn-toolbox.org/fmri-methods/denoising-pipeline

Best
Alfonso
Originally posted by Amy Roy:
I feel a bit silly asking this question but i want to make sure I am clear what CONN is doing regarding scrubbing volumes. My understanding is that it removes volumes that exceed a motion and/or BOLD signal threshold. Does CONN also enter the number of scrubbed volumes as a first-level regressor at the denoising step? So, volumes are both removed and then there is a regressor? I have also been regressing out ValidScans at the second-level to control for any group differences. If someone could clarify what is happening at the preprocessing and denoising steps, I would appreciate it.
Thanks
Amy

Threaded View

TitleAuthorDate
Amy Roy Apr 3, 2023
RE: scrubbing: removal and/or regression?
Alfonso Nieto-Castanon Apr 5, 2023