[Eeglablist] Extra components in clean compared to uncleaned EEGs-reliable or not?

[Tzeng, Tony H.]

Hi all,

I ran the ICA on unclean vs cleaned data for one subject at rest, and I found two extra components in the cleaned data (which appear to be neural sources based on characteristics, scalp map/ERPimage, etc, and they were also identified as "Brain" with the new ICLabel plugin). What would be the best explanation for them to not have shown up at all following ICA of the raw data? Would it be that they were, somehow, masked in the several noisy epochs that were rejected in the cleaned version? Or would it be that these new components are actually artifactual in nature as well?

Are there any suggestions for how to confirm/test the reliability of these "new" components? Is this occurrence usual when comparing clean to uncleaned EEG data? I was expecting both to have similar number of components since they are from the same subject (and almost identical, +/- some noisy epochs). Thanks for all of your patience.

Best,
Tony