Hi all,
I'm doing some analyses on EEG data acquired with a 256 EGI hydrocel cap.
While preprocessing I came across these rythmic and focal artifacts :
Colleagues of mine believe these are impedance artifacts due to a lack of contact between the scalp and EEG electrodes at that location.
Regardless of there origin, do you believe these can be cleaned ? If so, how could I proceed using brainstorm ? I tried the "detect other artifacts" option which identified some of the bad segments but not all of them. These artifacts are crucial to remove because the following analyses include phase-based functional connectivity, thus they are likely to result in spurious connectivity.
I recommend you run an SSP analysis over the entire recording. The artifact is so strong and stereotypical that it should be absorbed by the first SSP component, and should be considerably attenuated once you project the data away from it.
Hi Sylvain thanks for the answer,
I tried SSP on the whole signal but the artifact remains in the signal.
Here is the signal and SSP topographies and component time-series befor and after removing the first comp:
Before:
