About bad channel

[xiongruochu]

Hello,

I'm dealing with bad channels using Power Spectrum Density map.
I referred to your literature [MEG/EEG Group Analysis With Brainstorm], and some other discussion topics, but I'm still confused with this rather subjective preprocessing step.

The figure below shows typical PSD maps of my recordings. The channel marked in red (RC24 and ZP05) are floating above and below other channels. My frequency of interest is 80-90 Hz, so can I just mark them as bad channels? (I think the situation is similar to what you presented in your literature [MEG/EEG Group Analysis With Brainstorm])

AND another question is,
if I mark a channel A as bad in one participant, do I need to mark this channel A in all other participants for all runs?

Best wishes

[Sylvain]

Yes, I would mark these two channels as bad. Depending on the data derivatives you are planning to extract from the group, you may need to exclude these channels from all other individual recordings as well.
Finally, there are multiple noisy peaks in your data ~5, 15, 20, 30 etc. which look like harmonics of a major signal contaminant. Please double check whay may be the cause and in any case, you may need to apply appropriate notch filters (including in the 80-90Hz band of your interest).

[xiongruochu]

Got it! Thanks a lot!