average montage

✉️ Mailing List Archive (read-only)
1

Dear all,

Is there a way to set up an averaged montage for the EEG channels that we record simultaneously with MEG (Elekta Vectorview)? We're thinking of averaging more than 20 channels and view it with mne_bowse_raw. The "Define derivations" can allow me to manipulate 5 channels at a time. I can define some addition of several of these 5-channel groups, then divide by the total channels used, but it's a bit cumbersome and I wonder if there're easier ways to do it.

Thanks.

Zhimin

2

Hi Zhimin,

This is actually the default in mne_browse_raw. To check it please check projections: usually the Average EEG Reference box is checked. Adjust -> Projections

or did you mean something else?

D

3

Thanks a lot, Dan.

Can you tell me exactly what channels are being averaged in this "Average EEG reference"? For example, I might have bad EEG channels in the recording. Are those still used in calculating the EEG average? Also, I made a bunch of derived EEG channels for my bipolar montage, etc. Are those derived channels used in calculating the EEG average as well?

Zhimin

4

Hi Zhimin,

5

Thank you very much, Matti.

I did try "mne_mark_bad_channels" for some bad EEG channels for a raw fif file created by MaxFilter, but later on when I use "mne_browse_raw" to view that file I could still see those bad EEG channels. That's why I am uncertain whether the default "Average EEG reference" I got from "Adjust -> projection" included those bad EEG channels into the average or not. If I define the derived channels manually then I can be sure only good channels are used. Now I feel more certain about how the default "Average EEG reference" works. Thanks a lot for clarifying things, :slight_smile:

Zhimin