About include or not A1 and A2 References

Hi!
I have a theoretical question about the EEG reference:

Some EEG records include reference channels like A1, A2, etc, I noticed that when EEG analysis include these channels it brings a little difference specially in bitemporal regions,

With A1 and A2 channels:

withA12

Without A1 and A2 (marked as bad channels):

withoutA12

Since it is assumed that reference channels must be innactive (or nearly) I don't know if is a better approach to mark that channels as bad, or if to include it

I would also like to know if to include A1 and A2 channels could affect or distort the source analysis results

Thanks in adavances!

:D!

The best reference to use for your EEG analysis depends on your hypotheses and your reference methods. We have limited experience with EEG, so this is a question to be asked to EEG experts. The literature about EEG referencing is rich, you should start with this.

I would also like to know if to include A1 and A2 channels could affect or distort the source analysis results

For source analysis, the recordings are always converted to an average reference. The output of the average reference will be different on the number of electrodes you include in your dataset.

The higher the coverage of the head the better, so my guess is that it's better to keep everything.

@Sylvain @John_Mosher?

1 Like

Thanks for the reply! :slight_smile: