[Eeglablist] baseline correction

[Alday, Phillip]

Hi Barbara,

Taking a baseline far away from your epoch of interest defeats the point of baseline correction.

That said, I don't think traditional baseline correction is really a good approach in most cases, see e.g. my preprint here: https://arxiv.org/abs/1707.08152

Instead, you should use your baseline window as a predictor in a regression model. In EEGLAB, I think you could achieve this with clever use of the LIMO plugin, but I'm not 100% sure. I tend to only do basic signal processing in EEGLAB before moving things over to multilevel regression models in R.

If you do this right, your baseline predictor can interact with condition, etc., which means you can also avoid many (most?) of the difficulties with the "no systematic differences in electrophysiological activity in the baseline window" assumption.  Or is there some other reason why you can't use pre- or post-stim time?

Beyond regressing out your baseline, there are two other options:
1. Use your whole epoch as a baseline (mean centering / DC-offset within epochs)
2. Use a stronger high-pass filter (but be careful, see various publications and the debate Widmann & Maes  vs. Tanner debate in the Journal of Neuroscience Methods).

Each of these has different advantages and disadvantages.

Best,
Phillip


From: Barbara Morera <Barbara.Morera at nottingham.ac.uk<mailto:Barbara.Morera at nottingham.ac.uk>>
Date: 14 August 2018 at 17:19:37 GMT+2
To: "eeglablist at sccn.ucsd.edu<mailto:eeglablist at sccn.ucsd.edu>" <eeglablist at sccn.ucsd.edu<mailto:eeglablist at sccn.ucsd.edu>>
Subject: [Eeglablist] baseline correction


Hi everyone,


I need to remove the baseline from my data but I can't use pre-stim or post-stim time.


I have a 1 minute dataset of a resting period from the participants that I could use to remove the baseline from the data.


However, I don't know how to actually do this, since there are only two functions (that I know) to remove baseline: pop_rmbase and rmbase, but they don't seem to be useful for what I want to do.


Many thanks in advance for any help,

Barbara

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