[Eeglablist] EOG channels included in ICA and DIPFIT

[Tim Curran]

A tangential question…

Makoto says, " I tend to include them [EOG channels]. If you exclude them, you typically find no frontal ICs”. There seems to be a common understanding that using ICA to correct for eye movements is OK if you are primarily interested in posterior EEG, but that ICA eye movement correction is problematic when interested in frontal EEG because ICA cannot clearly separate frontal activity from eye activity.  This logically follows from Makoto’s comment, but does anybody know of actual references, which demonstrate that ICA eye movement correction is OK if interested in posterior EEG, but not OK if interested in frontal EEG?
thanks
Tim



On May 10, 2017, at 10:22 AM, Arnaud Delorme <arno at ucsd.edu<mailto:arno at ucsd.edu>> wrote:

Dear Alessio,

Yes, include the EOG channels but as long as they have the same reference as the scalp channels. Otherwise, do not include them.
Best wishes,

Arno

On May 10, 2017, at 7:33 AM, Makoto Miyakoshi <mmiyakoshi at ucsd.edu<mailto:mmiyakoshi at ucsd.edu>> wrote:

Dear Alessio,

Getting back to you after 3 month!

> how to deal with ICs where EOG contributes for example for 20%, or 40%, or 60%?

This is a good question.
Usually EOG is decomposed well, so the result is rather black and white. You can reduce it by optimizing settings (using proper preprocessing and parameters.)

However, sometimes this mixture of brain EEG and non-brain artifact happens. In this case, you are forced to choose either false positive (include them) or false negative (exclude them). I tend to include them. If you exclude them, you typically find no frontal ICs.

Makoto




On Sun, Feb 12, 2017 at 1:31 AM, Alessio Matiz <muec at inbox.com<mailto:muec at inbox.com>> wrote:
Very dear EEGLAB-list,

is it correct to fit dipoles (via DIPFIT2-plugin) to ICs that have been found including EOG channel in the ICA decomposition (as Arno suggested in https://sccn.ucsd.edu/pipermail/eeglablist/2007/001801.html)?

From my datasets I removed ICs where EOG channel contributes for >90% of IC power (considering them artifactual ICs), but how to deal with ICs where EOG contributes for example for 20%, or 40%, or 60%?

Thanks,
Alessio



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--
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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