[Eeglablist] Data Processing Steps for ICA?
Paul Yu-Chun Chang
Y.Chang at lipp.lmu.de
Wed Nov 5 00:29:29 PST 2014
Dear Arno & Makoto,
Many thanks for your reply and the suggested pages; they are indeed very
helpful. One small question I still have, then, is that it is suggested in
Makoto's page to discard (any) 1 channel from the data at the step of
average-rereferencing (due to reduction of data rank by 1), before running
ICA. If I just rereference after ICA, would ICA-matrix transformation also
take care of the data rank issue or should I still discard 1 channel?
Thank you very much,
2014-11-05 9:03 GMT+01:00 Arnaud Delorme <arno at ucsd.edu>:
> There is also this page just in case.
> Makoto, I have slightly edited your new page.
> > 2. When and how to perform re-referencing:
> It seems I should re-reference to average before ICA, but there seems to
> be some counterarguments, too:
> Just re-reference to the average reference. Don't forget to reject one
> channel after this.
> Yes, I would reference to average reference before running ICA as well
> although this is not critical (you can always rereference after running ICA
> and this will transform the ICA matrix as well). After running ICA for
> years, it seems that decomposition using the average reference are slightly
> better. However, there is no formal comparison I know of. In theory, since
> it is all linear, it will not change anything for ICA (although because of
> numerical implementation it might).
> > I'm not pretty sure whether to include EOG channels either, as there
> seems to be pros and cons:
> Do include EOG channels for ICA. I made a wrong answer last time.
> I would include the EOG channels if you recorded them with the same
> reference as ICA. Otherwise do not include them.
> Hope this helps,
> On Sat, Oct 25, 2014 at 2:54 AM, Paul Yu-Chun Chang <Y.Chang at lipp.lmu.de>
>> Dear All,
>> I have 32-channel Neuroscan recordings (ca. 1 hr per subject) and am
>> recently trying to use ICA to remove blinks and eye movements from the data
>> (EEGLAB version 126.96.36.199b). After checking out some relevant
>> discussions/wiki pages/tutorials I find myself however still a bit confused
>> (particularly regarding re-referencing, baseline correction, and channels
>> to be included when running ICA) and am having some further questions. I'd
>> really appreciate your help.
>> Some essential steps as I understand now involve (pls correct me if I'm
>> 1. Reject bad epochs/channels to prune the data.
>> (source: http://sccn.ucsd.edu/wiki/Chapter_09:_Decomposing_Data_Using_ICA
>> 2. Train ICA firstly on 1 Hz high-pass filtered pruned dataset.
>> 3. Apply ICA weights to the same subject's 0.1 Hz high-pass filtered data
>> and evaluate components.
>> (source: http://sccn.ucsd.edu/pipermail/eeglablist/2011/004424.html)
>> 4. Interpolate bad channels.
>> I'm however not so clear about:
>> 1. When to perform base-line correction:
>> It seems most people suggest not to do it before ICA training based on
>> Groppe's 'split-half' paper:
>> But there are some counterarguments:
>> So I guess it's still better to do it after ICA?
>> 2. When and how to perform re-referencing:
>> It seems I should re-reference to average before ICA, but there seems to
>> be some counterarguments, too:
>> I'm not pretty sure whether to include EOG channels either, as there
>> seems to be pros and cons:
>> Also is it all right to use average of M1/M2 (mastoid sites) for
>> re-referencing instead? Should M1/M2 be included for ICA training?
>> Many thanks!
>> Paul Yu-Chun Chang
>> Graduate School Language & Literature Munich - Class of Language
>> Ludwig-Maximilians-Universität München
>> Schellingstraße 10
>> 80799 München, Deutschland
>> Email: Y.Chang at lipp.lmu.de
>> Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
>> To unsubscribe, send an empty email to
>> eeglablist-unsubscribe at sccn.ucsd.edu
>> For digest mode, send an email with the subject "set digest mime" to
>> eeglablist-request at sccn.ucsd.edu
> Makoto Miyakoshi
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, University of California San Diego
> Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
> To unsubscribe, send an empty email to
> eeglablist-unsubscribe at sccn.ucsd.edu
> For digest mode, send an email with the subject "set digest mime" to
> eeglablist-request at sccn.ucsd.edu
Paul Yu-Chun Chang
Graduate School Language & Literature Munich - Class of Language
80799 München, Deutschland
Email: Y.Chang at lipp.lmu.de
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the eeglablist