[Eeglablist] Reference to linked mastoids - Neuroscan

[Makoto Miyakoshi]

Dear Tara,

Sorry for belated response.

> 2. I also tried entering the following from the command line:
> EEG = pop_reref (EEG, [21,22], 'keepref', 'on');

Why do you want to keep the earlobe data? It's better to discard it. They
do not have location either (especially if they were linked... just in case
you haven't heard of it, physically linked earlobe electrodes are bad,
avoid it.)

Makoto




On Wed, Mar 15, 2017 at 7:44 AM, Tara Davis <taradavis001 at gmail.com> wrote:

> Hi all,
>
> I usually use a 64 channel cap with averaged mastoids as my reference.
> Regrettably, I recently obtained pediatric 20 channel caps and learned
> afterwards that they have linked mastoids. I would return them for unlinked
> mastoids, but I've already lost a lot of time on this project.
>
> I've been unable to get EEGLAB to recognize the linked electrodes as the
> reference. M1 & M2 were not present in the channel locations.  I used the
> M1-M2 channel locations from my 64 channel file to append these channel
> locations in EEGLAB (added channels 21 & 22).  Then I tried to reference
> the mastoids in 2 ways:
>
> 1. From the GUI: I clicked on Re-reference data to channels, retain old
> reference channels in data and add current reference channel back to data.
> M1-M2 were available.  However, when I added them, I received an error
> message, "Aborting - you must enter one or more reference channels."
>
> 2. I also tried entering the following from the command line:
> EEG = pop_reref (EEG, [21,22], 'keepref', 'on');
>
>
> I have two questions.  (1) Is there anyway to troubleshoot this problem?
> (2) If I can't fix it, will it be a problem that the reference will be
> unknown for ICA, even though there was a reference when the data was
> recorded?
>
> Thanks,
> Tara Davis
>
>
>
> --
> Tara M. Davis, Ph.D. CCC-A
> University of South Alabama
> Associate Professor
> Department of Speech Pathology & Audiology
>
>
>
>
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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