[Eeglablist] Difficulties with Channel Locations

[Makoto Miyakoshi]

Dear Jessica,

> Is there a way to make the number of channels match so that channel
locations can be read while still keeping the extra face electrodes?

Yes I sometimes trick EEGLAB to make it accept extra channels into
EEG.data. You need a very basic Matlab coding skill to do it.

> If not would taking out these electrodes effect the efficiency of ICA?

Certainly. However, decomposing muscles using ICA is different from
decomposing EEG. It is most likely because the activation source of muscle
does not necessarily stays in the same spatial position. So I can't
guarantee that if you include muscle channels you can remove EMG from the
data... Scott is more optimistic about it.

> Do I need to digitize the face electrodes so that they also have a
location to do ICA effectively?

If that works yes why don't you do that? However, if you already have
datasets it does not help.

Makoto

On Tue, Mar 17, 2015 at 2:28 PM, Jessica Satterwhite <jessksat at nmsu.edu>
wrote:

>  Hello,
>
>
>  I am having trouble reading the channel locations in EEG data. The bdf
> data file I am trying to analyze has a total of 137 channels including 8
> face electrodes and a GSR sensor. The .elp file of the same subject which
> contains the digitized head model has a total of 128 channels as we did not
> digitize the face electrodes or GSR. When trying to read the channel
> locations from the .elp file, an error returns stating that the channel
> locations were not saved because the number of channels in the .bdf data
> file does not match the number of channels in the .elp file. We really
> would like to add the face electrodes in ICA so that noise from facial
> muscle movements can be removed from the data. Is there a way to make the
> number of channels match so that channel locations can be read while still
> keeping the extra face electrodes? If not would taking out these electrodes
> effect the efficiency of ICA? Do I need to digitize the face electrodes so
> that they also have a location to do ICA effectively?
>
>
>  Any help anyone could give me would be greatly appreciated.
>
>
>  Thank you,
>
>
>  Jessica Satterwhite
>
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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