[Eeglablist] channel merging warning

[Tarik S Bel-Bahar]

Hello Gregory, brief notes below. Best wishes.


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This is an unlikely/unusual error with eeglab. I've used study a lot with
128 and 256 channel data, and it does not seem to have problems with
channels when the same channel file is correctly loaded when importing the
eeg into eeglab, regardless of whether the files in question have different
channels dropped.

I would recommend you look closely at the steps involved with
a. loading correct channel file manually (try it via gui first and confirm
no errors via channel visualization tools) -
b. saving .set file after channel removal
c. any steps where you might be applying new/different labels to the
channels

If you haven't had a chance to as of yet, I recommend trying eeglab
tutorial, eeglab tutorial data, reviewing eeglab wiki and eeglablist,
reviewing eegh output to make sure any scripts are correct, and reviewing
past similar posts on your topic.

As a last alternative, before running study, you may want to loop through
your files and interpolate the channels so that all files have the same
channels, and the same channel information in the EEG structure.

Last, note that it is totally possible to do manual/visual selection of bad
channels with 256 channel data, it should not take more than 10 minutes per
file/session. One needs to review which channels are dropped, and whether
major clusters of channels are being taken out. Further, note that with
high-density montages some reasearch groups regularly drop/discount the
lowest channels on the head and the channels on the face, which often tend
to be most contaminated with muscle noise and/or bad signal.

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On Thu, Jun 15, 2017 at 3:53 AM, Grégory SIMON <simon at cyceron.fr> wrote:

> Dear all,
>
>
>
> After artifact corrections our different datasets haven’t the same number
> of electrodes.
>
> In the study panel, when we select “Precompute channel mesure” using
>  “spherical interpolation of missing channels” we obtain sometime an error
> because of dissimilar files in the structures and we have the messagebox
> “error in function legendre at line 106”
>
> An idea? Because we have 256 EEG channels, exclusion of electrodes by
> visual inspection is not possible.
>
>
>
> Best regards
>
>
>
> Gregory SIMON
>
>
>
>
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