[Eeglablist] eeglablist

[Tarik S Bel-Bahar]

Hello, some quick thoughts below. Thanks for letting the list know of your
eventual resolution so that other users can benefit from your experiences.

*********************************
*For issues with importing channels, check that you are using the correct
importer function by testing importing with the various importing functions
in eeglab, and examining the data/channels after import to see if any of
them work correctly.

*to be 100% sure that you have your channel locations correct (which is
critical for further processing and ICA), just try to make sure all the
channels are imported from the original file, and then Edit>Channel
Locations, and import the correct/full channel file list from your cap
vendor (build one if you need to from scratch, and/or append one with your
extra channels). You need to be 100% sure (by checking the channel
locations and visualizing them in 2D and 3D) that the locations are correct
for all your channels relative to the actual recording cap you used.

*google eeglablist + your topic for past questions/responses regarding
biosemi channels, about importing/building your channel locations, and
about adding/modifying channels/labels.

*test out for yourself how selecting a different reference "initial
channel" changes the data. I think eeglab is just asking so that it knows
which channel to label as ref, but it should be impacting processing after
that. as far as I remember, you should be able to reset the reference
"after" the basic import has been done, regardless of what you tell eeglab
upon import. Also, look through the documentation on the importer function
that you are using, there may be extra flags/settings you can use.

*double check with Biosemi that the following is really true, as it sounds
that you are using saying that Biosemi records without a reference: "BioSemi
does not require a reference choice for recording data".

*remember that many researchers don't included EOG for their ICA, so make
sure you are following guidelines from high-quality published articles on
your topic (did those researchers keep EOG channels in their ICA analysis).
After all, blink-related ICs should show up without the inclusion of EOG
channels in your ICA.
***************************************



On Thu, Nov 29, 2018 at 2:41 AM Bert Vandenberghe <
b.vandenberghe at kuleuven.be> wrote:

> Hello
>
>
>
> I use BioSemi ActiTwo System 64 electrodes + 6 additional channels (EOG1
> -> EOG6), i.e., 2 horizontal eye channels, 2 vertical eye channels and 2
> mastoid channels in order to record EEG data in the domain of ERP research
> about language learning, focusing mainly on N400 and P600 components.
>
>
>
> After having ran a pilot study, I have some questions.
>
>
>
> -          When adding channel locations, EEGLAB does not seem to be able
> to add channel locations to the six EOG channels. However, they are
> labeled/recognized correctly in the channel plots etc. Is this a
> detrimental issue for subsequent preprocessing of EEG, e.g., for ICA
> analysis? So far, I added the four eye channels in the ICA, ignored the
> warning message, but now, I doubt whether that was correct practice ?
>
>
>
> -          BioSemi does not require a reference choice for recording
> data. However, EEGLAB requires to choose a reference channel when importing
> data. Is the choice of this channel completely “free”. In other words, does
> it make a difference whether I choose Cz, Pz ,the left mastoid or any other
> channel for importing data ?Or is it better not to choose a reference
> channel for importing data that is a site of interest, e.g., Cz in the case
> language-related experiments. In both cases, I will anyhow re-reference to
> the average of scalp channels in order to follow research practice in my
> domain.
>
>
>
> Thanks for your advice on both issues,
>
>
>
> Bert
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