[Eeglablist] eeglablist

[Bert Vandenberghe]

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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