[Eeglablist] reference during import of EMG data acquired with Biosemi

[seba]

Dear eeglab specialists,

I hope you can help me on this one:

I have recorded facial electromyography (EMG) with a Biosemi system, and want to analyze it in EEGLAB/matlab.
I am not sure about the question of the reference during importing.

I know that when first importing EEG data into EEGLAB, which was recorded reference-free with with a Biosemi system (www.biosemi.com), one should indicate whatever channel as a reference, in order to improve the signal-to-noise ratio.

However, it is unclear to me what I should do when importing into EEGLAB EMG data recorded with the same system.
Should I indicate one electrode as a reference? And after having done so, should I rereference the data? to what?
Or is the EMG signal so strong that one can afford to keep some noise in the data and therefore does not need to indicate a reference during importing?
Would this also be true if I am interested in tiny EMG differences between conditions, as usual in facial mimicry paradigms?

Thank you very much for your help.

Best,
Sebastian



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Sebastian Korb, Ph.D.
Swiss Center for Affective Sciences
University of Geneva, Switzerland
Tel.: +41223799812
Email: Sebastian.Korb at unige.ch
Webpage: http://www.affective-sciences.org/user/34





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