'Common' reference after biosig import of GSR, Resp and Plet

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JellinaP
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Joined: Tue Oct 19, 2021 7:22 pm

'Common' reference after biosig import of GSR, Resp and Plet

Post by JellinaP »

Hi,

We've been recording EEG (64-electrode cap), GSR, Plet and Respiration.

Although concurrently recorded and saved into one .bdf file, we are analyzing the EEG data separately from the physiology data, since the recommended re-referencing during import (via the biosig toolbox in EEGLAB) seems to impact both the EEG channels and the data from the auxiliary channels, which is not ideal.

However, when only importing the physiology data (without specifying a reference in pop_biosig), 'common' is still mentioned in the reference field of the datastructure in MATLAB (as in 'common mode', and not 'grand/common average' I suppose?). Just to be sure: it is OK to ignore this feature for the GSR, Plet and Respiration channels, right? Since the (absence of a) scalp reference should play no role during the collection of these auxiliary signals.

Thanks for your help,
Jellina

Coen
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Re: 'Common' reference after biosig import of GSR, Resp and Plet

Post by Coen »

You are correct: referencing should only be applied to the EEG channels, the sensor channels should remain unreferenced (or else the EEG reference is subtracted from the sensor channels).

Best regards, Coen (BioSemi)

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