[Eeglablist] Re-referencing & channel names

[Curtis Bingham]

Folks, 
Must you re-reference to perform ICA? 
And if so, how do you re-reference to linked-ears? 
How do you change the channel labels from a dataset? 
 

1.) We’re getting up to speed using eeglab. We’re recording in 19 channels with a linked-ears reference. The tutorials and Arnaud’s video overviews talk about re-referencing regularly. Must you re-reference to perform ICA? If the data were collected using linked-ears is there any reason to re-reference the data, assuming we’re not examining a very localized trouble-spot?  Or can the data be used as-is, without re-referencing?  

 

2.) If we must re-reference, how do you do so with linked-ears?  Are A1 & A2 equivalent to T9 & T10? The literature shows an average reference is inaccurate unless you have very high-density coverage (i.e. more than 19 channel cap). We don’t yet have the understanding to do REST. Is it sufficient to manually create two new channels in our data via the Channel Locs window to represent mastoid placement, and modify the channel locs (.ced) file to append to it the dimensions for T9 & T10? Or is there an equivalent polar dimension for A1 & A2?

 

3.) How do you change the channel labels from a dataset? We’re recording with a NeuroField Q20 19-channel device. The output EDF file names channels with prefix & suffix that need to be modified before channel locations are set. Names are of the format EEG-ZZ-LE, where ZZ=traditional 10-20 sites. Presently we’re manually deleting both EEG- prefix and -LE suffix and it is time-consuming. Is there an easy way to pre-process the EDF file to strip these extra characters?