[Eeglablist] Re-Referencing Question

[Dezhong Yao]

you may find a paper discussion on reference problem, 
"Physiol. Meas. 22 (2001) 693-711 
A method to standardize a reference of scalp EEG
recordings to a point at infinity", where the effect of reference and the difference between different references are intensively considered.


----- Original Message ----- 
From: "Robert Lawson" <lawson at augustmail.com>
To: "eeglablist" <eeglablist at sccn.ucsd.edu>
Sent: Thursday, June 12, 2003 4:59 AM
Subject: Re: [Eeglablist] Re-Referencing Question


> Earlier in the thread, someone mentioned the problems with ear 
> reference. I have read some theoretical papers claiming that linking the 
> ears leads to a shunt and thence to inaccurate data. However, all the 
> empirical studies I have seen found no difference between mathematically 
> and physically linked ears. Does anyone know of any empirical data that 
> shows physically linked ears are at all different from mathematically 
> linked ears?
> 
> Robert Lawson
> 
> Joseph Dien wrote:
> 
> > The only way to get an estimate of the left ear reference site 
> > activity is to compute an average reference but since, as you say, 
> > there are not enough channels, you would end up improperly imputing 
> > common activity at the recording sites to the reference site as well. 
> > If you want to rereference to a mean ear reference, you add the left 
> > ear channel to the data array (the left ear referenced to itself is a 
> > flat line of zeros) and then subtract the mean of the left and right 
> > ear channels from the entire array. You should be able to do this 
> > manually in Matlab if eeglab isn't set up to do this yet. You might 
> > want to read my paper on referencing for more info:
> >
> > Dien, J. (1998). Issues in the application of the average reference: 
> > Review, critiques, and recommendations. Behavioral Research Methods, 
> > Instruments, and Computers, 30(1), 34-43.
> >
> > Cheers!
> >
> > Joe
> >
> >     Our specific eeglab question relates to how (or maybe if), using
> >     eeglab's re-referencing pop-up window, both the above recording
> >     options
> >     could be correctly rereferenced to mathematically linked ears while
> >     obtaining/maintaining a recorded signal for all six locations Cz, C3,
> >     C4, Fz, F3, F4. The re-referencing window allows one to enter one or
> >     more (at least it appears that more than one can be used) channel
> >     number(s) for the new reference but in the above scenario (a) the
> >     left
> >     and right ears are not both available as channel numbers (for obvious
> >     reasons because Le ear was the reference).
> >
> >
> >
> > --------------------------------------------------------------------------------
> >
> > Joseph Dien
> > Assistant Professor of Psychology
> > Department of Psychology
> > 2007 Percival Stern Hall
> > Tulane University
> > New Orleans, LA 70118-5698
> >
> > Office: Room 3061
> > Phone: (504) 862-3300
> > Fax: (504) 862-8744
> > E-mail:jdien at tulane.edu
> > www: http://www.tulane.edu/~jdien/Dien.html
> >
> > Starting Fall 2003:
> > Department of Psychology
> > 426 Fraser Hall
> > 1415 Jayhawk Blvd
> > University of Kansas
> > Lawrence, KS 66045-7556
> >
> 
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