[Eeglablist] Re-reference average reference
David G Gilbert
dgilbert at siu.edu
Thu Jun 4 21:12:47 PDT 2015
Once we have changed the original 19-channel data reference from linked ears to average reference, does rejecting components create a problem if the components include the linked earlobes once we re-rereference that data after cleaning back to linked ears? We have the following questions concerning this double-re-referencing question. Here are some of our thoughts.
We have been working on the referencing issue with MATLAB (referencing to average reference while retaining "LE"-linked earlobes). We have explored many different options but have come to no solutions to a potential problem. Our potential problem is that we have not been able to avoid including the LE as part of the average reference and part of the ICA without MARA crashing. I would assume that this would likely not cause any problems for us as the only purpose of our average reference is ICA, and our only purpose for ICA is removing eyeblinks/lateral eye movement/EKG/EMG. However, because the LE is included in the average reference, it is technically possible that removal of components could affect the LE data in marginal ways(i.e. removal of frontal eyeblinks or BSS may or may not affect LE and therefore affect our LE reference). We have been unable to alter this in any way, however, the flip-side of this would be that IF LE was altered by MARA(i.e. cleaned up by MARA) it may even make for a cleaner initial reference and might not be a bad thing at all. Please let us know your thoughts on this as we have come to a standstill on how to deal with this potential problem or if we should just move ahead including the LE in the average reference and then referencing back to LE after ICA/MARA/CORRMAP are completed.
Any answers would be appreciated,
From: eeglablist-bounces at sccn.ucsd.edu <eeglablist-bounces at sccn.ucsd.edu> on behalf of Dezhong Yao <dyao at uestc.edu.cn>
Sent: Wednesday, June 3, 2015 7:29 PM
To: Ahmed Almurshedi; EEGLAB List
Subject: Re: [Eeglablist] Re-reference average reference
The earlobe reference may have a distinct effect on the earby channels, and average reference may also shift the data of all the channels.
The best choice in physics is a zero reference, now there is a free software -REST which can transform a earlobe reference or average reference or any other reference to the idea zero reference. You may find this software at:
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>From:"Ahmed Almurshedi" <ahmed19875000 at yahoo.com>
>To:"EEGLAB List" <eeglablist at sccn.ucsd.edu>
>Subject:[Eeglablist] Re-reference average reference
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Dezhong Yao PhD
Cheung Kong Professor of Neuroengineering, Neuroimaging
E-mail: dyao at uestc.edu.cn
Fax: 86-28-83208238; Tel: 86-28-83201018
Director, Key Laboratory for NeuroInformation, Ministry of Education, China
International Joint Research Center for NeuroInformation, Ministry of Science and Technology, China
Dean, School of Life Science and Technology, University of Electronic Science and Technology of China, Sichuan,Chengdu 610054, China
Director, Center for Information in BioMedicine, University of Electronic Science and Technology of China, China
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