[Eeglablist] Reference electrode and coherence

Dezhong Yao dyao at uestc.edu.cn
Sat Mar 21 04:01:44 PDT 2015

Dear Salim,
     The best answer to your concern is explored in the following nice paper:
Marzetti, L., Nolte, G., Perrucci, M.G., Romani, G.L., & Gratta, C.D.(2007). The use of standardized infinity reference in EEG coherency  studies.
Nueroimage.  36,48-63.  
     It indicated that coherence is disturbed by both volume conductor effect and non-zero reference, the imaginary coherence (iCoh) is adopted to reduce the effect of volume conductor, and the new technique --REST (reference electrode standardization technique)  (free software is available at www.neuro.uestc.edu.cn/rest ) is adopted to get the approximate zero-referenced EEG data, thus greatly reducing the effect of non-zero reference.
   best wishes

From: eeglablist-bounces at sccn.ucsd.edu [eeglablist-bounces at sccn.ucsd.edu] on behalf of Salim Al-wasity [salim_alwasity at yahoo.com]
Sent: Wednesday, September 10, 2014 6:00 AM
To: eeglablist at sccn.ucsd.edu
Subject: [Eeglablist] Reference electrode and coherence

Have a nice day.
According to (Guevara 2005, Fein 1988 and others), Coherency (especially imaginary coherence) might be affected by EEG reference electrode.In my study, an average reference is used and an imaginary coherence (iCoh) is calculated for the components of the averaged EEG signal.Is the averaged reference or the ICA affect the phase of the EEG signals, and hence affect the coherency?
Salim Al-Wasity
Eeglablist page: http://sccn.ucsd.edu/eeglab/eeglabmail.html
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For digest mode, send an email with the subject "set digest mime" to eeglablist-request at sccn.ucsd.edu----------------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
尧德中 电子科技大学 生命科学与技术学院/信息医学研究中心/神经信息教育部重点实验室/神经信息国际联合研究中心
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