[Eeglablist] Weakened signal at Pz electrode

[Dezhong Yao]

Dear all
 IF the "reference" is close to Pz, the signal will be very small.
 A  proper way to remove the unknown but always existed non-zero  "reference effect" is to adopt the general zero-reference by a free software (REST at:  http://www.neuro.uestc.edu.cn/rest/ ), which may translate any data to zero-reference. 
  certainly, if you meet any problem in using the software, you may cotact us.
------------------	
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
http://www.neuro.uestc.edu.cn/bci/member/yao/yao.html
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
2015-05-13
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发件人：Roni Shafir
发送日期：2015-05-13 04:58:28
收件人：eeglablist
抄送：
主题：[Eeglablist] Weakened signal at Pz electrode

Hi all,
We are using BioSemi in our experiments and recently moved from 64
electrodes to 32 electrodes.
We are still using the 64 electrode caps.
Something very strange that I noticed is that since we moved to 32
electrodes, Pz electrode has a very low (kind of flat) signal, as apposed
to what I used to see when we used 64 electrodes.
What could be the problem? I thought it may be related to the recording
system or the online reference.
Importantly, there is no problem with the electrode because I used
different sets and this pattern remained unchanged.
Did anyone have this problem already?
Would appreciate your help.
Roni

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