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I have written a lot and talked a lot about the series of articles on EEG tutorials. You can refer to the gitbook website I made, https://book.7988888.xyz/ ,
I have also talked about the reference point electrode many times in my previous articles. You can refer to the previous articles " Selection and Conversion of EEG Reference Electrodes" , " Reference Electrode Transformation for EEG Analysis " and "The Average Reference of EEG Reference Points" , Although so much has been talked about, the methods of EEG technology are really diverse and colorful, so there is no absolute standard for learning EEG technology, and a deep understanding of it is the best way to master it.
Today, what we are going to talk about is also the EEG data preprocessing process. One operation is very simple, but the theory is a very important step-the EEG reference electrode. Reasonable reference methods are also an important reason for subsequent interpretation of results.
Reference Electrode Standardization Technique (REST)
The well-known EEG reference is to find the neutral electrode point on the surface of our head or body or the real potential zero point, but such electrodes are basically impossible to have, and the electrical signals we collect, It is actually a voltage (potential difference) signal, and the most basic formation must be the difference between the two electrode signals, so when determining the reference electrode, it is better if the value of the original electrode signal is not affected. The traditional method is to find the corresponding potential zero point, such as bilateral mastoids, nose tip, etc.; another method that high-density leads will do is to use the average reference (theoretically, the sum of the spheres is zero).
Domestic Yao Dezhong proposed the REST zero reference technology in 2001, and introduced the REST technology on its official website as follows:
Refer to the official website: http://www.neuro.uestc.edu.cn/name/shopwap/do/index/content/96
REST is a re-referencing technique, a software method for referencing a multi-channel spontaneous EEG or event-related potential at any one physical point on the brain/body surface, or at the mean or connected ear The postprocessed data etc. are transformed into a new dataset where the potential is zero/constant. ——The translation may be slightly wrong, for reference only
REST (Reference Electrode Standardization Technique) is a re-reference technique, a software method for translating multichannel spontaneous EEG or event-related potentials with reference at any a physical point on brain/body surface or the post-processed data referenced at average or linked ears etc to a new dataset with reference at Infinity where the potential is zero/constant.
——From Baidu Encyclopedia, for reference only
The conversion formula has been introduced in the second paragraph of the above figure.
The head surface signal Vr under any reference is generated by the intracranial source X, and the head surface signal V0 can be reconstructed by reconstructing the equivalent source X
——The picture comes from the CSDN network: https://blog.csdn.net/Kobe123brant/article/details/111631475
The disadvantage is the choice of the head model, since it uses the activity signal of the source X, then the volume conduction problem is a very important process, and a suitable head model will be very important to the method.
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Author of this article: Chen Rui
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