EEG Electrode Cap Reference electrode
mhadji05
Cyprus
in Electrodes
Hello all,
I want to make sure about the Reference electrode of the EEG Electrode Cap.
According to international system 10-20 the Reference electrode of the EEG Electrode Cap is the CPz?
Please let me know which electrode corresponds to the Reference electrode of the EEG Electrode Cap.
Thanks in advance!
Comments
From this page:
https://docs.openbci.com/AddOns/Headwear/ElectrodeCap/
Dear @wjcroft Thanks for your response.
So the answer is YES? Is Reference electrode the CPz?
Please answer me with YES or NO and if the answer is NO please tell me the electrode name-position according to international system 10-20.
Also I have another question. I saw in the guide this "The bottom BIAS pin of the Cyton board goes to the GND electrode of the cap."
What is the difference if I set GND electrode to the AGND pin on the Cyton? This is not right?
What is the use of AGND?
Thanks a lot.
Clearly the photo shows the position of the REF. Which is CPz. The GND electrode is also clearly marked. You can choose whatever positions you desire for reference. Some setups use ear lobes or linked ear lobes for reference. The later is common is neurofeedback and QEEG.
https://www.google.com/search?as_q=rereference&as_sitesearch=openbci.com
DO NOT use the AGND. This is reserved for certain applications such as active electrodes. Bias is the same as Ground.
Dear @wjcroft
Is the GND electrode, a reference electrode as well or is something else?
GND electrode is connected to Bias as mentioned in the document. Both Ground and Reference connections are used in all EEG system. Ground is NOT acting as a reference. Instead it helps to center the differential amplifiers and also provide some anti-mains (180 degrees out of phase), injection to lessen mains noise.
Ok thanks @wjcroft.
In ultracortex mark IV there are 2 earclips connected to SRB and Bias as a references. Can you explain this please?
This is just what was mentioned earlier, EEG can use different locations for Reference and Bias/Ground. Via the link previously shown, it is usually possible to 're-reference' algorithmically, to use any location as reference, given a previous reference location. Traditions such as neurofeedback, frequently use ear lobe(s) as reference, and also ground. You can do the same with the cap if you prefer.
William