Hello,
Recently, during the EEG signal recording, a low-frequency fluctuation with a very high amplitude, as shown in the attached video, is added to the EEG signals. It suddenly appears during the recording and usually lasts for several minutes and after that gradually disappears.
This noise is observed in most of our participants during both eye-open and eye-closed rest conditions.
In our previous recordings, we did not deal with this noise. Recently we have encountered it. According to our investigation, no new electromagnetic device has been put around the recording room. We could not find where this noise is coming from.
I am wondering if anyone can help me to find the possible origins of this noise?
Hi Golnaz Baghdadi
What range of highpass and lowpass filter do you specify in your current recordings?
Hi,
To me it looks like a "sweat" artifact- electrodermic activity that can be seen when a subject experiences discomfort, usually due to excess of heat and/or humidity. You could try cooling the subject using a fan or adjust air conditioning.
Hi Alice Robert
Thank you very much for your answer. I will try your suggestion. I hope the problem is solved.
Hi Dr. Baghdadi,
The following paper might be of help.
"Paroxysmal slow cortical activity in Alzheimer’s disease and epilepsy is associated with blood-brain barrier dysfunction"
Dear Sheida,
Thank you for your answer. I don't think it is something related to cortical activities.
Since changing the recording room to a room with a proper air conditioning system solved the issue, "sweat" artifact- electrodermic activity mentioned by @Alice Robert is more likely to be the source of that noise.
Alice Robert seems to be right. Did you check room temperature during the exams?
We did not measure the temperature of the room during recording. But feelings of warmth have been reported in some records by participants.
Hi Dr. Baghdadi,
I also sometimes saw this noise when I was recording my signals in the summer. It seems that it is due to sweat and humidity on the surface of the scalp and I hope the problem will be solved.
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