how to tell whether the EEG data is correct?

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Yueqing Li
Posts: 51
Joined: 08 May 2007, 16:41

how to tell whether the EEG data is correct?

Post by Yueqing Li » 08 Aug 2007, 18:01

Hello, Dr. Schalk:

I am trying to use the real-time EEG display and/or the Maxifred tool to assess signal quality. I think that is a great idea. But I am just not sure what property a high quality EEG data should have? So, where can I find some standard of high quality EEG data?

Thank you very much.

gschalk
Posts: 615
Joined: 28 Jan 2003, 12:37

EEG signal quality ...

Post by gschalk » 08 Aug 2007, 20:36

Yueqing,

This is a difficult question with no simple answer. However, here are a few guidelines:

1) You do not want slow drifts in the EEG. Look at your data files and you will see these slow drifts in some files. The simplest cause of such drifts are when you start the system. Wait until the signals have settled in before you press Start.

2) You do not want a lot of 60 Hz noise. If you have a lot of 60 Hz on certain channels, fix these channels. If you have a lot of noise on all channels, fix the ground and reference.

3) You do not want a lot of EMG that comes from people, e.g., clenching their teeth, or EOG from eye movements/eye blinks. Simply ask the subject to do these tasks, and you will see what this looks like. You should also look at Dennis McFarland's talk in the Workshop Tutorial to the first BCI2000 Workshop two years ago. It comes as a PDF with the BCI2000 Installation.

Gerv

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