Artifact detection based on peak-to-peak amplitude

Discussions
1

Dear Francois,

I preprocessed and epoched my EEG data. Now I would like to detect the channels contain peaks exceeding -100 and +100 micro volt and reject those channels.

In the tutorial I found brief information regarding “Artifacts > Detect bad channels: peak-to-peak” (http://neuroimage.usc.edu/brainstorm/Tutorials/TutRawAvg), which I think it is what I am looking for. But I have a question about that window:

In front of “EEG:” shall I insert “-100” and “+100”? Or I should insert “0” and “100”? Or “0” and “200”? In another word, is it one-directional (-100 to +100) or two-directional (0 to 100) or based on absolute (0 to 200)?

Or if this is all incorrect and there is another way, I would be grateful if you advise me.

Best,
Mojtaba

2

Hello,

As the legend says, the first value is the detection threshold. It allows the detection of flat channels (no data recorded). If you don't want to use this, set it to 0.
The second value is the rejection threshold, as a peak-to-peak value. If you set it to 100uV, it will reject the signals that have a maximum peak-to-peak amplitude above 100uV (from the min to the max, for instance from -50uV to +50uV).

We actually don't think this is an appropriate way to detect and reject artifacts. Those tutorials are now a bit outdated.
We are currently working on a new set of tutorials, all the pre-processing sections are almost ready:
http://neuroimage.usc.edu/brainstorm/TutorialsNew

Cheers,
Francois