I have a continuous resting state EEG to analyze. I've already marked as bad the bad channels and some small segments of the EEG corresponding to artefact. When I do a Welch PSD, it discarded all the segment even if only 0.15s has been selected as bad. 1) Is there another way to do a Welch PSD to use as much as possible the good signal I have?
It seems you are computing the PSD on data that has been imported (
), rather than raw data that is linked to be reviewed (
). More info about the difference in here.
https://neuroimage.usc.edu/brainstorm/Tutorials/ChannelFile#Review_vs_Import
When data is being review, it can analyzed and bad segments will be ignored. As shown in the artifact tutorial:
https://neuroimage.usc.edu/brainstorm/Tutorials/ArtifactsFilter
However, once the data is imported, if it contains on bad segment, the entire trial (or epoch) is labelled as bad. So it will not be used for further analyses.
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You are right, I did import the segment I needed to clean. After, I used review as raw. So I thought it would correct the problem.
How should I use only 12 min from a 45 min recording then?
I tried to mark bad segments and artefacts on the raw file before importing and now it is impossible to review as raw, so impossible to do PSD.
Can you tell me the steps I should have done then?
Thank you
There are at least two ways to do so.
-
In the PSD process, you can indicate set the Time window parameter to the time segment that you want to use to compute the PSD
-
You can use the process Extract > Extract time on the raw data, and indicate the Time window. This process will create a new raw condition with the desired segment. Then you can proceed with your analyses.
If you are a new Brainstorm user, we strongly recommend you start by following the introduction tutorials first (section "Get started" on the tutorial page), using the example dataset that is provided. By doing so, you will get familiar with Brainstorm features, processes and jargon.
https://neuroimage.usc.edu/brainstorm/Tutorials