How to interpret evoked.plot_joint graph?

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Hi,

I am doing the of the eeg data. I plotted the evoked.plot_joint() and got the following image.

jointplot

I know that the plot shows the 3 local maxima for global field power. My question is:

  1. What does -.2 and .5 signify?
  2. what else can we deduce from this graph?
  3. What kind of comparisons can be done from the 2 joint plots of 2 subjects?

Any help is greatly appreciated. Thanks

Any

2

Hello!

You mean on the abscissa? It’s right there in front of you: the abscissa label is “Time (s)” :slight_smile:

Probably that no baseline correction has been applied, hence the traces are “all over the place” across the entire time range.

You could, for example, see whether the extrema of the GFPs occur at roughly the same times, and in theory also whether the respective topographic maps look similar (however, I see that the maps are not really useful in your case here – not sure if this is expected or a bug!)

Best wishes,
Richard

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3

Thanks for your help. In this case, I found out that one epoch is in the time range from -.2 to .5. I am guessing that -.2 signify resting state?

4

You’re looking at an evoked object here, not at a single epoch! In fact, you’re looking at the average of 999 epochs (see the Nave in the top left)

What you’re seeing here depends on what you were measuring … when epoching, time point 0 corresponds to an experimental event, and negative time, therefore, to the time period directly before this event. If you have “actual” events in your experiment (e.g., you’re displaying an image, or playing a sound), then the negative-time period would simply be the pre-stimulus period. This, then, would have nothing to do with a resting-state recording.

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