Query about sLORETA data analysis in MEG

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Dear Brainstorm Community,

I'm currently working on analyzing MEG data from a speech-in-noise task, and I've encountered a couple of questions regarding my data processing. I hope someone here can provide some insights.

  1. Units in sLORETA Averages: I've conducted sLORETA analysis on my data, and when I averaged the results from individual runs for each participant, I noticed that the units changed. The averages of individual runs are unitless, but when I combine all runs for one participant, I now have units in pA.m (picoampere-meters). Is this expected or is there a step I might be missing to maintain consistency in units?
  2. Projection on Default Anatomy: I used a common anatomy and individually warped it based on the head points for each subject. I'm wondering whether I should project the sLORETA results back onto the common anatomy, given the individual warping. Does this projection step make sense in my data analysis pipeline?

Any insights or suggestions would be greatly appreciated. Thank you in advance for your help!

Best regards,
Maxime

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  1. Units in sLORETA Averages:

None, this is not expected, and there is not a missing step.
It was a visualization issue, the average is also unitless. This is corrected in commit df41794
Update your Brainstorm instance to have the fix.

  1. Projection on Default Anatomy:

No, sources obtained for warped anatomies should not be projected. Check this link for more details:
https://neuroimage.usc.edu/brainstorm/Tutorials/CoregisterSubjects#Warped_brains

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Hi Raymundo,

Thank you for your reply and help, it is much appreciated. I've completed the update successfully, and it seems to have fixed the unit issue in the sLORETA average. However, there's still a minor visualization issue when examining the time-course of a scout. Please take a look at the image below for a visual representation of the issue

Screen Shot 2023-11-02 at 9.02.49 PM
Screen Shot 2023-11-02 at 9.02.49 PM1920×1028 194 KB

Thanks,
Maxime

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Hi Maxime,

This is now fixed.
Please update your Brainstorm instance.

5

Hi Raymundo,

Thank you very much for your quick reply and help. When I try to view the time-course of a scout, I now get the following error:
Screenshot (1)

Best,
Maxime

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Please update and try again

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Everything looks good now, thanks!