PSD units at the sensors and the sources

Discussions
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1

Hello,

I have a question regarding PSD units.

I performed a PSD using Welch method at the sensor and at the source level. However, I'm wondering what are the exact units to be displayed on the colorbar. I saw the PSD units are T^2/Hz, but the different orders of magnitude between sensors and sources make me wonder if I'm misunderstanding something.

Thanks for your help.

Pictures:
Left at the sensor level, right at the source level:

Screenshot 2021-07-08 at 01.57.50
Screenshot 2021-07-08 at 01.57.501049×475 285 KB

2

The PSD values, when displayed as power, are in (signal units)^2/Hz, indeed.

MEG sensors: 500 fT = 5*10^-13 T => PSD in the range of 10^-26
What you observe is correct.

For the sources, it depends on the measure that is used.
I guess what you used here is dSPM?

3

Yes. You are right. I used dSPM.