What is the unit for the source estimates returned by apply_inverse_epochs function for EEG data?

[dahaiyu]

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What is the unit for the source estimates returned by apply_inverse_epochs function for EEG data?

For example, what should be the units of the ordinate in the figure above?

[richard (Richard Höchenberger)]

Hello @dahaiyu and welcome to the forum!

The dSPM and sLORETA algorithms produce source estimates in unit-less values (based on F-statistics).

On the other hand, the MNE and eLORETA algorithms return the electrical current in Ampere meters (that’s why the numbers are so tiny!).

It is therefore totally alright to label the y-axis in your above figure as “dSPM value”.

Hope that helps!

Richard

[dahaiyu]

Thank you @richard . So, all computation in EEG source space based on dSPM and sLORETA are almost unit-less, for example, source power based on dSPM value, as follows.

Do I understand it correctly?

[richard (Richard Höchenberger)]

@dahaiyu

So, all computation in EEG source space based on dSPM and sLORETA are almost unit-less,

Yes, anything derived from the dSPM and sLORETA scores doesn’t inherit any units from those scores (as they are unitless)

[dahaiyu]

OK, thank you very much @richard .