[Mne_analysis] Interpretation of zero/signs in source current estimations

[Denis-Alexander Engemann]

Hi Andy,

2014-10-01 19:40 GMT+02:00 <acgt2 at cam.ac.uk>:

> Dear MNE users
>
> This might have come up before, but I have a bit of an interpretation
> question - when the source current is estimated, what would ‘zero’ in the
> .stcs mean?
>

do you mean literally zero?
Do you talk of individual source estimates or did you morph the estimates
to the average brain?

-Denis

Should it be interpreted as an absolute value, where no current is moving,
> on average, in or out of the scalp at that source, or it is relative to
> some reference current?
>
> I was under the impression that it was some sort of absolute value (ie ‘on
> average, the net movement of positive ions moving towards or away from the
> scalp is zero, in this source’). Then a positive current value (in a
> particular source) should be interpreted as the average charge flowing one
> way (into the scalp? out?) and negative current values meant it was, on
> average, flowing the other direction. But a colleague today suggested that
> the zero was relative to a reference: that, due, to neural physiology,
> there is always an average positive current inwards/outwards, and it is to
> this ‘baseline’ rate that the ‘zero’ is aligned to.
>


> Does anyone have any thoughts on which is the correct interpretation?
>
> Thanks,
>
> Andy
>
>
>
> _______________________________________________
> Mne_analysis mailing list
> Mne_analysis at nmr.mgh.harvard.edu
> https://mail.nmr.mgh.harvard.edu/mailman/listinfo/mne_analysis
>
>
> The information in this e-mail is intended only for the person to whom it
> is
> addressed. If you believe this e-mail was sent to you in error and the
> e-mail
> contains patient information, please contact the Partners Compliance
> HelpLine at
> http://www.partners.org/complianceline . If the e-mail was sent to you in
> error
> but does not contain patient information, please contact the sender and
> properly
> dispose of the e-mail.
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://mail.nmr.mgh.harvard.edu/pipermail/mne_analysis/attachments/20141001/0b2b00f9/attachment.html