[Eeglablist] Dipolar components

[Makoto Miyakoshi]

Dear Ali,

The scalp maps of ICs directly reflects the columns of mixing matrix (i.e.
EEG.icawinv).
See slide 14: 'How does ICA model physiology' (from EEGLAB workshop 2017 at
Mysore)
https://sccn.ucsd.edu/mediawiki/images/7/74/IcaDecompositionOfEegData4.pdf

Therefore, if you see nice dipolar scalp maps, it means that ICA (which
does not know anything... it does not know channel locations, does not even
know the signal is EEG!) identified theoretical electrophysiological
property of EEG (see Nunes books about it).

> Is it just the smoothness of the scalp maps that determines capacity to
fit dipoles?

No, not the smoothness. It's dipolarity. See Delorme et al. (2012) PLoS One
paper.

Makoto

On Sat, Jan 28, 2017 at 12:00 PM, ali zahedi <ali.zahedi.bham at gmail.com>
wrote:

> Dear all,
>
> Regarding the dipole fitting to the ICs and dipolar components, what are
> the properties of the scalp maps of the ICs that can fit with a dipole with
> less than a residual variance? Is it just the smoothness of the scalp maps
> that determines capacity to fit dipoles?
>
> I really appreciate it if you could help me with this.
>
> Regards,
> Ali
>
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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