[Eeglablist] Plot components difference :: Help/clue Welcome

Makoto Miyakoshi mmiyakoshi at ucsd.edu
Thu Sep 17 19:19:59 PDT 2015

Dear Horacio,

I saw the jpg figures. Are these scalp topos representing ICA-derived ones?
If so, it is the ICA's polarity indeterminance issue.


On Mon, Sep 7, 2015 at 1:08 PM, Horácio Tomé Marques <ho.arts at gmail.com>

> Dear all
> some time ago (2013) we did an experiment on alpha asymmetry (EEG / EDFs).
> As part of the procedures we made the plot of the components to proceed
> with the necessary specific removal, and proceed with the rest of the
> process.
> Because this experiment proved to be very relevant and important (2015),
> we wanted to make a confirmation of the findings by doing a complete new
> analysis to the original EDFs.
> The new plots of the components have the same features/characteristics -
> as expected. But, incredibly, one of the trials (an important one) have
> three of them with, what seems to us, reversed values.
> We already have reviewed more than once the procedures and repeated the
> steps to try to understand the possible origin of the problem, but without
> success. I think we can swear that we are making the step-by-step exactly
> as in the original analysis, but as this plot always shows that difference
> something may be escaping us... is anyone able to give us a clue about what
> might be happening?
> NOTE: we even returned to the original EEGLab version (eeglab10_2_5_8b,
> including the same plug-ins, etc), because the first 2015 new ones were
> done on eeglab13_4_4b.
> Please see the links bellow with the two plots (.jpgs — 2013 vs 2015)
> where one can see that the comp1, comp3 and comp4 have the same spectral
> distribution logic, but seem to have reversed values.
> http://brainchronicles.horacioarts.com/files/Dani_2013PlotCOMP.jpg
> http://brainchronicles.horacioarts.com/files/Dani_2015PlotCOMP.jpg
> I look forward for a clue!
> Thanks for your attention.
> Best,
> Horácio Tomé-Marques
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Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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