[Eeglablist] EEG Coherence

[Makoto Miyakoshi]

Dear Tahani,

Looks like your channel 1 and 2 are very much alike. Did you choose two
ICs? Did you choose subspace of alpha or mu that are similar to each other?

If there were coherence of near 1 between two ICs that do not belong to the
same subspace (and I guess that's the case here), something should be wrong
because they are far from independent. Why don't you check the setup and
tell us more detail about the comparison?

Makoto




2013/3/27 T. Almabruk <t.almabruk at yahoo.com>

>
>
>    Hi List
>
> I asked a question before about measuring EEG coherence by EEGLAB. I got
> benifits from the answer i got  but still have something wrong. I applied
> the function to the same dataset provided with EEGLAB tutorial. i filtered
> the data first and then extract the epoches (153). After that i run ICA and
> ploted component cross-coherence between channel 4 and channel 9.
> As you can see fig(1) was the result and i tried to zoom it in (fig 2).
> I wanted to compare the result with that can be done by matlab function
> (Mcoher) and fig(3) represents the results i got.
> My question is that, there is a big difference in the coherence's
> amplitude between the two functions where using EEGLAB the amplitude is
> less that 0.1 where with Mcohere as you can see is close to 1.
>
> I'm sure i miss undeerstand something because i'm new with this area and
> hope i can find some help from you .
>
> Cheers,
> Tahani
>
>
> http://www.flickr.com/photos/94417587@N05/
>
>
>
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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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