[Eeglablist] phase synchronization of EEG in eeglab

[Yaseen Gerhold]

It is a very interesting method which one of my lab mates and I have
implemented. It's not too difficult to code if you know the basics of
wavelets i.e., how to extract instantaneous phase and amplitude. You could
alternatively use a Hilbert transform to extract the phase and amplitude
from the signal, however, there is some debate around which methods yields
the best estimation of phase. Lachaux et al. (1999) used wavelets, I'm
inclined to this approach. Beware, it can take some time to compute, due to
the significance testing when you use a number of electrodes pairs.

gtec has implemented this in their gbanalyse software, I'm not sure if
there is a demo version available. Perhaps check with gtec? Alternatively,
EEGLAB has a number of coherence/synchrony measures (Channel/Channel
Coherence). As far as I am aware you can calculate phase coherence based on
wavelets as opposed to fft based approaches. Whether this is an exact
implementation of Lachaux you will have to check. I think they use
bootstrapping where Lachaux et al., (1999) uses surrogate data or
randomisation. I'm sure Makoto can confirm?


On Tue, Jun 19, 2012 at 6:16 PM, Angel Tabullo <angeltabullo at yahoo.com>wrote:

> Does anybody know if there's a way to calculate EEG phase synchronization
> with EEGLAB? I want to run the analysis described in Lachaux (1999) (
> http://www.ma.utexas.edu/users/davis/reu/ch3/cwt/lachaux.pdf), but I
> found a paper saying that this function had not been included in eeglab yet
> (Delorme and Makeig, 2004) (
> http://sccn.ucsd.edu/eeglab/download/eeglab_jnm03.pdf). The paper is
> probably outdated, but I haven't found anything like this function in the
> newer versions. If it can't be done with EEGLAB, does anybody know any
> alternative software or script that might do it?
>
> Thanks for your useful comments, as usual.
>
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