[Eeglablist] Hilbert

Ernesto Pereda eperdepa at ull.es
Mon Nov 7 01:23:50 PST 2005


Dear Peter:

A review article which touches upon this subject is about to appear in Progress
in Neurobiology. You can download a preprint from

http://arxiv.org/abs/nlin/0510077

I apologize in advance for the self-promotion.

> Dear Peter,
>
>
>
> There are plenty or articles about phase locking. You could look it up in:
>
>
>
> Tass, P., Rozenblum, M. G., Weule, J., Kurths, J., Pikovsky, A., Volkmann, J.,
Schnitzler, A., and Freund, H.-J., "Detection of n:m phase locking from noisy
data: application to magnetoencephalography," Phys.Rev.Lett., vol. 81, no. 15,
pp. 3291-3294, Oct.1998.
>
> and in several other articles from Pikovsky and Rosenblum. There is also a
book chapter from them about this matter (unfortunately I forgot the title, but
you can search for it using the names).
>
>
>
> Technically, you can transform data by using standard hilbert() function in
Matlab. The output is the analytical signal which is complex-valued and has some
special properties. The instantaneous phase of a complex-valued signal can be
computed by angle() or imag(log()). Then you may want to quantify the phase
difference by using the phase locking index gamma:
>
>
>
> gamma = abs(mean(exp(i*PhaseDiff)));
>
>
>
> However, there are other indices for that as well. It is advised to narrow
band filter data, and to take care of boundary effects when you cut it into
epochs . All this things are described in literature.
>
>
>
> The best way to use this method is when you are interested in phase
relationships rather than in amplidutes. It can be usefull when you study
(chaotic) oscillatory systems.
>
>
>
> Regards,
>
> Andrei
>
>
>
>     -----Oorspronkelijk bericht-----     Van: eeglablist-bounces at sccn.ucsd.edu
namens Lin, Peter (NIH/NINDS) [F]     Verzonden: di 1-11-2005 20:18     Aan:
eeglablist at sccn.ucsd.edu     CC:     Onderwerp: [Eeglablist] Hilbert
>     
>     
>
>     Hi I am working with movement data (finger abduction and sequence) with
EEG and studying phase lag and coherence.  Is there any way to use EEGlab to
Hilbert transform the data?  What is the best way to study phase locking using
this technique?  Any help would be appreciated

>
>     
>     Thanks
>
>     
>     peter
>
>
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>  
>


-- 
Dr. Ernesto Pereda
Electrical Engineering and Bioengineering group
Dept. of Basic Physics
College of Physics and Mathematics
University of La Laguna
Avda. Astrofísico Fco. Sánchez, s/n
38205, La Laguna, Tenerife, SPAIN
e-mail:eperdepa at ull.es
Phone: +34 922318654
Fax: +34 922318228
web: http://webpages.ull.es/users/eperdepa



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