[Eeglablist] Hilbert

[Arnaud Delorme]

Lin, Peter (NIH/NINDS) [F] wrote:

> 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?
>
EEGLAB does not support Hilbert transforms, but the signal processing 
toolbox has a built-in "hilbert" function. The advantage of the Hilbert 
function is that it returns more accurate phase information that 
standard time-frequency transforms. The drawback is that you are usually 
not allowed to visualize results of hilbert transform at different 
frequencies (although you may bandpass the signal at the frequency of 
interest and then apply an hilbert transform). If anyone has functions 
to compute hilbert transform of the EEGLAB structures, we would for sure 
be interested in helping make them avaiable as a plugin.

The following paper basically shows that Hilbert and standard wavelet 
methods are roughly equivalent:

Comparison of Hilbert transform and wavelet methods for the analysis of 
neuronal synchrony
J Neurosci Methods. 2001 Oct 30;111(2):83-98.
Michel Le Van Quyen, Jack Foucher, Jean-Philippe Lachaux, Eugenio 
Rodriguez, Antoine Lutz, Jacques Martinerie and Francisco J. Varela

Best,

Arno

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