[Eeglablist] [How to] Phase synchronization and Filter type

[arno delorme]

On 13 juin 08, at 13:28, Stanley Klein wrote:

> Arno, you say the number of cycles of EEG gamma is between 6 and 12.  
> But what about the recent Yuval-Greenberg article in Neuron pointing  
> out that the kind of gamma often found in EEG has a much broader  
> bandwidth (much fewer cycles) and is very tightly connected to an  
> artifact of microsaccades after filtering the EEG. In a previous  
> posting to eeglablist I had mentioned the poster by that group at  
> the recent Cognitive Neuroscience meeting in San Francisco. Their  
> article is now published at:
> Neuron, Vol 58, 429-441, 08 May 2008
> Transient Induced Gamma-Band Response in EEG as a Manifestation of  
> Miniature Saccades
> Shlomit Yuval-Greenberg, Orr Tomer, Alon S. Keren,Israel Nelken, and  
> Leon Y. Deouell
>
> I look forward to an interesting discussion on the topic. They are  
> clear that their conclusion is specifically for EEG, not to evidence  
> of gamma in ECoG or microelectrode studies.


According to the original reference, these "artifacts" (although it  
could also be potentially interesting to study them) mostly arise with  
nose reference data. Also, they occur very early after the stimulus  
presentation and any type of gamma effect found after 200 ms could not  
be attributed to them. There is a comment/response by P. Fries in  
Neuron too about this paper showing some genuine gamma in both MEG and  
EEG scalp recording.

As far as the number of cycle go, I am only reporting what I know  
about the literature. I agree with you that it is not because it is in  
the literature that it is necessarily optimal.

Best,

Arno
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