[Eeglablist] automatic epoch rejection

[Brion Woroch]

Thanks Manos,
You are correct, but setting a low threshold also seems to detect  
things that are not eyeblinks, such as alpha noise, fluctuating  
channels, HF noise, etc.   When I set a low threshold for detecting  
eyeblinks and it seems to detect them just fine.  However, it also  
marks any epoch for rejection in which any one of the scalp channels  
fluctuates above that threshold.  I am looking for a way to either  
restrict the thresholded fluctuation detection to the EOG channels or  
set a low threshold to EOG channels and a less conservative threshold  
to the scalp electrodes.
Brion

On Oct 22, 2008, at 4:51 PM, Klados Manousos wrote:

> Dear Brion
>
> If you search in literature there exist a certain paper which  
> suggest that eye blink's voltage is larger than 50 ΞΌV. So you can  
> put a threshold of 50ΞΌV for eye blinks. If i understand you you  
> need an automatic procedure to reject contaminated epochs. One very  
> easy algorithm is to find epochs with values larger than 50 ΞΌV and  
> exclude them for your study. I can't understand the reason you need  
> different threshold for different channels. You can indetify  
> contaminated epochs from one signal and in the others the epochs  
> have to be the same...correct me if i uderstood wrong.
>
> Greetings
> Manos
>
> 2008/10/22 Brion Woroch <bworoch2 at illinois.edu>
> Hello,
> I am looking for a way to set the threshold for  the "detection of
> extremely large fluctuations" in the automatic epoch rejection
> differentially for different channels.  I would like to set one
> threshold for EOG channels and another for scalp electrodes.  Does
> anybody know how I can accomplish this?  Thanks in advance.
> Brion Woroch
>
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>
> -- 
> Klados A. Manousos
> Graduate Student, Research Assistant
> Lab of Medical Informatics, Medical School
> Aristotle University of Thessaloniki
> Thessaloniki, Greece
> _________________________________________________
> Tel: +30-2310-999332
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>

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