[FieldTrip] Will different EEG motages have effect on the result of granger connectivity?

[lwn_07]

Dear Jörn,

Thanks for you helping.

Weina





在 2011-9-26，17:45，"Jörn M. Horschig" <jm.horschig at donders.ru.nl> 写道：

> Dear Weina,
> 
> Basically, any montage will cause signal characteristics from the sensors used for re-referencing to show up in all other sensors. If you use a common average, the signal from any sensor will depend to some degree to any other sensor (because common average uses all sensors for rereferencing). If you use only Cz, you will obtain a high granger causality for any sensors to Cz. This would of course not reflect a real brain process, but is just the consequence of substracting the signal from Cz from all other sensors. Best would be to use a sensor that you will not include in computing granger causality (e.g. a mastoid, or choose Cz but then exclude this sensor for further analyses).
> 
> Best,
> Jörn
> 
> On 9/25/2011 7:48 PM, lwn_07 wrote:
>> 
>> Thanks Jan-Mathijs.  Does it mean if I selected my data segment from mono montage （reference to mastoid), i'd better  calculate the granger causality in mono montage?  Some paper selected Cz as reference, is that OK?
>> 
>> Best regards.
>> Weina   
>> 
>> 发自我的 iPad
>> 
>> 在 2011-9-25，23:36，jan-mathijs schoffelen <jan.schoffelen at donders.ru.nl> 写道：
>> 
>>> Hi Weina,
>>> 
>>> Yes, granger causality results will for sure change when you use different montages. When you replace each measurement (what you call 'mono-montage') with that measurement minus the average across the whole recording array (what you call 'average montage') the amount with which signals can be explained in terms of their own and the other signals' past will change as well. This most likely leads to 'granger causality' estimates which just reflect spurious interactions.
>>> 
>>> Best wishes,
>>> 
>>> Jan-Mathijs
>>> 
>>> On Sep 25, 2011, at 1:42 PM, 李卫娜 wrote:
>>> 
>>>> Dear all,
>>>>   Is anyone knows about that wether different EEG motages (such as mono-motage or average montage) have effect on the result of granger connectivity?
>>>>  
>>>>                                                                                                          Weina
>>>> _______________________________________________
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>>>> fieldtrip at donders.ru.nl
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>>> 
>>> Jan-Mathijs Schoffelen, MD PhD 
>>> Donders Institute for Brain, Cognition and Behaviour, 
>>> Centre for Cognitive Neuroimaging,
>>> Radboud University Nijmegen, The Netherlands
>>> J.Schoffelen at donders.ru.nl
>>> Telephone: +31-24-3614793
>>> 
>> 
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>> 
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> 
> 
> -- 
> Jörn M. Horschig
> PhD Student
> Donders Institute for Brain, Cognition and Behaviour 
> Centre for Cognitive Neuroimaging
> Radboud University Nijmegen 
> Neuronal Oscillations Group
> 
> P.O. Box 9101
> NL-6500 HB Nijmegen
> The Netherlands
> 
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> Tel:    +31-(0)24-36-68493
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> 
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