[Eeglablist] Effect of anti-aliasing low-pass filter on connectivity analysis

[Vito de Feo]

  Dear Makoto,
if you are using non parametric directionality methods (i.e.
cross-correlation) you can filter as you want, just use filtfilt and eeglab
uses filtfilt.
If you are using parametric methos (i.e. Granger with SIFT) than is better
don't filter and use just cleanline for 50 Hz (or 60Hz in USA) and a very
broadband low pass filtering (as Anil Seth write in several papers). This
low pass filter has to be very far from the band of interest. So if you
want respect the Luck raccomandation on anti-aliasing filtering use an
higher rate, maybe 500 Hz if you can. If you can't the Anil Seth
reccomandation has the priority on the anti-aliasing reccomandation.
Consider to use unfiltered and not downsampled signal.
Let me know if you have more questions.
Vito

"Dijk, BW van" <bw.dijk at vumc.nl> ha scritto:

> Dear Makato,
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>    This depends on the connectivity measure that you wish to apply.
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>    Phase dependent measures or cross-frequency measures are strongly
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>    If you use those than stay away from your sampling rate
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>    The 1/3 or ¼ of the sampling frequency as a limit –in stead of the
> Nyquist criterium- is more safe
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>    Regards
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>    Bob van Dijk
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>    VAN: eeglablist-bounces at sccn.ucsd.edu
> [mailto:eeglablist-bounces at sccn.ucsd.edu] NAMENS Makoto Miyakoshi
> VERZONDEN: dinsdag 23 juni 2015 23:07
> AAN: Vito De Feo
> CC: EEGLAB List
> ONDERWERP: Re: [Eeglablist] Effect of anti-aliasing low-pass filter on
> connectivity analysis
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>     Thank you Vito for your response. Forgive me to ask you one more
> question.
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>       As the ERP handbook by Luck (or his other book) recommends,
> anti-aliasing should better have the margin of 4-5 times of the new
> sampling rate e.g. if you downsample signlas to 250 Hz, anti-aliasing
> low-pass at 125 Hz is the standard, but recommendation is 75 Hz or even
> 50 Hz. Well, I haven't tested it myself so I am not sure what bad it
> would do if I use 125 Hz (any comment on this, anyone?) but in this
> case, I guess the anti-aliasing low-pass filter does affect the
> subsequest connectivity analysis--am I correct (assuming that I analyze
> EEG up to 50 Hz)?
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>      Makoto
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>      On Mon, Jun 22, 2015 at 9:31 AM, Vito De Feo
> <vito.defeo at zmnh.uni-hamburg.de> wrote:
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>      Dear Makoto,
> this will not affect the connectivity analysis if the frequency of
> interest are far from the Nyquist frequency. For example if you
> downsample to 500 Hz (Nyquist freq = 250 Hz) you will have no problem in
> the band 0-100 Hz.
> Best
> Vito
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> Il giorno 20/giu/2015, alle ore 00:28, Makoto Miyakoshi ha scritto:
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>> Dear List,
>>
>> If I use zero-phase low-pass filter for anti-aliasing, does it affect
>> the subsequent connectivity analysis? I ask this because EEGLAB
>> pop_resample() automatically applies it. If it does, is there a
>> workaround? Should I use minimum phase causal filter for anti-aliasing?
>>
>> --
>> Makoto Miyakoshi
>> Swartz Center for Computational Neuroscience
>> Institute for Neural Computation, University of California San Diego
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>     --
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>      
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>       Makoto Miyakoshi
> Swartz Center for Computational Neuroscience
> Institute for Neural Computation, University of California San Diego
>
>        



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Pflichtangaben gemäß Gesetz über elektronische Handelsregister und Genossenschaftsregister sowie das Unternehmensregister (EHUG):

Universitätsklinikum Hamburg-Eppendorf
Körperschaft des öffentlichen Rechts
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Prof. Dr. Burkhard Göke (Vorsitzender)
Prof. Dr. Dr. Uwe Koch-Gromus
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