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

[Makoto Miyakoshi]

Thank you Vito for your response. Forgive me to ask you one more question.

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)?

Makoto

On Mon, Jun 22, 2015 at 9:31 AM, Vito De Feo <vito.defeo at zmnh.uni-hamburg.de
> wrote:

> 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
>
> Il giorno 20/giu/2015, alle ore 00:28, Makoto Miyakoshi ha scritto:
>
> > 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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-- 
Makoto Miyakoshi
Swartz Center for Computational Neuroscience
Institute for Neural Computation, University of California San Diego
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