[FieldTrip] Correction baseline : removing the mean value or high-pass filtering ?

Stephen Politzer-Ahles spa268 at nyu.edu
Sat Dec 13 14:04:25 CET 2014


Hello Emmanuelle,

I don't think a high-pass filter can replace demeaning. A high-pass filter
removes a linear trend, but not a fixed value. Imagine a case where a trial
is a flat line at 100 uV for the whole epoch; demeaning would change this
trial to 0 uV for the whole epoch, whereas a high-pass filter would (I
think) not change it.

Detrending, on the other hand, removes a linear trend. There was a
discussion very recently on this list discussing detrending vs. high-pass
filtering, so you may be interested in checking it out.

Best,
Steve



Stephen Politzer-Ahles
New York University, Abu Dhabi
Neuroscience of Language Lab
http://www.nyu.edu/projects/politzer-ahles/



>
> Message: 1
> Date: Fri, 12 Dec 2014 15:49:10 +0100
> From: Kristensen Emmanuelle
>         <emmanuelle.kristensen at gipsa-lab.grenoble-inp.fr>
> To: FieldTrip discussion list <fieldtrip at science.ru.nl>
> Subject: [FieldTrip] Correction baseline : removing the mean value or
>         high-pass filtering ?
> Message-ID: <548B0066.3090309 at gipsa-lab.grenoble-inp.fr>
> Content-Type: text/plain; charset="utf-8"; Format="flowed"
>
> Hi,
> I would need your opinion, please.
> Generally, the baseline correction means to remove a mean value from
> each epoch. I am wondering if a high pass filter, applied on the whole
> recorded signal, can perform the baseline correction.
> What do you think?
> Regards
> Emmanuelle
>
> --
> Emmanuelle KRISTENSEN
> Doctorante au Gipsa-Lab
> Equipe VIBS
>
>
>
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