[FieldTrip] How do you prevent ft_resample from filtering your trigger channels?
jan-mathijs schoffelen
jan.schoffelen at donders.ru.nl
Fri Jun 13 13:33:54 CEST 2014
Hi Aaron,
You can use cfg.method = ‘nearest’ when downsampling the trigger channels. I suspect that in this case no filtering will be applied.
Thus, call ft_resampledata twice (each time with a different method: once for the functional data, the other time for the trigger(s)), and call ft_appenddata afterwards.
Best,
Jan-Mathijs
On Jun 13, 2014, at 1:08 PM, Aaron Schurger <aaron.schurger at gmail.com> wrote:
> Hi,
> It seems that ft_resample applies to all of the channels in the data
> structure. During resampling fieldtrip applies a filter, which adds
> artifacts to the step function in the trigger channels. For
> downsampling at least it would be great if you could specify a subset
> of channels to be downsampled by simple decimation (i.e. skip the
> lowpass filter). Is there any built-in way to do this?
> Thanks!
> Aaron
>
> --
> Aaron Schurger, PhD
> Senior researcher
> Laboratory of Cognitive Neuroscience
> Brain-Mind Institute, Department of Life Sciences
> École Polytechnique Fédérale de Lausanne
> Station 19, AI 2101
> 1015 Lausanne, Switzerland
> +41 21 693 1771
> aaron.schurger at epfl.ch
> http://lnco.epfl.ch/
>
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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
Max Planck Institute for Psycholinguistics,
Nijmegen, The Netherlands
J.Schoffelen at donders.ru.nl
Telephone: +31-24-3614793
http://www.hettaligebrein.nl
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