[Eeglablist] How to filter only EOG Channels?

[Andreas Widmann]

Hi Hanna,

I do not think this is possible from the GUI in a straight-forward way. Probably easiest is to copy the filtered channels from the filtered dataset to the unfiltered dataset on the command line:

(1) Filter dataset 1 creating a new filtered dataset 2
(2) Select unfiltered dataset 1 in the GUI (Datasets -> Dataset 1)
(3) Copy the relevant channels from the filtered to the unfiltered dataset on the command line and update the ALLEEG structure:
>> EEG.data(31:32, :) = ALLEEG(2).data(31:32, :);
>> [ALLEEG EEG CURRENTSET] = eeg_store(ALLEEG, EEG, CURRENTSET);

Note: this is just an example and you have to adjust channel and dataset indices.

You can make step (1) computationally more efficient by first selecting only the relevant to be filtered channels in the GUI (Edit -> select data) or command line: e.g.
>> EEG = pop_select( EEG,'channel',{'Fp1' 'F7'});
before filtering. However, you then have to be careful with the channel indices when copying the data: for example
>> EEG.data(31:32, :) = ALLEEG(3).data(1:2, :);
>> [ALLEEG EEG CURRENTSET] = eeg_store(ALLEEG, EEG, CURRENTSET);

Hope this helps,
Andreas

> Am 17.10.2016 um 14:02 schrieb Hanna Kadel <kadel at staff.uni-marburg.de>:
> 
> Dear EEGLab users, dear developers,
> 
> I would like to use a low-pass filter on selected channels of my EEG
> data structure.  So far, I've used pop_eegfiltnew for data filtering,
> but this applies the filter to all channels in the dataset. Is there any
> possibility to apply a filter *only* to specified channels, leaving all
> the other data unchanged? Or would I need to define my own filter
> function for this purpose, or use some workaround with copying parts of
> the dataset back and forth?
> 
> (Background: For rejection of eye-movement-contaminated trials, I use
> VEOG and HEOG difference channels. Due to high frequency noise artifacts
> in some recordings, I get a lot of "false positive" artifact trials.
> Thus, I would like to low-pass filter the EOG-difference channels prior
> to artifact detection)
> 
> Thanks a lot in advance for any hints & advice.
> 
> Hanna
> 
> -- 
> Dipl.-Psych. Hanna Kadel
> Philipps-Universität Marburg
> Fachbereich Psychologie
> Cognitive Neuroscience of Perception and Action
> Gutenbergstraße 18
> D-35032 Marburg
> 
> Tel: 06421 28-22160
> E-Mail: hanna.kadel at staff.uni-marburg.de
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