[Eeglablist] Can i filtering in two different moments?

[Andreas Widmann]

Hello Tiago,

filtering of epoched data is actually not recommended. You will introduce edge effects. From your code example I do not yet understand why you would want to do that. Could you please explain the intention behind you approach?

Please note that pop_eegfilt is broken and deprecated and was replaced by pop_eegfiltnew (see http://journal.frontiersin.org/article/10.3389/fpsyg.2012.00233/full for details).

Best,
Andreas

> Am 28.11.2016 um 17:04 schrieb tiago lopes <tiago.lopes56 at yahoo.com>:
> 
> Hello Dears,
> I am developing an experiment where i try to evaluate the thalamocortical dysrhytimia in individuals with chronic pain.
> In order to improve the quality of the collected signal eeg by the removal of artifacts, i am filtring in two different moments:
> A) Before dividing into epochs
> B After being divided into epochs  
> 
> My question is: Can filtering at two different times compromise the reliability of the collected signal? (ie, in addition to the artifact, am i taking out brain information that compromises the interpretation of the data?)
> 
> Below is the script used in data processing.
> Thanks a lot for the help.
> 
> path ='C:\Users\Tiago Lopes\Documents\MATLAB\Script\REPOUSO E IMG\01 Set epochs e ICA (REPOUSO)\';
> epochs ='C:\Users\Tiago Lopes\Documents\MATLAB\Script\REPOUSO E IMG\TABELA DE EVENTOS 5000ms.txt';
> name=strcat(path,'*.ASC');
> d=dir(name);
> 
> for j=1:length(d)
>     filename = d(j).name;
>     EEG = pop_loadbci( filename, 600 );
>     EEG = pop_select( EEG,'nochannel',{'FOTO'});
>     EEG = pop_select( EEG,'nochannel',{'EMGd' 'EMGm'});
>     EEG = pop_chanedit(EEG, 'lookup','standard-10-5-cap385.elp');
>     EEG = pop_reref( EEG, [] );
>     EEG = pop_eegfilt( EEG, 0.5, 30, [], [0], 0, 0, 'fir1', 0);
>     EEG = pop_importevent( EEG, 'event',epochs,'fields',{'type' 'latency'},'skipline',1,'timeunit',0.001);
>     EEG = pop_epoch( EEG, {  }, [-.420 4.580], 'epochinfo', 'yes');
>     EEG = pop_rmbase(EEG,[-300 0]);
>     EEG = pop_eegfilt( EEG, 1.80, 30, [], [0], 0, 0, 'fir1', 0);
>     EEG = pop_epoch( EEG, {  }, [-.420 4.580], 'epochinfo', 'yes');
>     EEG = pop_rmbase(EEG,[-300 0]);
>     EEG = pop_runica(EEG, 'extended',1,'interupt','on');
>     EEG = pop_subcomp( EEG, [1 2], 0);
>     EEG = pop_saveset( EEG, 'filename',d(j).name,'filepath',path);
> end
> 
> Att. Tiago Lopes
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