[Eeglablist] ICA: include linked mastoids?

[Clemens DICKHUT]

Dear all,

I am using a 64 channel acticap, online reference FCz. To recover FCz I append a 65th channel and rereference to the average. Then, I rereference to linked mastoids (TP9, TP10).
When running an ICA now, I try to include all 65 channels and a window popped up saying the rank computation may be inaccurate (?). I changed the channel number from 64 to 65 and ran the analyses.  All the resulting components where the same (kind of mastoid topgraphy). I am therefore asking which electrodes I have to include for the ICA... Perhaps not the two mastoids, thus 63 channels for the ICA?

I am including my code for the rereferencing here

% Get channel locations, append FCz, set as reference
EEG = pop_chanedit(EEG, 'lookup','C:\\Program Files\\MATLAB\\eeglab13_5_4b\\plugins\\dipfit2.3\\standard_BESA\\standard-10-5-cap385.elp','append',64,'changefield',{65 'labels' 'FCz'},'lookup','C:\\Program Files\\MATLAB\\eeglab13_5_4b\\plugins\\dipfit2.3\\standard_BESA\\standard-10-5-cap385.elp','setref',{'1:65' 'FCz'});
[ALLEEG EEG] = eeg_store(ALLEEG, EEG, CURRENTSET);
EEG = pop_chanedit(EEG, 'setref',{'1:65' 'FCz'});

% Average reference
EEG = pop_reref( EEG, [],'refloc',struct('labels',{'FCz'},'type',{''},'theta',{0},'radius',{0.12662},'X',{32.9279},'Y',{0},'Z',{78.363},'sph_theta',{0},'sph_phi',{67.208},'sph_radius',{85},'urchan',{65},'ref',{'FCz'},'datachan',{0}));
[ALLEEG EEG CURRENTSET] = pop_newset(ALLEEG, EEG, 1,'setname','average_ref','overwrite','on','gui','off');
EEG = eeg_checkset( EEG );
% Re-reference to linked mastoids (TP9 TP10) and retain the two channels
EEG = pop_reref( EEG, [17 22] ,'keepref','on');
[ALLEEG EEG CURRENTSET] = pop_newset(ALLEEG, EEG, 1,'setname','ref_linked_mastoids','overwrite','on','gui','off');
[ALLEEG EEG] = eeg_store(ALLEEG, EEG, CURRENTSET);


I am looking forward to your ideas.

Best,
Clemens

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