[Eeglablist] Flat lines after epoching in one data set

Alexander Quent alexander.quent at rub.de
Wed Jun 10 12:01:38 PDT 2015


Dear eeglab users,
I have encounter a weird problem. I followed Makoto's pipeline for
pre-processing with a small deviation that I used linked mastoids rather
than average reference but I cannot imagine this causing my problem.
I pre-processed 27 data sets and all but one show satisfactory results
after pre-processing.
After following this pipeline, this data set is basically composed of
flat lines except for a few short periods with pikes. I tracked the
problem down to the function
pop_epoch. When checking the data visually before epoching, I do not
notice anything odd or peculiar, but after epoching all most everything
becomes flat.

Since I am a brute beginner, I indeed have no clue where the problem
might have hid. Have anybody encountered something similar?

With best regards
Alexander Quent


Appendix:
% for a = 4:length(population)
%         EEG         =
pop_fileio(strcat('C:\Users\Joern\Documents\MATLAB\Daten\BA\eeg\',
population{i},'.eeg')); % loads data file
%         if a < 12
%             EEG       = pop_loadset('filename',
strcat(population{a},'_Cut.set'),'filepath','C:\Users\Joern\Documents\MATLAB\Daten\BA\eeg\wholeData');

%         else
%             EEG       =
pop_fileio(strcat('C:\Users\Joern\Documents\MATLAB\Daten\BA\eeg\wholeData\',
population{a},'.eeg')); % loads data file
%         end
%         EEG.setname = strcat(population{a},'_Processed.eeg'); % names
dataset for continuous data
%         EEG         = eeg_checkset( EEG );
%         EEG         = pop_cleanline(EEG,
'bandwidth',2,'chanlist',[1:32] ,'computepower',1,'linefreqs',[50 100]
,'normSpectrum',0,'p',0.01,'pad',2,'plotfigures',0,'scanforlines',1,'sigtype','Channels','tau',100,'verb',1,'winsize',4,'winstep',1);

%         EEG         = eeg_checkset( EEG );
%         EEG         = pop_eegfiltnew(EEG, [], 1, 1650, true, [], 1);
%         EEG         = eeg_checkset( EEG );
%         EEG         = eeg_checkset( EEG );
%         EEG         = pop_editset( EEG, 'chanlocs',
'C:\\Users\\Joern\\Documents\\MATLAB\\eeglab_current\\eeglab13_4_4b\\sample_locs\\neuroscan_32_EOGincluded.ced');

%         EEG         = eeg_checkset( EEG );
%         EEG         = eeg_checkset( EEG );
%         EEG.data    = EEG.data - repmat(EEG.data(17, :) * 0.5,
[EEG.nbchan 1]); % Re reference to linked mastoid, see also
http://sccn.ucsd.edu/pipermail/eeglablist/2012/005585.html
%         EEG         = pop_select( EEG,'nochannel',{'REFlinks'});
%         EEG         = pop_rejchan(EEG, 'elec',[1:31]
,'threshold',5,'norm','on','measure','kurt');
%         EEG         = eeg_checkset( EEG );
%         EEG         = eeg_checkset( EEG );
%         EEG         = pop_epoch( EEG, {  'S 10'  'S 11'  'S 12'  'S
13'  'S 14'  'S 15'  }, [-1  2], 'newname',
strcat(population{a},'_Epochs', 'epochinfo', 'yes');
%         display('Exclude eye channels from joint')
%         if length(EEG.chanlocs) < 31
%             EEG     = pop_jointprob( EEG );
%         else
%             EEG     = pop_jointprob( EEG,1,[3:26 28 29:30] ,6,2,1,0);
%         end
%         EEG         = eeg_checkset( EEG );
%         EEG         = eeg_checkset( EEG );
%         EEG         = pop_runica(EEG, 'extended',1,'interupt','on');
%         EEG         = eeg_checkset( EEG );
%         [ALLEEG,EEG,CURRENTSET,com] = pop_ADJUST_interface
(ALLEEG,EEG,CURRENTSET );
%         EEG         = eeg_checkset( EEG );
%         stop        = input('Press 1 to continue: ');
%         EEG         = pop_subcomp( EEG );
%         EEG         = pop_eegfiltnew(EEG, [], 45, 148, 0, [], 1);
%         EEG         = pop_jointprob(EEG,1,[1:length(EEG.chanlocs)]
,3,3,1,0);
%         EEG         = eeg_checkset( EEG );
%         pop_eegplot( EEG, 1, 1, 1);
%         stop        = input('Press 1 to continue: ');
%         EEG         = eeg_checkset( EEG );
%         for j = 1:length(conditions)
%             EEG     =
addEventsBasedCorrectness(EEG,conditions{j},triggerNums(j), responses);
%             EEG     = eeg_checkset( EEG );
%         end
%         EEG         = pop_saveset(EEG, 'filename' ,
strcat(population{a},'_ProcessedERPEpochs'), 'filepath',
'C:\Users\Joern\Documents\MATLAB\Daten\BA\eeg\analyzedERPLAB'); % Saving
current data to file
%         EEG         = eeg_checkset( EEG );
% end


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