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Artifact processing and ERP analysis

Artifact processing and ERP analysis. Task 1 Reject bad channels Task 2 Reject continuous data Task 3 Reject data epochs Task 4 Analysis of channel ERPs Exercise. The example data: faces vs. objects. File ../data/faces_3.set Data

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Artifact processing and ERP analysis

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  1. Artifact processing and ERP analysis Task 1 Reject bad channels Task 2 Reject continuous data Task 3 Reject data epochs Task 4 Analysis of channel ERPs Exercise... EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  2. The example data: faces vs. objects • File • ../data/faces_3.set • Data • 33 channel EEG, nose-tip reference, 250 Hz sampling rate, 0.5-100 Hz, 16 bit, BrainAmps • Task • speeded discrimination between objects and faces, 500 ms presentation duration, ISI 500-1900 ms, 362 trials EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  3. Artifact processing and ERP analysis Task 1 Reject bad channels Task 2 Reject continuous data Task 3 Reject data epochs Task 4 Analysis of channel ERPs Exercise... EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  4. Reject bad channels >> EEG = pop_loadset('faces_3.set', '...\data\'); >> [ALLEEG EEG CURRENTSET] = eeg_store(ALLEEG, EEG, 0); EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  5. Reject bad channels >> pop_eegplot(EEG, 1, 1, 1); EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  6. Reject bad channels EEG = pop_select(EEG, 'nochannel', [19 24]); EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  7. Reject bad channels EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  8. Artifact processing and ERP analysis Task 1 Reject bad channels Task 2 Reject continuous data Task 3 Reject data epochs Task 4 Analysis of channel ERPs Exercise... EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  9. Reject continuous data Equivalent!! EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  10. Reject continuous data TIP: use ICA for eye blink correction EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  11. Reject continuous data strange Eye blink To prepare data for ICA, reject odd artifacts and keep stereotyped artifacts EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  12. Artifact processing and ERP analysis Task 1 Reject bad channels Task 2 Reject continuous data Task 3 Reject data epochs Task 4 Analysis of channel ERPs Exercise... EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  13. Extract Epochs (review) EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  14. Extract Epochs (review) >> EEG = pop_epoch(EEG,{'face' 'object'},[-1 2],... 'newname','faces_3_chans removed epochs',... 'epochinfo','yes'); >> [ALLEEG EEG CURRENTSET] = pop_newset(ALLEEG,EEG,... CURRENTSET,'setname',' 'faces_3_chans removed epochs '); EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  15. Reject data epochs EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  16. Reject data epochs visual inspection probability EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  17. Reject data epochs Probability (± 5 stds) Visual inspection EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  18. Reject data epochs EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  19. Reject data epochs EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  20. Reject data epochs >> EEG = pop_jointprob(EEG,1,[1:31],5,5,0,0); >> EEG = pop_rejepoch(EEG,find(EEG.reject.rejglobal),0); EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  21. Artifact processing and ERP analysis Task 1 Reject bad channels Task 2 Reject continuous data Task 3 Reject data epochs Task 4 Analysis of channel ERPs Exercise... EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  22. Analysis of ERPs Create separate data sets for face and object trials >> EEG=pop_selectevent(EEG,'type',{'face'},'deleteevents', ... 'off','deleteepochs','on'); >> [ALLEEG EEG CURRENTSET]=pop_newset(ALLEEG,EEG,4,... 'setname','faces only epochs'); EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  23. Analysis of ERPs Select only 'face' epochs: create a new dataset EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  24. Analysis of ERPs Do the same thing for 'object' epochs >> [EEG,ALLEEG,CURRENTSET]=pop_newset(ALLEEG,EEG,4, ... 'retrieve',3,'study',0); >> EEG=pop_selectevent(EEG,'type',{'object'},'deleteevents', ... 'off','deleteepochs','on'); >> [ALLEEG EEG CURRENTSET]=pop_newset(ALLEEG,EEG,5, ... 'setname','object only epochs'); EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  25. Analysis of ERPs >> pop_timtopo(EEG,[-200 796],[165],'ERP data and scalp maps'); EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  26. Analysis of ERPs EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  27. Analysis of ERPs >>pop_topoplot(EEG,1,[0:25:200],'face',[3 3],0,'electrodes','off'); EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  28. Analysis of ERPs >>pop_headplot(EEG,1,[0:25:200],'ERP scalp maps',[3 3],... 'electrodes', 'off'); EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  29. Analysis of ERPs 4 5 >>pop_comperp(ALLEEG,1,[4 5],[],'addavg','off','addstd','off',... 'addall','on','diffavg','off','diffstd','off','lowpass',20,... 'tplotopt',{'ydir',-1}); EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  30. Analysis of ERPs 4 5 ERP difference between 2 conditions EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  31. Analysis of ERPs >> pop_export(EEG,'D:\tmp\faces.dat','erp','on',... 'transpose','on','time','off'); EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

  32. Exercise • Load dataset 'faces_3.set' from '…/data/' directory • Reject noisy channels • (optional: reject continuous data stretches) • Epoch dataset on all 'face' and 'object' events • Explore 1 or more of the following: • Reject noisy epochs by hand or use auto-rejection • Compare rejection methods and thresholds • Select 'face' and 'object' epochs separately • Plot ERPs • superimposed ERP envelopes • rectangular/scalp array • Compare 'face' vs 'object' ERPs • Export 'face' ERPs into an ascii file EEGLAB Workshop III, Nov. 15-18, 2005, Singapore: Julie Onton – Artifact processing and ERP analysis

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