Preprocessing notes

Import data

Biosemi Active II data are recorded reference-free, but LOSE 40 dB of SNR if no reference is used!. If you do not know which channel to use, pick one and then re-reference afterthe channel locations are read in.

EEG EEG = pop_biosig(fullfile(path{n},file{n}),'ref',48); 
EEG = eeg_checkset( EEG );
EEG=pop_chanedit(EEG, 'lookup','W:\64 EEG\EEG_PROJECTS\eMID preprocessing test\64_6_RW.ced');
EEG = eeg_checkset( EEG );
EEG = pop_reref( EEG, [69 70] );
EEG = pop_select( EEG,'nochannel',{'EXG7' 'EXG8'});
EEG = eeg_checkset( EEG );

However, I compared importation with and without specifying ref, the results looked the same.

Filter

EEG = pop_eegfiltnew(EEG, 0.1,15,16896,0,[],1); %check parameters with EEGlab
EEG = eeg_checkset( EEG );

High pass filter problem (Not higher than 0.1 Hz)

In several applications such as event-related potential (ERP) and event-related field (ERF) analysis, high-pass filters with cutoff frequencies greater than 0.1 Hz are usually considered problematic since they significantly change the shape of the resulting averaged waveform. In such applications, apply high-pass filters with caution. For example:

Tanner D, Morgan-Short K, Luck SJ. How inappropriate high-pass filters can produce artifactual effects and incorrect conclusions in ERP studies of language and cognition.Psychophysiology. 2015;52(8):997-1009. doi:10.1111/psyp.12437.

It worths noting that low pass filter is also controversy in fMRI time course extraction. Link

ICA