[Eeglablist] ERSP : activity systematically shifted at t=0

Johnson, John T. john.johnson at gatech.edu
Mon Sep 2 04:49:51 PDT 2019

I don’t know your experiment, but the regularity of that component's signal makes me think it is an artifact. Since it occurs every second, perhaps it is an ecg artifact from the heart (?). Have you watched any of Mike X. Cohen's videos or read his material online or his books? They’ve been very helpful to me. http://mikexcohen.com/


John T. Johnson
PhD Candidate - Cognitive Motor Control Lab
School of Biological Sciences
Georgia Institute of Technology

john.johnson at gatech.edu

On Sep 2, 2019, at 7:21 AM, Alibou Nabil William Jean-Pierre <nabil.alibou at epfl.ch> wrote:

I am starting in the eeg analysis field and i was studying the TF analysis of my dataset with newtimef()

but i noticed that the activity, regardless of the event, was always at t = 0s (and for every subject).

Exemple of ERP/ERSP of components from my dataset (with extended epoch) :



=> However if i test it with a constant signal with a spike at a certain time the spectral activity displayed will be at the corresponding t.
Im using this parameters :

       newtimef(EEG.icaact(5,:,:), EEG.pnts, [EEG.xmin EEG.xmax]*1000, EEG.srate,0,'freqscale','linear', ...
           'cycles',[5 0.5],'elocs', EEG.chanlocs, 'chaninfo', EEG.chaninfo,  ...
           'freqs',[5 50], 'maxfreq',50,'baseline',[EEG.xmin EEG.xmax]*1000,'trialbase', 'off','basenorm', 'off', 'plotitc', 'off', ... % divise into 2 portions of frequencies for study easily ?
           'caption','test', 'padratio', 4,'alpha',NaN,'ntimesout',100,'winsize',700, 'erspmax', 0.5);

I have changed almost every parameter but i still have this problem and i don't know the cause, thanks you in advance for your help.
Best regards,


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