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

Alibou Nabil William Jean-Pierre nabil.alibou at epfl.ch
Sat Aug 31 04:05:12 PDT 2019



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) :
https://imgur.com/ptEEpPD

[https://i.imgur.com/ptEEpPD.png?fb]<https://imgur.com/ptEEpPD>

Imgur: The magic of the Internet<https://imgur.com/ptEEpPD>
imgur.com
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<https://i.imgur.com/ptEEpPD.png>https://imgur.com/yVgDg2k

[https://i.imgur.com/yVgDg2k.png?fb]<https://imgur.com/yVgDg2k>

Imgur: The magic of the Internet<https://imgur.com/yVgDg2k>
imgur.com
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https://imgur.com/PLLqEMz
[https://i.imgur.com/PLLqEMz.png?fb]<https://imgur.com/PLLqEMz>

Imgur: The magic of the Internet<https://imgur.com/PLLqEMz>
imgur.com
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https://imgur.com/rUl0q8K
[https://i.imgur.com/rUl0q8K.png?fb]<https://imgur.com/rUl0q8K>

Imgur: The magic of the Internet<https://imgur.com/rUl0q8K>
imgur.com
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https://imgur.com/ftds9nY
[https://i.imgur.com/ftds9nY.png?fb]<https://imgur.com/ftds9nY>

Imgur: The magic of the Internet<https://imgur.com/ftds9nY>
imgur.com
Post with 0 votes and 2 views.




=> 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 :

figure();
        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.



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