[FieldTrip] Maxfilter SSS and TF-Plots

[Frédéric Roux]

Hi Robert, 

in your preprocessing, did you use: 
cfg.demean = 'yes'; 

If no then I suggest you take a look at this link: 
http://www.fieldtriptoolbox.org/faq/why_does_my_tfr_look_strange 

The stripe pattern could result from the DC-offset which gets removed when doing demeaning with the cfg-option. 
Try something like this before feeding data into ft_freqanalysis. 

cfg = []; 
cfg.detrending = 'yes'; 
cfg.demean = 'yes'; 
[data] = ft_preprocessing(cfg,data); 

Then use data with ft_freqanalysis. 

HTH 
Fred 

-- 
FR 

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From: "Seymour, Robert (Research Student)" <seymourr at aston.ac.uk> 
To: "fieldtrip_mailinglist" <fieldtrip at science.ru.nl> 
Sent: Monday, February 22, 2016 7:49:25 PM 
Subject: [FieldTrip] Maxfilter SSS and TF-Plots 



Dear all, 




I've been trying out various cleaning parameters on Neuromag data and importing this into Fieldtrip. I've found that applying SSS to my data results in time-frequency plots with bands of activity at very specific frequencies. Image : http://i.imgur.com/QGma6qm.png . I do not believe it is anything to do with plotting because the lines disappear when I use tSSS with a .9 correlation. Has anybody else experienced this or hypothesise as to the cause of these artefacts? 








Many thanks, 




Robert Seymour (Aston Brain Centre) 

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