<html><body><div style="font-family: arial, helvetica, sans-serif; font-size: 12pt; color: #000000"><div>Hi Robert,</div><div><br data-mce-bogus="1"></div><div>in your preprocessing, did you use: </div><div>cfg.demean = 'yes';</div><div><br data-mce-bogus="1"></div><div>If no then I suggest you take a look at this link:</div><div>http://www.fieldtriptoolbox.org/faq/why_does_my_tfr_look_strange</div><div><br data-mce-bogus="1"></div><div>The stripe pattern could result from the DC-offset which gets removed when doing demeaning with the cfg-option.</div><div>Try something like this before feeding data into ft_freqanalysis.</div><div><br data-mce-bogus="1"></div><div>cfg = [];</div><div>cfg.detrending = 'yes';</div><div>cfg.demean = 'yes';</div><div>[data] = ft_preprocessing(cfg,data);</div><div><br data-mce-bogus="1"></div><div>Then use data with ft_freqanalysis.<br data-mce-bogus="1"></div><div><br data-mce-bogus="1"></div><div>HTH</div><div>Fred<br><br></div><div data-marker="__SIG_PRE__">--<br>FR<br><br>Legal disclaimer/Aviso legal/Lege-oharra: www.bcbl.eu/legal-disclaimer<br>---------------------------------------------------------------------------</div><div><br></div><hr id="zwchr" data-marker="__DIVIDER__"><div data-marker="__HEADERS__"><b>From: </b>"Seymour, Robert (Research Student)" <seymourr@aston.ac.uk><br><b>To: </b>"fieldtrip_mailinglist" <fieldtrip@science.ru.nl><br><b>Sent: </b>Monday, February 22, 2016 7:49:25 PM<br><b>Subject: </b>[FieldTrip] Maxfilter SSS and TF-Plots<br></div><div><br></div><div data-marker="__QUOTED_TEXT__"><style style="display:none;"><!-- P {margin-top:0;margin-bottom:0;} --></style>
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<p>Dear all,</p>
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<p>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 : <a href="http://i.imgur.com/QGma6qm.png" id="LPlnk649004" title="http://i.imgur.com/QGma6qm.png
Ctrl+Click or tap to follow the link" target="_blank">http://i.imgur.com/QGma6qm.png</a>.
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?</p>
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<p>Many thanks, </p>
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<p>Robert Seymour (Aston Brain Centre)</p>
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