<div dir="ltr">Dear Fieldtrip community, <br>I am Carlota Pagès, a Ph.D. candidate in the CBC of UPF (Barcelona). Currently, I'm exploring the neural oscillations of music unexpectedness. <div><br clear="all"><div>I have run time-frequency analysis on my EEG data via wavelet convolution and applied a dB baseline correction for my different conditions. However, when I plot the output, it appears some activity that (in my opinion) does not look as brain-related because of its high power values and might be masking the effects of interest (best seen in electrode Fz). When I calculate the difference between conditions, it disappears. Therefore, it is equally present in all conditions.</div><div>I wondered whether it might be an artifact due to a preparation of blink (which happens right after the end of the trial) or an effect of the baseline correction (baselines are statistically equal across conditions). Please find the image and my script (for a single subject) below.</div><div>Have any of you observed something similar and have a clue on what could be causing it? And if so, what would be a good way to correct it? </div><div></div><div>Any help would be appreciated.</div><div><br></div><div>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier">cfg = [];</p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier">cfg.demean = <span class="gmail-s1" style="color:rgb(178,69,243)">'yes'</span>;</p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier">data_demean = ft_preprocessing(cfg, data);</p>
<p class="gmail-p2" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier;min-height:12px"><span class="gmail-Apple-converted-space">% wavelet convolution </span></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier">cfg = [];</p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier">cfg.method <span class="gmail-Apple-converted-space"> </span>= <span class="gmail-s1" style="color:rgb(178,69,243)">'wavelet'</span>;</p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier">cfg.output <span class="gmail-Apple-converted-space"> </span>= <span class="gmail-s1" style="color:rgb(178,69,243)">'pow'</span>;</p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier">cfg.foi<span class="gmail-Apple-converted-space"> </span>= 30:1:60;<span class="gmail-Apple-converted-space"> </span></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier">cfg.width<span class="gmail-Apple-converted-space"> </span>= 10;<span class="gmail-Apple-converted-space"> </span></p>
<p class="gmail-p3" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier;color:rgb(74,135,78)"><span class="gmail-s2" style="color:rgb(0,0,0)">cfg.toi<span class="gmail-Apple-converted-space"> </span>= -0.7:0.03:1.2; </span></p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier">cfg.pad =<span class="gmail-Apple-converted-space"> </span>2;</p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier">cfg.trials <span class="gmail-Apple-converted-space"> </span>= data.trialinfo == 1;</p>
<p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier">wavelet_cond1 = ft_freqanalysis(cfg, data_demean);</p><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier">% db normalization</p><p class="gmail-p1" style="margin:0px;font:10px Courier">cfg = [];</p><p class="gmail-p1" style="margin:0px;font:10px Courier">cfg.baseline = [-0.2 -0.05];</p><p class="gmail-p1" style="margin:0px;font:10px Courier">cfg.baselinetype = <span class="gmail-s1" style="color:rgb(178,69,243)">'db'</span>;</p><p class="gmail-p2" style="margin:0px;font:10px Courier;min-height:12px">wavelet_cond1_db = ft_freqbaseline(cfg, wavelet_cond1);</p><p class="gmail-p2" style="margin:0px;font:10px Courier;min-height:12px">% multiplot</p><p class="gmail-p1" style="margin:0px;font:10px Courier">cfg = [];</p><p class="gmail-p1" style="margin:0px;font:10px Courier">cfg.colorbar <span class="gmail-Apple-converted-space"> </span>= <span class="gmail-s1" style="color:rgb(178,69,243)">'yes'</span>;</p><p class="gmail-p1" style="margin:0px;font:10px Courier">cfg.channel = {<span class="gmail-s1" style="color:rgb(178,69,243)">'all'</span>, <span class="gmail-s1" style="color:rgb(178,69,243)">'-Fp1'</span>, <span class="gmail-s1" style="color:rgb(178,69,243)">'-Fp2'</span>};</p><p class="gmail-p1" style="margin:0px;font:10px Courier">cfg.showlabels = <span class="gmail-s1" style="color:rgb(178,69,243)">'yes'</span>;</p><p class="gmail-p1" style="margin:0px;font:10px Courier">cfg.layout = acticap32;</p><p class="gmail-p1" style="margin:0px;font:10px Courier">figure; ft_multiplotTFR(cfg, wavelet_cond1_db);</p><p class="gmail-p1" style="margin:0px;font:10px Courier"><br></p><img src="cid:ii_kioyynxh0" alt="multiplot.png" width="478" height="353"><br><p class="gmail-p1" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier"><br></p>
<p class="gmail-p2" style="margin:0px;font-variant-numeric:normal;font-variant-east-asian:normal;font-stretch:normal;font-size:10px;line-height:normal;font-family:Courier;min-height:12px"><span class="gmail-Apple-converted-space"> </span></p></div><div><br></div><div><br></div>-- <br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><font color="#000000">Carlota Pagès</font><div><br><div><a href="https://www.upf.edu/web/lcc/entry/-/-/139611/adscripcion/carlota-pag%C3%A8s" target="_blank">PhD Student </a></div><div><a href="https://www.upf.edu/web/lcc" target="_blank">Language & Comparative Cognition Group</a> l <span style="font-size:12.8px"><a href="http://cbc.upf.edu/" target="_blank">Center for Brain and Cognition</a> l </span><span style="font-size:12.8px">UPF </span></div><div><span style="font-size:12.8px"><br></span></div><div><div style="font-size:12.8px"><font face="verdana, sans-serif" color="#999999"><u>Office 24.326</u></font></div><div style="font-size:12.8px"><font face="verdana, sans-serif" color="#999999"><u>Mercè Rodoreda Building</u></font></div><div style="font-size:12.8px"><font face="verdana, sans-serif" color="#999999"><u><span title="Ramon Trias Fargas, 25-27
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