<div dir="ltr"><div dir="ltr"><div dir="ltr"><div dir="ltr"><div>Dear Silvia,</div><div><br></div><div>how is the electrode location information from the BioSemi website not enough?</div><div>Basically, you can create your own electrode definition by giving the labels and locations to a structure, e.g. <br></div>elec.label{1} = 'Fp1';<br>elec.chanpos(1,:) = [-27.0333934563814, 83.2002299946862, -3.05493522574547];</div><div dir="ltr"><br></div><div>or for all your electrodes in one go:</div><div>elec.label = {'Fp1','AF7','AF3','F1','F5'};<br>elec.chanpos = [-27.0333934563814, 83.2002299946862, -3.05493522574547;...<br>-51.4205700085246, 70.7743429000555, -3.05493522574547;...<br>-35.5608995849164, 76.2605952593987, 24.1279774030766;...<br>-25.1195714566887, 62.1731210759014, 56.2665567427342;...<br>-47.7073482911603, 58.9136687505812, 43.7676114900325];</div><div><br></div><div>plot3(elec.chanpos(:,1),elec.chanpos(:,2),elec.chanpos(:,3),'*')</div><div><br></div><div>or of course read them more elegantly from a text file ;-)<br></div><div><br></div><div>It might be a good idea to double check the alignment with the template headmodel afterwards using ft_electroderealign<br></div><div>You can then use this elec structure in all subsequent analyses.</div><div><br></div><div>I hope that helps,</div><div><br></div><div>Julian<br></div></div></div></div><br><div class="gmail_quote"><div dir="ltr">On Thu, Jan 10, 2019 at 10:59 AM Silvia Formica <<a href="mailto:Silvia.Formica@ugent.be" target="_blank">Silvia.Formica@ugent.be</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
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<p>Dear all,<br>
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<p>I have a EEG dataset, collected with a Biosemi system with 64 channels. I don't have the individual anatomical data for each participant, but I want to perform source reconstruction to have at least a rough localization of the activation I find.<br>
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<p>Therefore, I intend to use the templates provided by fieldtrip. If I understand correctly, independently of the source modelling technique that I will choose to use, I need the following information:<br>
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<p style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:16px">1) the <strong>head model</strong> : this would be the template '<em>standard_bem'</em><br>
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<p style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:16px"><br>
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<p style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:16px">2) the <strong>source model</strong> : the template '<em>cortex_5124.surf.gii</em>'<br>
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<p style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:16px">3) the <strong>elec information</strong> : this file should describe the spatial configuration of the electrodes, but I can't retrieve it. I don't think any of the templates available
fits my data (they all have more than 64 channels and different configurations). </p>
<p style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:16px"><br>
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<p style="font-family:Calibri,Arial,Helvetica,sans-serif;font-size:16px">I tried to use the function ft_read_sens on my data but I get the following error<br>
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<p><span style="font-size:12pt">elec = ft_read_sens([</span><span style="font-size:12pt">data_filt5.mat'],'senstype','eeg');</span></p>
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<div><span style="color:rgb(255,0,0);text-decoration:none rgb(255,0,0)">Undefined function or variable 'lab'.</span></div>
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<div><span style="color:rgb(255,0,0);text-decoration:none rgb(255,0,0)">Error in channelposition (line 316)</span></div>
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<div><span style="color:rgb(255,0,0);text-decoration:none rgb(255,0,0)">n = size(lab,2);</span></div>
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<div><br style="color:rgb(255,0,0);text-decoration:none rgb(255,0,0)">
</div>
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<div><span style="color:rgb(255,0,0);text-decoration:none rgb(255,0,0)">Error in ft_datatype_sens (line 349)</span></div>
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<div><span style="color:rgb(255,0,0);text-decoration:none rgb(255,0,0)"> [chanpos, chanori, lab] = channelposition(sens);</span></div>
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<div><span style="color:rgb(255,0,0);text-decoration:none rgb(255,0,0)">Error in ft_datatype_sens (line 158)</span></div>
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<div><span style="color:rgb(255,0,0);text-decoration:none rgb(255,0,0)"> sens = ft_datatype_sens(sens, 'version', '2011v2');</span></div>
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<div><br style="color:rgb(255,0,0);text-decoration:none rgb(255,0,0)">
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<div><span style="color:rgb(255,0,0);text-decoration:none rgb(255,0,0)">Error in ft_read_sens (line 380)</span></div>
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<div><span style="color:rgb(255,0,0);text-decoration:none rgb(255,0,0)">sens = ft_datatype_sens(sens);</span><br>
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<p>I found the cartesian coordinates of the electrodes on the Biosemi website, with the x y z coordinates for each electrodes (as the little example I'm giving below, but that's not enough. <br>
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<span style="font-size:12pt">Channel x</span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt">y</span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt"> </span><span style="font-size:12pt">
z</span><br>
<span style="font-size:12pt">Fp1 -27.0333934563814</span><span style="font-size:12pt;white-space:pre-wrap">
</span><span style="font-size:12pt">83.2002299946862</span><span style="font-size:12pt;white-space:pre-wrap">
</span><span style="font-size:12pt">-3.05493522574547</span><br>
<span style="font-size:12pt">AF7 -51.4205700085246</span><span style="font-size:12pt;white-space:pre-wrap">
</span><span style="font-size:12pt">70.7743429000555</span><span style="font-size:12pt;white-space:pre-wrap">
</span><span style="font-size:12pt">-3.05493522574547</span><br>
<span style="font-size:12pt">AF3 -35.5608995849164</span><span style="font-size:12pt;white-space:pre-wrap">
</span><span style="font-size:12pt">76.2605952593987</span><span style="font-size:12pt;white-space:pre-wrap">
</span><span style="font-size:12pt">24.1279774030766</span><br>
<span style="font-size:12pt">F1 -25.1195714566887</span><span style="font-size:12pt;white-space:pre-wrap">
</span><span style="font-size:12pt">62.1731210759014</span><span style="font-size:12pt;white-space:pre-wrap">
</span><span style="font-size:12pt">56.2665567427342</span><br>
<span style="font-size:12pt">F5 -47.7073482911603</span><span style="font-size:12pt;white-space:pre-wrap">
</span><span style="font-size:12pt">58.9136687505812</span><span style="font-size:12pt;white-space:pre-wrap">
</span><span style="font-size:12pt">43.7676114900325</span><br>
<p>... ... ... ...</p>
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<p><strong>Do you have any suggestions on how to create a correct elec file fitting my data?</strong><br>
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<p>Any help would be highly appreciated!<br>
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<p>Silvia<br>
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