<div dir="ltr"><div class="gmail_default">Dear Simon</div><div class="gmail_default"><br></div><div class="gmail_default">Thanks a lot for your attention and sorry for the late response. I've actually found which part of the code makes a problem. I used the ft_prepare_vol_sens's function in a wrong way. </div><div class="gmail_default" style="font-size:large"><span style="font-size:small"><br></span></div><div class="gmail_default" style="font-size:large"><span style="font-size:small">Now I have another problem. </span><span style="font-size:12.8px">I change the coordination system from 'ctf' to 'spm' by using this code:</span></div><div class="gmail_default" style="font-size:12.8px"><p class="m_1105658089966123248gmail-m_3497945127204109288gmail-p1">cfg = [];</p><p class="m_1105658089966123248gmail-m_3497945127204109288gmail-p1">[mri] = ft_volumenormalise(cfg, mri);</p><p class="m_1105658089966123248gmail-m_3497945127204109288gmail-p1">When I segmented 'scalp' separately and prepared mesh from it, the figure was well (1.fig). On the other hand when I changed the segmentation into {'brain', 'skull', 'scalp'}, the scalp can not be computed properly (2.fig). </p></div>
</div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Oct 3, 2016 at 4:57 PM, Simon Homolle <span dir="ltr"><<a href="mailto:s.homolle@donders.ru.nl" target="_blank">s.homolle@donders.ru.nl</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word">Dear Pooneh,<div><br></div><div><a href="http://www.fieldtriptoolbox.org/tutorial/headmodel_eeg_bem" target="_blank">http://www.fieldtriptoolbox.<wbr>org/tutorial/headmodel_eeg_bem</a></div><div><br></div><div>I relate to this part:</div><blockquote style="margin:0 0 0 40px;border:none;padding:0px"><div><br></div><div><span style="text-align:justify;background-color:rgb(255,255,255)"> When the forward solution is computed, the </span><span style="padding:0px;margin:0px;text-align:justify">lead field matrix</span><span style="text-align:justify;background-color:rgb(255,255,255)"> (= channels X source points matrix) is calculated <b>for each grid point</b> taking into account the head model and the channel positions.</span></div></blockquote><div><br></div><div>So I assume your mesh consists of 2000 grid points?</div><div><span class=""><br><div>
Simon Homölle<br>PhD Candidate<br>Donders Institute for Brain, Cognition and Behaviour<br>Centre for Cognitive Neuroimaging<br>Radboud University Nijmegen<br>Phone: +31-(0)24-36-65059
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<br></span><div><div class="h5"><div><blockquote type="cite"><div>On 03 Oct 2016, at 13:01, pooneh baniasad <<a href="mailto:pooneh.baniasad@gmail.com" target="_blank">pooneh.baniasad@gmail.com</a>> wrote:</div><br class="m_-6196312192892129590Apple-interchange-newline"><div><div dir="ltr"><div class="gmail_default">Dear Simon,</div><div class="gmail_default"><br></div><div class="gmail_default">I've followed this tutorial:</div><div class="gmail_default"><a href="http://www.fieldtriptoolbox.org/tutorial/headmodel_eeg_bem" target="_blank">http://www.fieldtriptoolbox.<wbr>org/tutorial/headmodel_eeg_bem</a> to construct the headmodel ('VolBEM') <br></div><div class="gmail_default">I use 'standard_1020.elc' for 'elec' and 'cortex_20484.surf.gii' for 'DipPos'.</div><div class="gmail_default">Is it clear or should I explain more?<font size="1"> 🙂</font></div>
</div><div class="gmail_extra"><br><div class="gmail_quote">On Mon, Oct 3, 2016 at 11:53 AM, Simon Homolle <span dir="ltr"><<a href="mailto:s.homolle@donders.ru.nl" target="_blank">s.homolle@donders.ru.nl</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word">Dear pooh,<div><br></div><div>Could you provide more information how you constructed your BEM-model?</div><div><br></div><div>best regards,</div><div><br><div>
Simon Homölle<br>PhD Candidate<br>Donders Institute for Brain, Cognition and Behaviour<br>Centre for Cognitive Neuroimaging<br>Radboud University Nijmegen<br>Phone: +31-(0)24-36-65059
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<br><div><blockquote type="cite"><div><div class="m_-6196312192892129590h5"><div>On 02 Oct 2016, at 12:22, pooneh baniasad <<a href="mailto:pooneh.baniasad@gmail.com" target="_blank">pooneh.baniasad@gmail.com</a>> wrote:</div><br class="m_-6196312192892129590m_-6321561874137257934Apple-interchange-newline"></div></div><div><div><div class="m_-6196312192892129590h5"><div dir="ltr"><div class="gmail_default" style="font-size:large"><span style="font-size:12.8px">Dear FieldTrip community</span><br clear="all"></div><div class="gmail_default" style="font-size:large"><span style="font-size:12.8px"><br></span></div><div class="gmail_default"><div class="gmail_default" style="font-size:12.8px">I'm using the forward model to simulating EEG signal although it seems the dimension of the lead-field matrix is not correct. Here is a review of the procedure.</div><div class="gmail_default" style="font-size:12.8px"><br></div><div class="gmail_default" style="font-size:12.8px">First I constructed a BEM headmodel for EEG source analysis and then by loading the template cortex, I put the dipoles with specific current source on that. I expect the dimension of the lead-field matrix will be m*n which m=electrode's number and n=3*dipole's number but 'm' is different. </div><div class="gmail_default" style="font-size:12.8px">Since I used the template electrode 'standard_1020.elc', m = 97 according to:</div><div class="gmail_default" style="font-size:12.8px"> <br></div><div class="gmail_default" style="font-size:12.8px"><div class="gmail_default" style="font-size:12.8px"> chanpos: [97x3 double]</div><div class="gmail_default" style="font-size:12.8px"> chantype: {97x1 cell}</div><div class="gmail_default" style="font-size:12.8px"> chanunit: {97x1 cell}</div><div class="gmail_default" style="font-size:12.8px"> elecpos: [97x3 double]</div><div class="gmail_default" style="font-size:12.8px"> label: {97x1 cell}</div><div class="gmail_default" style="font-size:12.8px"> type: 'eeg1010'</div><div class="gmail_default" style="font-size:12.8px"> unit: 'mm'</div><div><br></div></div><div>while the dimension of lead-field matrix is:
2000x122880 </div><div><p class="m_-6196312192892129590m_-6321561874137257934gmail-p1">I use this function for calculating lead-field matrix:</p><p class="m_-6196312192892129590m_-6321561874137257934gmail-p1">LF = ft_compute_leadfield(DipPos, elec, VolBEM);</p></div></div><div><div class="gmail_default">I do not understand why the number of raws are different!</div><div class="gmail_default"><br></div><div class="gmail_default">On the other hand I guess that there is a similarity between the number of raws in the volume head model and LF matrix due to the dimension of headmodel matrix is: 2000x8000 double .</div><br></div><div><div class="gmail_default">I will be so thankful if anyone can help me.</div><br></div>-- <br><div class="m_-6196312192892129590m_-6321561874137257934gmail-m_7370803151998605674gmail_signature"><div dir="ltr">Bests<div><br></div><div>Pouneh Baniasad</div></div></div>
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