<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Dear Pooneh,<div class=""><br class=""></div><div class=""><a href="http://www.fieldtriptoolbox.org/tutorial/headmodel_eeg_bem" class="">http://www.fieldtriptoolbox.org/tutorial/headmodel_eeg_bem</a></div><div class=""><br class=""></div><div class="">I relate to this part:</div><blockquote style="margin: 0 0 0 40px; border: none; padding: 0px;" class=""><div class=""><br class=""></div><div class=""><span style="text-align: justify; background-color: rgb(255, 255, 255);" class=""> When the forward solution is computed, the </span><span style="padding: 0px; margin: 0px; text-align: justify;" class="">lead field matrix</span><span style="text-align: justify; background-color: rgb(255, 255, 255);" class=""> (= channels X source points matrix) is calculated <b class="">for each grid point</b> taking into account the head model and the channel positions.</span></div></blockquote><div class=""><br class=""></div><div class="">So I assume your mesh consists of 2000 grid points?</div><div class=""><br class=""><div class="">
Simon Homölle<br class="">PhD Candidate<br class="">Donders Institute for Brain, Cognition and Behaviour<br class="">Centre for Cognitive Neuroimaging<br class="">Radboud University Nijmegen<br class="">Phone: +31-(0)24-36-65059
</div>
<br class=""><div><blockquote type="cite" class=""><div class="">On 03 Oct 2016, at 13:01, pooneh baniasad <<a href="mailto:pooneh.baniasad@gmail.com" class="">pooneh.baniasad@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class=""><meta http-equiv="Content-Type" content="text/html; charset=utf-8" class=""><div dir="ltr" class=""><div class="gmail_default">Dear Simon,</div><div class="gmail_default"><br class=""></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" class="">http://www.fieldtriptoolbox.org/tutorial/headmodel_eeg_bem</a> to construct the headmodel ('VolBEM') <br class=""></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" class=""> 🙂</font></div>
</div><div class="gmail_extra"><br class=""><div class="gmail_quote">On Mon, Oct 3, 2016 at 11:53 AM, Simon Homolle <span dir="ltr" class=""><<a href="mailto:s.homolle@donders.ru.nl" target="_blank" class="">s.homolle@donders.ru.nl</a>></span> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div style="word-wrap:break-word" class="">Dear pooh,<div class=""><br class=""></div><div class="">Could you provide more information how you constructed your BEM-model?</div><div class=""><br class=""></div><div class="">best regards,</div><div class=""><br class=""><div class="">
Simon Homölle<br class="">PhD Candidate<br class="">Donders Institute for Brain, Cognition and Behaviour<br class="">Centre for Cognitive Neuroimaging<br class="">Radboud University Nijmegen<br class="">Phone: +31-(0)24-36-65059
</div>
<br class=""><div class=""><blockquote type="cite" class=""><div class=""><div class="h5"><div class="">On 02 Oct 2016, at 12:22, pooneh baniasad <<a href="mailto:pooneh.baniasad@gmail.com" target="_blank" class="">pooneh.baniasad@gmail.com</a>> wrote:</div><br class="m_-6321561874137257934Apple-interchange-newline"></div></div><div class=""><div class=""><div class="h5"><div dir="ltr" class=""><div class="gmail_default" style="font-size:large"><span style="font-size:12.8px" class="">Dear FieldTrip community</span><br clear="all" class=""></div><div class="gmail_default" style="font-size:large"><span style="font-size:12.8px" class=""><br class=""></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 class=""></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 class=""></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 class=""><br class=""></div></div><div class="">while the dimension of lead-field matrix is:
2000x122880 </div><div class=""><p class="m_-6321561874137257934gmail-p1">I use this function for calculating lead-field matrix:</p><p class="m_-6321561874137257934gmail-p1">LF = ft_compute_leadfield(DipPos, elec, VolBEM);</p></div></div><div class=""><div class="gmail_default">I do not understand why the number of raws are different!</div><div class="gmail_default"><br class=""></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 class=""></div><div class=""><div class="gmail_default">I will be so thankful if anyone can help me.</div><br class=""></div>-- <br class=""><div class="m_-6321561874137257934gmail-m_7370803151998605674gmail_signature"><div dir="ltr" class="">Bests<div class=""><br class=""></div><div class="">Pouneh Baniasad</div></div></div>
</div></div></div>
______________________________<wbr class="">_________________<br class="">fieldtrip mailing list<br class=""><a href="mailto:fieldtrip@donders.ru.nl" target="_blank" class="">fieldtrip@donders.ru.nl</a><br class=""><a href="https://mailman.science.ru.nl/mailman/listinfo/fieldtrip" target="_blank" class="">https://mailman.science.ru.nl/<wbr class="">mailman/listinfo/fieldtrip</a></div></blockquote></div><br class=""></div></div><br class="">______________________________<wbr class="">_________________<br class="">
fieldtrip mailing list<br class="">
<a href="mailto:fieldtrip@donders.ru.nl" class="">fieldtrip@donders.ru.nl</a><br class="">
<a href="https://mailman.science.ru.nl/mailman/listinfo/fieldtrip" rel="noreferrer" target="_blank" class="">https://mailman.science.ru.nl/<wbr class="">mailman/listinfo/fieldtrip</a><br class=""></blockquote></div><br class=""><br clear="all" class=""><div class=""><br class=""></div>-- <br class=""><div class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr" class="">Bests<div class=""><br class=""></div><div class="">Pouneh Baniasad</div></div></div>
</div>
_______________________________________________<br class="">fieldtrip mailing list<br class=""><a href="mailto:fieldtrip@donders.ru.nl" class="">fieldtrip@donders.ru.nl</a><br class="">https://mailman.science.ru.nl/mailman/listinfo/fieldtrip</div></blockquote></div><br class=""></div></body></html>