<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 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
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<br class=""><div><blockquote type="cite" class=""><div class="">On 02 Oct 2016, at 12:22, 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" 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="gmail-p1">I use this function for calculating lead-field matrix:</p><p class="gmail-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="gmail-m_7370803151998605674gmail_signature"><div dir="ltr" class="">Bests<div class=""><br class=""></div><div class="">Pouneh Baniasad</div></div></div>
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