<div dir="ltr"><font face="tahoma,sans-serif"><span class="Apple-style-span" style="font-family: arial; ">Dear Jan-Mathijs,</span></font><div><font face="tahoma,sans-serif"><font class="Apple-style-span" face="arial">Thanks for your quick answer!</font></font></div>
<div><font face="tahoma,sans-serif"><font class="Apple-style-span" face="arial">I will check the different possibilities. I think that the problem was in the stage the lead field computation.</font></font></div><div><font face="tahoma,sans-serif"><font class="Apple-style-span" face="arial">And yes, this is 4D data. </font></font></div>
<div><font face="tahoma,sans-serif"><font class="Apple-style-span" face="arial">Sharon.<br></font></font><br><div class="gmail_quote">On Mon, Aug 2, 2010 at 4:23 PM, jan-mathijs schoffelen <span dir="ltr"><<a href="mailto:jan.schoffelen@donders.ru.nl">jan.schoffelen@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">Hi Sharon,<div><br></div><div style="direction: rtl;">If the results are exactly the same, I guess the references have not been taken into account at all. Although it remains to be seen whether you gain a lot with this approach (my preferred alternative would be to clean the data from external noise using the references and taking into account the correction in the forward computation), it should be possible to do it in fieldtrip. To get it to work, you have to check whether the necessary information is present throughout your analysis pipeline. Importantly, when computing the covariance matrix in ft_timelockanalysis, you have to include the references. The same goes for the computation of the leadfields (if you use ft_prepare_leadfield for that). If this information is still present prior to your call to ft_sourceanalysis, you may want to check whether you have to specify cfg.channel (to include the references, rather than 'MEG' (which may be the default, and causes selection of close-to-the-head sensors only).</div>
<div>Just for the record: is it 4D-neuroimaging data you are working on?</div><div><br></div><div>Best wishes,</div><div><br></div><div>Jan-Mathijs</div><div><br></div><div><br><div><div><div></div><div class="h5"><div>On Aug 2, 2010, at 2:06 PM, sharon riwkes wrote:</div>
<br></div></div><blockquote type="cite"><div><div></div><div class="h5"><div dir="ltr"><font face="tahoma,sans-serif">Hi all,<br>I tried to do source localization, after beamforming with the LCMV method. I did it once for all the MEG channels, and once for MEG channels <u>AND the reference channels</u>. I was hoping that using the reference channels will improve the localization by ignoring noise coming from outside of the brain. <br>
However, I got the <u>exact same results for MEG+reference channels</u> as <u>for MEG alone!</u><br>Does anyone know how to include the reference channels effectively in the LCMV beamforming?<br>Thanks for your help,<br>
Sharon Riwkes.<br> <br></font></div></div></div><p>----------------------------------</p><p>The aim of this list is to facilitate the discussion between users of the FieldTrip toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis.</p>
<p> <a href="http://listserv.surfnet.nl/archives/fieldtrip.html" target="_blank">http://listserv.surfnet.nl/archives/fieldtrip.html</a></p><p> <a href="http://www.ru.nl/fcdonders/fieldtrip/" target="_blank">http://www.ru.nl/fcdonders/fieldtrip/</a></p>
</blockquote></div><br><div> <span style="border-collapse:separate;color:rgb(0, 0, 0);font-family:Helvetica;font-size:medium;font-style:normal;font-variant:normal;font-weight:normal;letter-spacing:normal;line-height:normal;text-align:auto;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px"><div style="word-wrap:break-word">
<div>Dr. J.M. (Jan-Mathijs) Schoffelen </div><div>Donders Institute for Brain, Cognition and Behaviour, <br>Centre for Cognitive Neuroimaging,<br>Radboud University Nijmegen, The Netherlands</div><div><a href="mailto:J.Schoffelen@donders.ru.nl" target="_blank">J.Schoffelen@donders.ru.nl</a></div>
<div>Telephone: 0031-24-3668063</div></div></span> </div><br></div></div><p>----------------------------------</p>
<p>The aim of this list is to facilitate the discussion between users of the FieldTrip toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis.</p>
<p> <a href="http://listserv.surfnet.nl/archives/fieldtrip.html" target="_blank">http://listserv.surfnet.nl/archives/fieldtrip.html</a></p>
<p> <a href="http://www.ru.nl/fcdonders/fieldtrip/" target="_blank">http://www.ru.nl/fcdonders/fieldtrip/</a></p>
</blockquote></div><br></div></div>
<p>----------------------------------</p>
<p>The aim of this list is to facilitate the discussion between users of the FieldTrip toolbox, to share experiences and to discuss new ideas for MEG and EEG analysis.</p>
<p> http://listserv.surfnet.nl/archives/fieldtrip.html</p>
<p> http://www.ru.nl/fcdonders/fieldtrip/</p>