<html><head></head><body bgcolor='#FFFFFF' style='font-size:12px;background-color:#FFFFFF;font-family:Verdana, Arial, sans-serif;'>Hi Elenea,<br/><br/>I am still wondering about the scaling in the plots you send - could you rescale them such that the max can be seen in the combined plot?<br/><br/>Best ,<br/>Michael<br/><br/><br/><blockquote style="border-left: 2px solid blue; margin-left: 5px; padding-left: 5px; padding-top: 5px;"><hr/><b>Von:</b> "Elena Orekhova" <Elena.Orekhova@neuro.gu.se><br/><b>Gesendet:</b> Jun 2, 2011 8:03:16 PM<br/><b>An:</b> "Email discussion list for the FieldTrip project" <fieldtrip@donders.ru.nl><br/><b>Betreff:</b> Re: [FieldTrip] combining magnetometers and planad gradiometers for analysis<br/><br/><div style="font-size: 12px; background-color: rgb(255, 255, 255); font-family: Verdana,Arial,sans-serif;"><div style="direction: ltr; font-family: Tahoma; color: rgb(0, 0, 0); font-size: 10pt;">@font-face { font-family: "\FF2D \FF33 \660E \671D "; }@font-face { font-family: "Verdana"; }@font-face { font-family: "Cambria Math"; }@font-face { font-family: "Calibri"; }@font-face { font-family: "Cambria"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: Cambria; }.MsoChpDefault { font-family: Cambria; }div.WordSection1 { page: WordSection1; }<p class="MsoNormal"><span style="font-family: Calibri;">Dear </span><span style="font-family: Calibri; background: none repeat scroll 0% 0% white;">Michael, </span></p><p class="MsoNormal"><span style="font-family: Calibri; background: none repeat scroll 0% 0% white;"> </span></p><p class="MsoNormal" style=""><span style="font-family: Calibri; background: none repeat scroll 0% 0% white;">I did normalize the data </span></p><p class="MsoNormal" style=""><span style="font-family: Calibri; background: none repeat scroll 0% 0% white;">(</span><span style="font-size: 10pt; font-family: Courier; color: black;">sourcepst.avg.nai=sourcepst.avg.pow./sourcepre.avg.pow</span><span style="font-family: Calibri; background: none repeat scroll 0% 0% white;">) </span></p><p class="MsoNormal" style=""><span style="font-family: Calibri; background: none repeat scroll 0% 0% white;">as it was suggested in the tutorial.<span style=""> </span></span></p><p class="MsoNormal"><span style="font-family: Calibri; background: none repeat scroll 0% 0% white;">I used the same scales in all plots for comparison purposes. If<span style=""> </span>automatic scaling is used the result for MAG+GRA does not look any better (see attachment). </span></p><p class="MsoNormal"><span style="font-family: Calibri; background: none repeat scroll 0% 0% white;"> </span></p><p class="MsoNormal"><span style="font-size: 9pt; font-family: Verdana; background: none repeat scroll 0% 0% white;">>What you could do as a workaround is to average the separate results with a weighting per voxel and that >is corresponding to the squared norms of the leadfields for the respective modalities for a given voxel , this >would guarantee equal amounts of backprojected noise from both modalities (if I'm not mistaken).</span></p><p class="MsoNormal"><span style="font-size: 9pt; font-family: Verdana; background: none repeat scroll 0% 0% white;"> </span></p><p class="MsoNormal" style=""><span style="font-size: 9pt; font-family: Verdana; background: none repeat scroll 0% 0% white;">Thank you for your suggestion.<span style=""> </span>I may use it as a last resort.<span style=""> </span>Hopefully, there is still a way to get more optimal solution using both GRA and MAG in the same analysis...</span></p><p class="MsoNormal"><span style="font-size: 9pt; font-family: Verdana; background: none repeat scroll 0% 0% white;"> </span></p><p class="MsoNormal"><span style="font-size: 9pt; font-family: Verdana; background: none repeat scroll 0% 0% white;"> </span></p><p class="MsoNormal"><span style="font-family: Calibri; background: none repeat scroll 0% 0% white;">Elena</span></p><div style="font-family: Times New Roman; color: rgb(0, 0, 0); font-size: 16px;"><hr/><div id="divRpF587609" style="direction: ltr;"><font color="#000000" face="Tahoma" size="2"><b>From:</b> fieldtrip-bounces@donders.ru.nl [fieldtrip-bounces@donders.ru.nl] on behalf of Elena Orekhova [Elena.Orekhova@neuro.gu.se]<br/><b>Sent:</b> Thursday, June 02, 2011 6:22 PM<br/><b>To:</b> Email discussion list for the FieldTrip project<br/><b>Subject:</b> Re: [FieldTrip] combining magnetometers and planad gradiometers for analysis</font><br/> </div><div> </div><div><div style="direction: ltr; font-family: Tahoma; color: rgb(0, 0, 0); font-size: 10pt;">BODY {direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;}<p class="MsoNormal"><span style="font-family: Calibri;">Dear </span><span style="font-family: Calibri; background: none repeat scroll 0% 0% white;">Michael, </span></p><p class="MsoNormal"><span style="font-family: Calibri; background: none repeat scroll 0% 0% white;"> </span></p><p class="MsoNormal"><span style="font-family: Calibri; background: none repeat scroll 0% 0% white;">I have tried to multiply the leadfield by -1 as you suggested:</span></p><p class="MsoNormal"><span style="font-size: 11pt; font-family: Calibri; color: rgb(31, 73, 125); background: none repeat scroll 0% 0% white;"> </span></p><p class="MsoNormal" style=""><span style="font-size: 10pt; font-family: Courier; color: blue;">for</span><span style="font-size: 10pt; font-family: Courier; color: black;"> i = 1 : size (grid.leadfield, 2)</span></p><p class="MsoNormal" style=""><span style="font-size: 10pt; font-family: Courier;"><span style=""> </span>grid.leadfield{i}(3:3:306, :) = -1*grid.leadfield{i}(3:3:306, :);</span></p><p class="MsoNormal" style=""><span style="font-size: 10pt; font-family: Courier; color: blue;">end</span></p><p class="MsoNormal" style=""><span style="font-family: Calibri;"> </span></p><p class="MsoNormal" style=""><span style="font-family: Calibri;">This had no effect on the </span><span style="font-family: Calibri; color: rgb(160, 32, 240);">'lcmv'</span><span style="font-family: Calibri;"> output. I attached the pictures for ‘GRA only, ’MAG only’ and ‘GRA + MAG’</span></p><p class="MsoNormal"><span style="font-family: Calibri;"> </span></p><p class="MsoNormal"><span style="font-family: Calibri;">In this experiment I measured evoked field in response to <span style=""> </span>the unilateral (left) click. </span></p><p class="MsoNormal"><span style="font-family: Calibri;">The source is expected to be in the right superior temporal cortex. <span style=""> </span>This is the case <span style=""> </span>for </span><span style="font-family: Calibri;"><span style=""> </span>‘GRA only' and ’MAG only’ datasets. The combined sensors give meaningless result.</span></p><p class="MsoNormal"><span style="font-family: Calibri;"> </span></p><p class="MsoNormal"><span style="font-family: Calibri;">Elena</span></p><div> </div><div style="font-family: Times New Roman; color: rgb(0, 0, 0); font-size: 16px;"><hr/><div id="divRpF409531" style="direction: ltr;"><font color="#000000" face="Tahoma" size="2"><b>From:</b> fieldtrip-bounces@donders.ru.nl [fieldtrip-bounces@donders.ru.nl] on behalf of Michael Wibral [michael.wibral@web.de]<br/><b>Sent:</b> Wednesday, June 01, 2011 4:04 PM<br/><b>To:</b> Email discussion list for the FieldTrip project<br/><b>Subject:</b> Re: [FieldTrip] combining magnetometers and planad gradiometers for analysis</font><br/> </div><div> </div><div>Dear Elena,<br/><br/>could you give the following a try: invert (*-1) the leadfileds for one of the two sensor types. Let me know what happens.<br/>I would also be interested in taking a look at the results - maybe you could sent images off-list: Michael.Wibral <at> web.de.<br/><br/>Michael<br/><br/><br/><br/><blockquote style="border-left: 2px solid blue; margin-left: 5px; padding-left: 5px; padding-top: 5px;"><hr/><b>Von:</b> "Elena Orekhova" <Elena.Orekhova@neuro.gu.se><br/><b>Gesendet:</b> Jun 1, 2011 12:23:29 PM<br/><b>An:</b> "fieldtrip@donders.ru.nl" <fieldtrip@donders.ru.nl><br/><b>Betreff:</b> [FieldTrip] combining magnetometers and planad gradiometers for analysis<br/><br/><div><div style="direction: ltr; font-family: Tahoma; color: rgb(0, 0, 0); font-size: 10pt;">@font-face { font-family: "Arial"; }@font-face { font-family: "Times"; }@font-face { font-family: "\FF2D \FF33 \660E \671D "; }@font-face { font-family: "Cambria Math"; }@font-face { font-family: "Cambria"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0cm 0cm 0.0001pt; font-size: 12pt; font-family: Cambria; }p { margin-right: 0cm; margin-left: 0cm; font-size: 10pt; font-family: Times; }.MsoChpDefault { font-family: Cambria; }div.WordSection1 { page: WordSection1; }<p><span style="font-size: 12pt; font-family: Arial;">Dear fieldtrippers, </span></p><p class="MsoNormal" style=""><span style="font-family: Arial;">This message is mainly for Neuromag users. </span></p><p class="MsoNormal" style=""><span style="font-family: Arial;"> </span></p><p class="MsoNormal" style=""><span style="font-family: Arial;">When I do<span style=""> </span>'lcmv' beamforming analysis separately on planar gradiometers or magnetometers, I get quite meaningful results.</span></p><p class="MsoNormal" style=""><span style="font-family: Arial;">If I combine the two types of sensors without weighting, the result is meaningless.</span></p><p class="MsoNormal" style=""><span style="font-family: Arial;">Apparently, the algorithm does not take care of different scales and units of the GRA and MAG measurements.<span style=""> </span>Does anybody know how to deal with this problem?</span></p><p class="MsoNormal" style=""><span style="font-family: Arial;"> </span></p><p class="MsoNormal" style=""><span style="font-family: Arial;"> </span></p><p class="MsoNormal" style=""><span style="font-family: Arial;">Elena</span></p><p><span style="font-size: 12pt; font-family: Arial;"> </span></p><div> </div></div></div></blockquote></div></div></div></div></div></div></div></blockquote></body></html>