<html><head></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; ">Hi Michael y Elena,<div><br></div><div>I am following your discussion with great interest as I have just started to work with Neuromag data. As FT uses the MNE toolbox to read the data I assume that the SSP vectors are applied to the data during reading the data. However, the SSP vectors are stored in "data.hdr.orig.projs". However, when I go on with averaging in the ERF from timelockanalysis I cannot find this info. So my question is, does FT apply the SSP vectors later on also to the leadfield when calculating it? I assume that not, as the SSP vectors are not passed on further. How can I apply the SSP vectors to the leadfield to get correct results?</div><div><br></div><div>Best and thanks,</div><div><br></div><div>STephan</div><div><br><div><div>El 02/06/2011, a las 19:20, Michael Wibral escribió:</div><br class="Apple-interchange-newline"><blockquote type="cite"><div bgcolor="#FFFFFF" style="font-size:12px;background-color:#FFFFFF;font-family:Verdana, Arial, sans-serif;">Hi Elena,<br><br>I assume that you were well aware of the difficulties in beamforming evoked activty and baseline normalisation and these things, your results really look that way. I mus say I am quite puzzled by the results - could it be a color scaling problem in the plot? I think this mmay be a problem because most of your plot is a peak power, only a tiny corner seems to be in a low-amplitude range.<br><br>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).<br><br>Michael<br>PS: I am away for a couple of days, but after that, I'll be happy to resume this discussion.<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" <<a href="mailto:Elena.Orekhova@neuro.gu.se">Elena.Orekhova@neuro.gu.se</a>><br><b>Gesendet:</b> Jun 2, 2011 6:22:03 PM<br><b>An:</b> "Email discussion list for the FieldTrip project" <<a href="mailto:fieldtrip@donders.ru.nl">fieldtrip@donders.ru.nl</a>><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: "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><div><span style="font-family: Calibri; background: none repeat scroll 0% 0% white;"> </span><br class="webkit-block-placeholder"></div><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><div><span style="font-size: 11pt; font-family: Calibri; color: rgb(31, 73, 125); background: none repeat scroll 0% 0% white;"> </span><br class="webkit-block-placeholder"></div><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><div style=""><span style="font-family: Calibri;"> </span><br class="webkit-block-placeholder"></div><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><div><span style="font-family: Calibri;"> </span><br class="webkit-block-placeholder"></div><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><div><span style="font-family: Calibri;"> </span><br class="webkit-block-placeholder"></div><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> <a href="mailto:fieldtrip-bounces@donders.ru.nl">fieldtrip-bounces@donders.ru.nl</a> [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> <a href="http://web.de">web.de</a>.<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" <<a href="mailto:Elena.Orekhova@neuro.gu.se">Elena.Orekhova@neuro.gu.se</a>><br><b>Gesendet:</b> Jun 1, 2011 12:23:29 PM<br><b>An:</b> "<a href="mailto:fieldtrip@donders.ru.nl">fieldtrip@donders.ru.nl</a>" <<a href="mailto:fieldtrip@donders.ru.nl">fieldtrip@donders.ru.nl</a>><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><div style=""><span style="font-family: Arial;"> </span><br class="webkit-block-placeholder"></div><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><div style=""><span style="font-family: Arial;"> </span><br class="webkit-block-placeholder"></div><div style=""><span style="font-family: Arial;"> </span><br class="webkit-block-placeholder"></div><p class="MsoNormal" style=""><span style="font-family: Arial;">Elena</span></p><div><span style="font-size: 12pt; font-family: Arial;"> </span><br class="webkit-block-placeholder"></div><div> </div></div></div></blockquote></div></div></div></div></blockquote></div>
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<span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div><br class="Apple-interchange-newline">________________________________________________________</div><div>Stephan Moratti, PhD<br><br></div><div>see also: <a href="http://web.me.com/smoratti/">http://web.me.com/smoratti/</a><br><br></div><div>Universidad Complutense de Madrid</div><div>Facultad de Psicología</div><div>Departamento de Psicología Básica I</div><div>Campus de Somosaguas</div><div>28223 Pozuelo de Alarcón (Madrid)</div><div>Spain</div><div><br></div><div>and</div><div><br></div><div>Center for Biomedical Technology</div><div>Laboratory for Cognitive and Computational Neuroscience</div><div>Parque Científico y Tecnológico de la Universidad Politecnica de Madrid<br>Campus Montegancedo</div><div>28223 Pozuelo de Alarcón (Madrid)</div><div>Spain<br><br><br>email: <a href="mailto:smoratti@psi.ucm.es">smoratti@psi.ucm.es</a><br>Tel.: +34 679219982<br><br></div></span></div></span></div></span></div></span></div></span></span>
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