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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>Hi fellow Fieldtripers-<o:p></o:p></p><p class=MsoNormal> I am learning about the pros & cons of different methods for source localization. For some of my data sets, I want to localize evoked activity (ERFs). In one of them, I anticipated a single unilateral primary site of activation and MNE worked very nicely for this. In the second, I am using auditory stimuli and therefore anticipated bilaterally synchronous activity. As was to be expected, (I think) MNE gave a single site of activity near the midline. I tried a parallel approach, but specifying lcmv as the method for ft_sourceanalysis as follows:<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoPlainText>cfg = [];<o:p></o:p></p><p class=MsoPlainText>cfg.method = 'lcmv';<o:p></o:p></p><p class=MsoPlainText>cfg.grid = leadfield_02_stim1;<o:p></o:p></p><p class=MsoPlainText>cfg.vol = vol;<o:p></o:p></p><p class=MsoPlainText>cfg.lambda = 1e8;<o:p></o:p></p><p class=MsoPlainText>cfg.checksize = inf; %I’ve been inserting this and the next line because I’ve gotten error messages about the size. This didn’t happen before, but these lines avoid the problem<o:p></o:p></p><p class=MsoPlainText>cfg.checkconfig ='loose';<o:p></o:p></p><p class=MsoPlainText>source3CB24_02_stim1 = ft_sourceanalysis(cfg, tlkCB24_02_stim1)<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>The output has a time dimension 1x601, and a pos dimension of 8196x3 dimension, but the avg.pow is only 1x8196. I interpret this to mean that the analysis averaged the power over some time interval instead of computing the power in each leadfield position for each time point. When I use the mne method, the output is clearly power for each time point, and produces a beautiful movie, as indicated in the tutorial. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>My questions about the lcmv technique are:<o:p></o:p></p><p class=MsoListParagraph style='margin-left:27.0pt;text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>1.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>Is there a fundamental difference between the lcmv approach and the mne approach whereby it cannot compute the power at each time point, but only gives a single average value for a time period?<o:p></o:p></p><p class=MsoListParagraph style='margin-left:27.0pt;text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>2.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>If so, how do I specify the time interval of interest (ie that containing the main peak of the ERF) in ft_sourceanalysis?<o:p></o:p></p><p class=MsoListParagraph style='margin-left:27.0pt;text-indent:-.25in;mso-list:l0 level1 lfo1'><![if !supportLists]><span style='mso-list:Ignore'>3.<span style='font:7.0pt "Times New Roman"'> </span></span><![endif]>I thought one advantage of either MNE or LCMV was that I could indicate my a priori hypothesis of the anticipated localization of the source activity. Do I do this with cfg.grid? Is there a way to indicate the number of anticipated dipoles? <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks in advance for your help-<o:p></o:p></p><p class=MsoNormal>Beth.<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Beth Belluscio MD-PhD<o:p></o:p></p><p class=MsoNormal>Clinical Fellow<o:p></o:p></p><p class=MsoNormal>Human Motor Control Section<o:p></o:p></p><p class=MsoNormal>NINDS, NIH<o:p></o:p></p><p class=MsoNormal>301-402-3495<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>