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<p style="margin-top:0;margin-bottom:0">Dear Fieldtrippers,</p>
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<p style="margin-top:0;margin-bottom:0">My name is Jane, and this is my first time posting a question to this community. First and foremost, I would like to apologise if my question is extremely trivial.</p>
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<p style="margin-top:0;margin-bottom:0">I am trying to perform source analysis using the Beamformer DICS approach on EEG data. My data has been preprocessed using the EEGlab toolbox, and in this particular instance I am only interested in 20 Hz source space
activity for time periods around event 'SS'.</p>
<p style="margin-top:0;margin-bottom:0">My question is very simple: is it normal to get NaNs in the avg.pow output of the source analysis? It seems to make sense; positions in the grid that do not have 20 Hz reconstructed activity would be represented by NaNs.
However, I'm a novice (in all aspects: Matlab, EEG analysis, and Fieldtrip), and for a sanity check, would like to confirm that getting NaNs in my source output is normal.</p>
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<p style="margin-top:0;margin-bottom:0">Here is the code I executed:</p>
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<div>%% Loading data</div>
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<div>[EEG] = pop_loadset('E:\preprocesseddata.set'); </div>
<div>EEG = pop_epoch( EEG, { 'SSstopDIN' }, [-0.5 0.8]); % Epoch to event of interest 'SS'</div>
<div>dataSS_epoched = eeglab2fieldtrip(EEG, 'preprocessing'); % Convert eeglab dataset to fieldtrip data</div>
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<div>%% Calculating the cross spectral density matrix</div>
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<div> cfg = [];</div>
<div> cfg.method = 'mtmfft';</div>
<div> cfg.taper = 'hanning';</div>
<div> cfg.output = 'powandcsd';</div>
<div> cfg.foi = 4:40;</div>
<div> cfg.keeptrials = 'no';</div>
<div> TFR_SS = ft_freqanalysis(cfg, dataSS_epoched);</div>
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<div>%% Computing leadfield </div>
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<div>cfg = [];</div>
<div>cfg.headmodel = vol; %using BEM head model from FT template</div>
<div>cfg.reducerank = 3; %default = 3 for EEG</div>
<div>cfg.elec = elec_aligned </div>
<div>cfg.grid.resolution = 0.5; % use a 3-D grid with a 0.5 cm resolution</div>
<div>cfg.grid.unit = 'cm';</div>
<div>[grid] = ft_prepare_leadfield(cfg);</div>
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<div>%% Source analysis (without contrasts; just testing source reconstruction for one condition first)</div>
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<div>cfg = [];</div>
<div>cfg.method = 'dics';</div>
<div>cfg.frequency = 20; </div>
<div>cfg.grid = grid;</div>
<div>cfg.headmodel = vol;</div>
<div>cfg.elec = elec_aligned;</div>
<div>sourceSS_nocon = ft_sourceanalysis(cfg, TFR_SS); % Here, <span style="font-family: Calibri, Helvetica, sans-serif, EmojiFont, "Apple Color Emoji", "Segoe UI Emoji", NotoColorEmoji, "Segoe UI Symbol", "Android Emoji", EmojiSymbols; font-size: 16px;">sourceSS_nocon.avg.pow
shows NaNs in some cells and not others</span></div>
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<p style="margin-top:0;margin-bottom:0"><img size="28967" contenttype="image/png" id="img114935" tabindex="0" style="max-width: 99.9%; user-select: none;" data-outlook-trace="F:1|T:1" src="cid:a458c15f-7cd8-4957-b19f-49686ec7517a"><br>
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<p style="margin-top:0;margin-bottom:0">My sincere thanks in advance!</p>
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<p class="MsoNormal"><span lang="EN-SG" style="">Best regards,</span></p>
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<p class="MsoNormal"><span lang="EN-SG" style="">Jane</span></p>
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<b><span style="font-size:9.0pt; font-family:"Verdana",sans-serif; color:black">Jane Tan, PhD Candidate</span></b><span style="font-size:11.5pt; font-family:"Segoe UI",sans-serif; color:#212121"></span></p>
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<b><span style="font-size:9.0pt; font-family:"Verdana",sans-serif; color:black">School of Psychology and Exercise Science | Murdoch University</span></b><span style="font-size:11.5pt; font-family:"Segoe UI",sans-serif; color:#212121"></span></p>
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<span style="font-size:9.0pt; font-family:"Verdana",sans-serif; color:black">Room 3.001 Social Science Building, 90 South Street, Murdoch WA 6150 <b>| </b>Email: Jane.Tan@murdoch.edu.au</span><span style="font-size:11.5pt; font-family:"Segoe UI",sans-serif; color:#212121"></span></p>
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<img class="EmojiInsert" style="" data-outlook-trace="F:1|T:1" src="cid:95c33115-83df-4674-9c4c-28935742fc23"><br>
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