[FieldTrip] Source localization of MEG resting state data

최미경 cmk0803 at hbf.re.kr
Mon Jun 1 21:31:08 CEST 2015

Dear fieldtrip users,

I tried using DICS beamforming on MEG resting state data of healthy
(e.g. no task, no baseline, eyes opened)

I analyzed to localize oscillatory sources using beamformer techniques
according to the following tutorial.
(link: http://www.fieldtriptoolbox.org/tutorial/beamformer)
However, the output image was weird to be considered as resting data. I
would like someone to help me through source localization procedure.

*Q1. Is there something wrong in my script as below? *
cfg             = [];
cfg.output      = 'powandcsd';
cfg.method      = 'mtmfft';
cfg.foilim      = [8 12];
cfg.tapsmofrq   = 2;
cfg.channel     = {'MEG'};
cfg.keeptrials  = 'yes';
fft_rest = ft_freqanalysis(cfg, data_clean); % resting state MEG data
(after preprocessing)

%% Computing the leadfield matrices
cfg             = [];
cfg.grad        = fft_rest.grad;
cfg.vol         = vol;  % head model
cfg.grid        = grid; % source model
cfg.keeptrials  = 'yes';
cfg.normalize   = 'yes';
cfg.channel     = {'MEG'};
rest_grid  = ft_prepare_leadfield(cfg);

%% Source analysis
cfg             = [];
cfg.frequency   = 'all';
cfg.grad        = fft_rest.grad;
cfg.method      = 'dics';
cfg.grid        = rest_grid;
cfg.vol         = vol;
cfg.keeptrials  = 'yes';
cfg.keepfilter  = 'yes';
cfg.dics.lambda = 0;
cfg.dics.projectnoise = 'yes';
rest_source = ft_sourceanalysis(cfg, fft_rest);

mri_slice = ft_volumereslice([], mri) %mri: volumesegmented mri
cfg            = [];
cfg.parameter = 'avg.pow';
rest_sointer   = ft_sourceinterpolate(cfg, rest_source, mri_slice);

*Q2. Is there any way to check whether the beamforming is performed well?*

Any help would be greatly appreciated.


Mi Kyung CHOE
Department of Brain & Cognitive Sciences, Seoul National University
Human Brain Function Laboratory
E-mail : cmk0803 at hbf.re.kr, cmk0803 at meg.re.kr
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