[FieldTrip] single trial beamforming

Frederic Roux fredericroux at hotmail.de
Tue Feb 8 16:16:56 CET 2011


Dear list-members,

I would like to compute a common frequency specific DICS spatial filter for my baseline and post-stimulus time window
as an average across trials, and then use this filter on a trial by trial basis to do the beam-forming
for the baseline and post-stimulus time window separately.

The reason is that I would like to localize the generators of sustained task-related beta-band activity (1.2 seconds).

The code I am planning to use looks as follows:
    
    cfg                 = [];
   
 cfg.channel = {'MEG' '-MLP12' '-MLT41' '-MRC12'  '-MRC14' '-MRC25' 
'-MRP56' '-MRT21' '-MLT57' '-MLT52' '-MRF22' '-MRF13' '-MRF24' '-MRF43' 
'-MLO22' '-MLF25' '-MRO31' '-MRO21'};
    cfg.grid            = warped_grid.grid;
    cfg.vol             = warped_grid.hdm;
    cfg.frequency       = 15;
    cfg.method          = 'dics';
    cfg.projectnoise    = 'yes';
    cfg.keepfilter      = 'yes';
    cfg.lambda          = 0.05;
    cfg.dim             = [Nx Ny Nz];
    cfg.rawtrial        = 'no';
    cfg.keeptrials      = 'no';
    
    [common_filt]           = sourceanalysis(cfg,common_TF);
    cfg.grid.filter        = common_filt.avg.filter;
 
    cfg.rawtrial        = 'yes';
    cfg.keeptrials     = 'yes';
    [pre_source]           = sourceanalysis(cfg,pre_TF)
    [post_source]           =sourceanalysis(cfg,post_TF);


Can anyone tell me if this code would be ok?
I am not sure if is correct to specify the cfg.rawtrial = 'yes' 
option.

Any help would be appreciated.

Thanks, 
fred 		 	   		  
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