[FieldTrip] (no subject)

[victoria schroeder]

Thank you Tzvetan.

2016-01-03 20:18 GMT+00:00 Tzvetan Popov <tzvetan.popov at uni-konstanz.de>:

>
> Dear Victoria,
> the system you are working with is already equipped with two orthogonal
> planar gradiometer sensors. Thus you should not try to create planar
> gradients on the basis of the planar gradients. Yet you might want to use
> the magnetometers only. There you can represent the activity as if it was
> picked up by planar gradients. Could you please skip the planar
> transformation bit and redo your analysis?
> FieldTrip provides three types of layouts for the Neuromag system: *NM306all.lay
> NM306mag.lay NM306grad.lay*. For example if you want to plot
> magnetometers only you’d specify *cfg.layout = 'neuromag306mag.lay’;
> cfg.channel = 'MEG*1’*; Here MEG*1 refers to magnetometers and MEG*2 and
> MEG*3 would be the two orthogonal planar gradients respectively. Also the
> neighbours are provided as* neuromag306cmb_neighb.mat;
> neuromag306mag_neighb.mat; neuromag306planar_neighb.ma
> <http://neuromag306planar_neighb.ma>*t;. You might consider loading the
> structure of your choice directly.
> Here is an example tutorial that might help:
> http://www.fieldtriptoolbox.org/tutorial/natmeg/timefrequency
> Good luck,
> tzvetan
>
> Dear Fieldtrip team,
>
> I am currently working on data acquired from an elektra system (neuromag).
> I have done all the preprocessing and the ft_freqanalysis with the
> gradiometers only. I combined the gradiometers to create planar
> gradients.However , later when doing the statistics problems occur when i
> want to specify the channels. The error tells me that no degrees of freedom
> are found for the analysis. However, when i remove the cfg.channel form the
> script it runs through without an error. (please see code below).
> My question is whether the output of the stastistic is correct without
> specifying the channels? If not, does anybody have suggestions how to fix
> the problem?
>
> I have run into similar problems when wanting to plot the time frequency
> data from the planar gradients after having used ft_combineplanar. Here i
> cannot find a layout file that suits the output of ft_combineplanar. Thus,
> i cannot specify a cfg.layout. After ft_combineplanar i have 102 channels,
> however, the layouts provided by fieldtrip does not fit that number.
> Has anybody run into similar problems? Or does anybody know a possible
> solution?
>
> Thank you very much for any suggestions
> Victoria
>
> %combine planar
> cfg = [];
> cfg.method ='sum';
> %ComCon = ft_combineplanar(cfg,FreqCon);
> ComIncon = ft_combineplanar(cfg, FreqIncon);
>
> cfg = [];
> %cfg.channel          = {'MEG'};
> cfg.latency          = 'all';
> cfg.frequency        = [14.5 16];
> cfg.method           = 'montecarlo';
> cfg.statistic        = 'ft_statfun_indepsamplesT';
> cfg.correctm         = 'cluster';
> cfg.clusteralpha     = 0.05;
> cfg.clusterstatistic = 'maxsum';
> cfg.minnbchan        = 2;
> cfg.tail             = 0;
> cfg.clustertail      = 0;
> cfg.alpha            = 0.025;
> cfg.numrandomization = 500;
> cfg_neighb.method    = 'distance';
> cfg.neighbours       = ft_prepare_neighbours(cfg_neighb, data_orig);
>
> design = zeros(1,size(ComGrad_con.powspctrm,1) +
> size(ComGrad_incon.powspctrm,1));
> design(1,1:size(ComGrad_con.powspctrm,1)) = 1;
>
> design(1,(size(ComGrad_con.powspctrm,1)+1):(size(ComGrad_con.powspctrm,1)+...
>   size(ComGrad_incon.powspctrm,1))) = 2;
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>
>
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