[FieldTrip] (no subject)

victoria schroeder vic.schroeder2 at gmail.com
Fri Jan 15 12:09:07 CET 2016


Dear Tzvetan,

I did not do any planar transformation with the gradiometers. I only did
the ft_combineplanar. Should i also omit that?

Cheers
Victoria

2016-01-15 10:26 GMT+00:00 victoria schroeder <vic.schroeder2 at gmail.com>:

> 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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>
>
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