[FieldTrip] Fwd: ft_megplanar problem for planar gradient calculation

jan-mathijs schoffelen jan.schoffelen at donders.ru.nl
Thu Feb 23 10:20:29 CET 2012


Dear Ion,

In principle, you could do a synthetic planar grdient computation on the 102 magnetometer channels in your data. I don't think that this is supported by FieldTrip though.
Obviously, you cannot do the planar gradient computation on the other 204 channels, because they already represent the magnetic field gradient.

Best,

Jan-Mathijs

 
On Feb 23, 2012, at 10:11 AM, jan-mathijs schoffelen wrote:

> 
> 
> Begin forwarded message:
>> 
>> ---------- Forwarded message ----------
>> From: Ion Lavado <lavado at gmail.com>
>> Date: 2012/2/21
>> Subject: ft_megplanar problem for planar gradient calculation
>> To: fieldtrip-request at donders.ru.nl
>> 
>> 
>> Hello, i'm doing the cluster based permutations tests on time-frequency data tutorial. I'm using an Elekta neuromag with 306 channels. My problem comes when i try to calculate the planar gradient. This is what i do:
>> 
>> %************ READ WORD EVENT ************
>> cfg = [];                                          
>> cfg.dataset                 = '21_muti.fif';        
>> cfg.trialdef.eventtype      = 'STI101';
>> cfg.trialdef.prestim        = 1;
>> cfg.trialdef.poststim       = 1;
>> cfg.trialdef.eventvalue     = 1;                   
>> cfg = ft_definetrial(cfg);   
>> cfg.channel   = {'MEG'}; 
>> cfg.demean        = 'yes';
>> cfg.baselinewindow = [-0.5 0];
>> dataMuti21_words = ft_preprocessing(cfg);
>> %************ READ PICTURES EVENT ************
>> cfg = [];                                          
>> cfg.dataset                 = '21_muti.fif';        
>> cfg.trialdef.eventtype      = 'STI101';
>> cfg.trialdef.prestim        = 1;
>> cfg.trialdef.poststim       = 1;
>> cfg.trialdef.eventvalue     = 6;                   
>> cfg = ft_definetrial(cfg);   
>> cfg.channel   = {'MEG'}; 
>> cfg.demean        = 'yes';
>> cfg.baselinewindow = [-0.5 0];
>> dataMuti21_pictures = ft_preprocessing(cfg);
>> 
>> 
>> 
>> %******* CALCULATE PLANAR GRADIENT ******
>> cfg = [];
>> cfg.planarmethod = 'sincos';
>> cfg_neighb.method    = 'distance';
>> cfg.grad            = avg_words.grad;
>> cfg.neighbours       = ft_prepare_neighbours(cfg_neighb, dataMuti21_pictures);
>> avg_words_planar = ft_megplanar(cfg, dataMuti21_words);
>> avg_pictures_planar = ft_megplanar(cfg, dataMuti21_pictures);
>> 
>> 
>> HERE IS WHERE I GET THE ERROR: 
>> ??? Error using ==> ft_checkdata at 359
>> This function requires ctf151, ctf275, bti148, bti248, itab153, yokogawa160 or yokogawa64 data as input, but you are giving
>> neuromag306 data.
>> 
>> Error in ==> ft_megplanar at 107
>> data = ft_checkdata(data, 'datatype', {'raw' 'freq'}, 'feedback', 'yes', 'hassampleinfo', 'yes', 'ismeg', 'yes', 'senstype',
>> {'ctf151', 'ctf275', 'bti148', 'bti248', 'itab153', 'yokogawa160', 'yokoga 
>> 
>> 
>> Can't i use neuromag306 data type sens for this function? any solution? THANKS IN ADVANCE
>> 
>> Ion
> 
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Jan-Mathijs Schoffelen, MD PhD 

Donders Institute for Brain, Cognition and Behaviour, 
Centre for Cognitive Neuroimaging,
Radboud University Nijmegen, The Netherlands

Max Planck Institute for Psycholinguistics,
Nijmegen, The Netherlands

J.Schoffelen at donders.ru.nl
Telephone: +31-24-3614793

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