[FieldTrip] Fwd: ft_megplanar problem for planar gradient calculation

Eelke Spaak eelke.spaak at donders.ru.nl
Thu Feb 23 10:19:25 CET 2012


Dear Ion,

ft_megplanar is designed to estimate planar gradient information from
axial gradiometer data. The Neuromag 306 system is equipped with
planar gradiometers, so the data you have is already reflecting the
planar magnetic gradient. In other words: there is no need to use
ft_megplanar, in your case.

Best,
Eelke

On 23 February 2012 10:11, jan-mathijs schoffelen
<jan.schoffelen at donders.ru.nl> 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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