[FieldTrip] problem with MEG leadfield

[s.rombetto at cib.na.cnr.it]

Hi everybody
I'm trying to generate a field for a simulated dipole using the  
command ft_dipolesimulation, for a MEG study.

I do the following:
-read the hdr

-import the sensor structure with the following lines
grad=hdr.grad;
radius = sqrt(sum(grad.chanpos.^2,2));
grad.chanpos = grad.chanpos./ [radius radius radius];
grad.label=hdr.label(1:306)';

-then I create the vol structure using the following code
vol = [];
vol.r = 12 * [0.88 0.92 1.00]; %   radii of spheres, the head radius is 12 cm
vol.c = [1 1/80 1];       % conductivity
vol.o = [0 0 0];

At this point I have the grad structure, and the vol structure.
Then I give all the options for the dipole simulation with the code

%% create a dipole simulation with a custom timecourse
cfg      = [];
cfg.vol  = vol;      % see above
cfg.grad = grad;     % see above
cfg.dip.pos = [0 0.5 0.3];
cfg.dip.mom = [1 0 0]';
cfg.dip.frequency = 10;     %Hz
cfg.ntrials = 10;
cfg.triallength = 20;        % seconds
cfg.fsample = 250;          % Hz

but when I try to esecute the line

raw1 = ft_dipolesimulation(cfg);

I find this error

??? Error using ==> ft_compute_leadfield at 301
unsupported volume conductor model for MEG

Error in ==> ft_dipolesimulation at 198
   lf = ft_compute_leadfield(dippos{trial}, sens, vol);


I really cannot understand why  volume conductor model is not supported.
Any suggestion? I'm pretty sure that the mistake is trivial, but I'm  
not able to see it.

Thank you!
Dott.ssa Sara Rombetto

  Istituto di Cibernetica
  "E. Caianiello"
  Via Campi Flegrei, 34
  80078 Pozzuoli (NA)
  Italy
  mob +39 3491530515
  tel +39 0818675361
  fax +39 0818675128


"I disapprove of what you say, but I will defend to the death your  
right to say
it." [Evelyn Beatrice Hall, The Friends Of Voltaire]

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