FieldTrip

Note that this reference documentation is identical to the help that is displayed in Matlab when you type “help ft_prepare_singleshell”.

  FT_PREPARE_SINGLESHELL creates a simple and fast method for the MEG forward
  calculation for one shell of arbitrary shape. This is based on a
  correction of the lead field for a spherical volume conductor by a
  superposition of basis functions, gradients of harmonic functions
  constructed from spherical harmonics.
 
  Use as
    vol = ft_prepare_singleshell(cfg, seg), or
    vol = ft_prepare_singleshell(cfg, mri), or
    vol = ft_prepare_singleshell(cfg)
 
  If you do not use a segmented MRI, the configuration should contain
    cfg.headshape   = a filename containing headshape, a structure containing a
                      single triangulated boundary, or a Nx3 matrix with surface
                      points
    cfg.numvertices = number, to retriangulate the mesh with a sphere (default = 3000)
                      instead of specifying a number, you can specify 'same' to keep the
                      vertices of the mesh identical to the original headshape points
 
  The following options are relevant if you use a segmented MRI
    cfg.smooth      = 'no' or the FWHM of the gaussian kernel in voxels (default = 5)
    cfg.sourceunits = 'mm' or 'cm' (default is 'cm')
    cfg.threshold   = 0.5, relative to the maximum value in the segmentation
 
  To facilitate data-handling and distributed computing with the peer-to-peer
  module, this function has the following option:
    cfg.inputfile   =  ...
  If you specify this option the input data will be read from a *.mat
  file on disk. This mat files should contain only a single variable named 'mri',
  corresponding to the input structure.
 
  This function implements
    G. Nolte, "The magnetic lead field theorem in the quasi-static
    approximation and its use for magnetoencephalography forward calculation
    in realistic volume conductors", Phys Med Biol. 2003 Nov 21;48(22):3637-52.