FieldTrip

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

  FT_PREPARE_LOCALSPHERES creates a MEG volume conductor model with a sphere
  for every sensor. You can also use it to create a single sphere
  model that is fitted to the MRI or to the head shape points.
 
  Use as
    vol = ft_prepare_localspheres(cfg, seg), or
    vol = ft_prepare_localspheres(cfg, mri), or
    vol = ft_prepare_localspheres(cfg)
 
  The input configuration should contain
    cfg.grad         = structure with gradiometer definition, or
    cfg.gradfile     = filename containing gradiometer definition
    cfg.radius       = number, which points to select for each channel (default = 7 cm)
    cfg.baseline     = number, baseline of axial/planar gradiometer (default = 5 cm)
    cfg.feedback     = 'yes' or 'no' (default = 'yes')
    cfg.singlesphere = 'yes' or 'no', fit only a single sphere (default = 'no')
    cfg.headshape    = a filename containing headshape, a structure containing a
                       single triangulated boundary, or a Nx3 matrix with surface
                       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 = 'no')
    cfg.sourceunits = 'mm' or 'cm' (default = '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 options:
    cfg.inputfile   =  ...
    cfg.outputfile  =  ...
  If you specify one of these (or both) the input data will be read from a *.mat
  file on disk and/or the output data will be written to a *.mat file. These mat
  files should contain only a single variable, corresponding with the
  input/output structure.
 
  This function implements
    Huang MX, Mosher JC, Leahy RM.
    A sensor-weighted overlapping-sphere head model and exhaustive head model comparison for MEG
    Phys Med Biol. 1999 Feb;44(2):423-40