FieldTrip

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

  FT_MEGPLANAR computes planar MEG gradients gradients for raw data
  obtained from FT_PREPROCESSING or an average ERF that was computed using
  FT_TIMELOCKANALYSIS. It can also convert frequency-domain data that was
  computed using FT_FREQANALYSIS, as long as it contains the complex-valued
  fourierspcrm and not only the powspctrm.
 
  Use as
     [interp] = ft_megplanar(cfg, data)
 
  The configuration should contain
    cfg.planarmethod   = 'orig' | 'sincos' | 'fitplane' | 'sourceproject'
    cfg.channel        =  Nx1 cell-array with selection of channels (default = 'MEG'),
                          see FT_CHANNELSELECTION for details
    cfg.trials         = 'all' or a selection given as a 1xN vector (default = 'all')
 
  The methods orig, sincos and fitplane are all based on a neighbourhood
  interpolation. For these methods you need to specify
    cfg.neighbours     = neighbourhood structure, see FT_PREPARE_NEIGHBOURS
 
  In the 'sourceproject' method a minumum current estimate is done using a
  large number of dipoles that are placed in the upper layer of the brain
  surface, followed by a forward computation towards a planar gradiometer
  array. This requires the specification of a volume conduction model of
  the head and of a source model. The 'sourceproject' method is not supported for
  frequency domain data.
 
  A head model must be specified, see FT_FETCH_VOL, or alternatively 
  manually using
    cfg.vol.r       = radius of sphere
    cfg.vol.o       = [x, y, z] position of origin
 
  A dipole layer representing the brain surface must be specified with
    cfg.inwardshift = depth of the source layer relative to the head model surface (default = 2.5, which is adequate for a skin-based head model)
    cfg.spheremesh  = number of dipoles in the source layer (default = 642)
    cfg.pruneratio  = for singular values, default is 1e-3
    cfg.headshape   = a filename containing headshape, a structure containing a
                      single triangulated boundary, or a Nx3 matrix with surface
                      points
  If no headshape is specified, the dipole layer will be based on the inner compartment
  of the volume conduction model.
 
  The following cfg fields are optional:
    cfg.feedback
 
  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.
 
  See also FT_COMBINEPLANAR, FT_NEIGHBOURSELECTION