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

  FT_HEADMODEL_SINGLESPHERE creates a volume conduction model of the
  head by fitting a spherical model to a set of points that describe
  the head surface.
  For MEG this implements Cuffin BN, Cohen D.  "Magnetic fields of
  a dipole in special volume conductor shapes" IEEE Trans Biomed Eng.
  1977 Jul;24(4):372-81.
  Use as
    headmodel = ft_headmodel_singlesphere(mesh, ...)
  Optional arguments should be specified in key-value pairs and can include
    conductivity     = number, conductivity of the sphere