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reference:ft_compute_leadfield [2018/08/23 14:43] (current)
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 +=====  FT_COMPUTE_LEADFIELD =====
 +
 +Note that this reference documentation is identical to the help that is displayed in MATLAB when you type "help ft_compute_leadfield"​.
 +
 +<​html><​pre>​
 +  <a href=/​reference/​ft_compute_leadfield><​font color=green>​FT_COMPUTE_LEADFIELD</​font></​a>​ computes a forward solution for a dipole in a a volume
 +  conductor model. The forward solution is expressed as the leadfield
 +  matrix (Nchan*3), where each column corresponds with the potential or field
 +  distributions on all sensors for one of the x,​y,​z-orientations of the
 +  dipole.
 + 
 +  Use as
 +    [lf] = ft_compute_leadfield(dippos,​ sens, headmodel, ...)
 +  with input arguments
 +    dippos ​      = position dipole (1*3 or Ndip*3)
 +    sens      = structure with gradiometer or electrode definition
 +    headmodel = structure with volume conductor definition
 + 
 +  The headmodel represents a volume conductor model, its contents
 +  depend on the type of model. The sens structure represents a sensor
 +  array, i.e. EEG electrodes or MEG gradiometers.
 + 
 +  It is possible to compute a simultaneous forward solution for EEG and MEG
 +  by specifying sens and grad as two cell-arrays,​ e.g.
 +    sens       = {senseeg, sensmeg}
 +    headmodel ​ = {voleeg, ​ volmeg}
 +  This results in the computation of the leadfield of the first element of
 +  sens and headmodel, followed by the second, etc. The leadfields of the
 +  different imaging modalities are subsequently concatenated.
 + 
 +  Additional input arguments can be specified as key-value pairs, supported
 +  optional arguments are
 +    '​reducerank' ​     = '​no'​ or number
 +    '​normalize' ​      = '​no',​ '​yes'​ or '​column'​
 +    '​normalizeparam' ​ = parameter for depth normalization (default = 0.5)
 +    '​weight' ​         = number or 1xN vector, weight for each dipole position (default = 1)
 +    '​backproject' ​    = '​yes'​ (default) or '​no',​ in the case of a rank reduction
 +                        this parameter determines whether the result will be
 +                        backprojected onto the original subspace
 + 
 +  The leadfield weight may be used to specify a (normalized)
 +  corresponding surface area for each dipole, e.g. when the dipoles
 +  represent a folded cortical surface with varying triangle size.
 + 
 +  Depending on the specific input arguments for the sensor and volume, this
 +  function will select the appropriate low-level EEG or MEG forward model.
 +  The leadfield matrix for EEG will have an average reference over all the
 +  electrodes.
 + 
 +  The supported forward solutions for MEG are
 +    single sphere (Cuffin and Cohen, 1977)
 +    multiple spheres with one sphere per channel (Huang et al, 1999)
 +    realistic single shell using superposition of basis functions (Nolte, 2003)
 +    leadfield interpolation using a precomputed grid
 +    boundary element method (BEM)
 + 
 +  The supported forward solutions for EEG are
 +    single sphere
 +    multiple concentric spheres (up to 4 spheres)
 +    leadfield interpolation using a precomputed grid
 +    boundary element method (BEM)
 + 
 +  See also <a href=/​reference/​ft_prepare_vol_sens><​font color=green>​FT_PREPARE_VOL_SENS</​font></​a>,​ <a href=/​reference/​ft_headmodel_asa><​font color=green>​FT_HEADMODEL_ASA</​font></​a>,​ <a href=/​reference/​ft_headmodel_bemcp><​font color=green>​FT_HEADMODEL_BEMCP</​font></​a>,​
 +  <a href=/​reference/​ft_headmodel_concentricspheres><​font color=green>​FT_HEADMODEL_CONCENTRICSPHERES</​font></​a>,​ <a href=/​reference/​ft_headmodel_dipoli><​font color=green>​FT_HEADMODEL_DIPOLI</​font></​a>,​ <a href=/​reference/​ft_headmodel_halfspace><​font color=green>​FT_HEADMODEL_HALFSPACE</​font></​a>,​
 +  <a href=/​reference/​ft_headmodel_infinite><​font color=green>​FT_HEADMODEL_INFINITE</​font></​a>,​ <a href=/​reference/​ft_headmodel_localspheres><​font color=green>​FT_HEADMODEL_LOCALSPHERES</​font></​a>,​ <a href=/​reference/​ft_headmodel_openmeeg><​font color=green>​FT_HEADMODEL_OPENMEEG</​font></​a>,​
 +  <a href=/​reference/​ft_headmodel_singleshell><​font color=green>​FT_HEADMODEL_SINGLESHELL</​font></​a>,​ <a href=/​reference/​ft_headmodel_singlesphere><​font color=green>​FT_HEADMODEL_SINGLESPHERE</​font></​a>,​
 +  <a href=/​reference/​ft_headmodel_halfspace><​font color=green>​FT_HEADMODEL_HALFSPACE</​font></​a>​
 +</​pre></​html>​