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

  FT_VOLUMELOOKUP can be used in to combine an anatomical or functional atlas with
  the source reconstruction results. You can use it for forward and reverse lookup.
 
  Given the ROI as anatomical or functional label, it looks up the locations and
  creates a mask (as a binary volume) based on the label. Given the ROI as point in
  the brain, it creates a sphere or box around that point. In these two case the
  function is to be used as:
    mask = ft_volumelookup(cfg, volume)
 
  Given a binary volume that indicates a region of interest or a point of
  interest, it looks up the corresponding anatomical or functional labels
  from the atlas. In this case the function is to be used as:
     labels = ft_volumelookup(cfg, volume)
 
  In both cases the input volume can be:
    mri    is the output of FT_READ_MRI
    source is the output of FT_SOURCEANALYSIS
    stat   is the output of FT_SOURCESTATISTICS
 
  The configuration options for a mask according to an atlas:
    cfg.inputcoord          = 'mni' or 'tal', coordinate system of the mri/source/stat
    cfg.atlas               = string, filename of atlas to use, see FT_READ_ATLAS
    cfg.roi                 = string or cell-array of strings, region(s) of interest from anatomical atlas
 
  The configuration options for a spherical/box mask around a point of interest:
    cfg.roi                 = Nx3 vector, coordinates of the points of interest
    cfg.sphere              = radius of each sphere in cm/mm dep on unit of input
    cfg.box                 = Nx3 vector, size of each box in cm/mm dep on unit of input
    cfg.round2nearestvoxel  = 'yes' or 'no' (default = 'no'), voxel closest to point of interest is calculated
                              and box/sphere is centered around coordinates of that voxel
 
  The configuration options for labels from a mask:
    cfg.inputcoord          = 'mni' or 'tal', coordinate system of the mri/source/stat
    cfg.atlas               = string, filename of atlas to use, see FT_READ_ATLAS
    cfg.maskparameter       = string, field in volume to be looked up, data in field should be logical
    cfg.maxqueryrange       = number, should be odd (default = 1)
 
  The configuration options for labels around a point of interest:
    cfg.output              = 'label'
    cfg.roi                 = Nx3 vector, coordinates of the points of interest
    cfg.inputcoord          = 'mni' or 'tal', coordinate system of the mri/source/stat
    cfg.atlas               = string, filename of atlas to use, see FT_READ_ATLAS
    cfg.maxqueryrange       = number, should be 1, 3, 5 (default = 1)
    cfg.querymethod         = 'sphere' searches voxels around the roi in a sphere (default)
                            = 'cube' searches voxels around the roi in a sphere
    cfg.round2nearestvoxel = 'yes' or 'no', voxel closest to point of interest is calculated (default = 'yes')
 
  The label output has a field "names", a field "count" and a field "usedqueryrange".
  To get a list of areas of the given mask you can do for instance:
       [tmp ind] = sort(labels.count,1,'descend');
       sel = find(tmp);
       for j = 1:length(sel)
         found_areas{j,1} = [num2str(labels.count(ind(j))) ': ' labels.name{ind(j)}];
       end
  In the "found_areas" variable you can then see how many times which labels are
  found. Note that in the AFNI brick one location can have 2 labels.
 
  Dependent on the input coordinates and the coordinates of the atlas, the
  input MRI is transformed betweem MNI and Talairach-Tournoux coordinates
  See http://www.mrc-cbu.cam.ac.uk/Imaging/Common/mnispace.shtml for more details.
 
  See http://www.fieldtriptoolbox.org/template/atlas for a list of templates and
  atlasses that are included in the FieldTrip release.
 
  See also FT_READ_ATLAS, FT_SOURCEPLOT