reference:ft_datatype_parcellation [FieldTrip]

===== FT_DATATYPE_PARCELLATION ===== Note that this reference documentation is identical to the help that is displayed in MATLAB when you type "help ft_datatype_parcellation". <html><pre> <a href=/reference/ft_datatype_parcellation>FT_DATATYPE_PARCELLATION</a> describes the FieldTrip MATLAB structure for parcellated cortex-based data and atlases. A parcellation can either be indexed or probabilistic (see below). A parcellation describes the tissue types for each of the surface elements. Parcellations are often, but not always labeled. A parcellatoin can be used to estimate the activity from MEG data in a known region of interest. A surface-based atlas is basically a very detailled parcellation with an anatomical label for each vertex. An example of a surface based Brodmann parcellation looks like this pos: [8192x3] positions of the vertices forming the cortical sheet tri: [16382x3] triangles of the cortical sheet coordsys: 'ctf' the (head) coordinate system in which the vertex positions are expressed unit: 'mm' the units in which the coordinate system is expressed brodmann: [8192x1 uint8] values from 1 to N, the value 0 means unknown brodmannlabel: {Nx1 cell} An alternative representation of this parcellation is pos: [8192x3] positions of the vertices forming the cortical sheet tri: [16382x3] triangles of the cortical sheet coordsys: 'ctf' the (head) coordinate system in which the vertex positions are expressed unit: 'mm' the units in which the coordinate system is expressed Brodmann_Area_1: [8192x1 logical] binary map representing the voxels belonging to the specific area Brodmann_Area_2: [8192x1 logical] binary map representing the voxels belonging to the specific area Brodmann_Area_3: [8192x1 logical] binary map representing the voxels belonging to the specific area ... The examples above demonstrate that a parcellation can be indexed, i.e. consisting of subsequent integer numbers (1, 2, ...) or probabilistic, consisting of real numbers ranging from 0 to 1 that represent probabilities between 0% and 100%. An extreme case is one where the probability is either 0 or 1, in which case the probability can be represented as a binary or logical array. The only difference to the source data structure is that the parcellation structure contains the additional fields xxx and xxxlabel. See <a href=/reference/ft_datatype_source>FT_DATATYPE_SOURCE</a> for further details. Required fields: - pos Optional fields: - tri, coordsys, unit Deprecated fields: - none Obsoleted fields: - none Revision history: (2012/latest) The initial version was defined in accordance with the representation of a voxel-based segmentation. See also <a href=/reference/ft_datatype>FT_DATATYPE</a>, <a href=/reference/ft_datatype_source>FT_DATATYPE_SOURCE</a>, <a href=/reference/ft_datatype_segmentation>FT_DATATYPE_SEGMENTATION</a> </pre></html>