This .zip file contains annotated fiber tracts from the BrainSpan project (http://brainspan.org/) for the Stage_4_19_pcw specimen.  The fiber tracts are stored as VTK files named as follows:

{age}_{structure_acronym}_{hemisphere}.vtk

See the BrainSpan white paper for structure acronym definitions.  The VTK file format represents each tract as a series of polygonal lines.  The top of the file first lists all of the (x,y,z) vertex coordinates in the file.  The bottom of the file consists of a set of vertex indices for each fiber tract.  For more details, see the VTK file format documentation (www.vtk.org/VTK/img/file-formats.pdf).

ParaView (http://www.paraview.org) is a free desktop data visualization application that will display VTK files.  To read the .vtk files programmatically, write a script using the Visualization Toolkit (a C++ data visualization library, http://vtk.org/).  Alternatively, because .vtk is a straightforward ASCII file format, writing a custom file parser is not difficult.
