Systems, methods, and software are used for identifying fibers based at least in part on magnetic resonance imaging. A fiber tract atlas for a nervous system includes atlas voxels that each represent a different volume element of the nervous system； a first atlas voxel represents a first volume element of the nervous system. The fiber tract atlas also includes information on orientations of a first fiber tract in the first volume element of the nervous system. Magnetic resonance data is acquired from the nervous system of a subject. The magnetic resonance data includes data voxels； a first data voxel relates to the first atlas voxel. A diffusion vector is generated for the first data voxel based at least in part on the acquired magnetic resonance data. The fiber tract atlas is used to find a probability that the first data voxel represents the first fiber tract based at least in part on the generated diffusion vector and the information on the orientations of the first fiber tract in the first volume element.
