As applied to neuroimaging, this magnetic resonance imaging (also known as diffusion tractography) uses information about the direction of water movement in white matter to determine the size and orientation of its constituent fiber tracts. The underlying principle stems for the fact that when water in unobstructed at body temperature, then the water molecules move around at random, while in the brain they more preferentially along the lines of nerve fiber bundles. It amounts to combining diffusion tensor imaging with functional MRI, which allows complementary identification of brain areas that are active during functional tasks. In this respect, it allows in vivo mapping of functional centers, with the potential to show the ways in which activated centers communicate with each other. Thus, both brain function and connectivity can be probed during a single examination.
See Blood Oxygenation Level Dependent Contrast (BOLD signal), Brain (neuro-) imaging, Diffusion anisotropy, Diffusion tensor imaging, Functional magnetic imaging (fMRI), Human Connectome Project (HCP), Neuroimaging studies