While most people identify gray matter with the brain, less is known about the workings of the white-matter component of the neural anatomy-despite making up half of the brain's volume. This part of the brain and spinal cord takes its name from its cellular sheathing, a white fatty protein called myelin which insulates the nerve fibers. Until now, white matter has been less visible because its structures are missed by magnetic resonance imaging (MRI) and other techniques.
Now, because DTI has the ability to measure and model white matter tracts in the human brain, researchers believe there is new potential to discover the role of the white matter connections in psychiatric disorders, neurodegenerative disease and neuromuscular disorders. This new information on the role of white matter in the brain's functioning may also manifest ethical issues on how it should be used.