Magnetic resonance imaging (MRI) has illuminated the functions of many structures in the brain, but until recently the physical connections between these structures were considered “MRI invisible.” Not so anymore, as this picture illustrates: crisp outlines in red and yellow show white matter tracts running through and between the left and right hemispheres. This new MRI approach, called diffusion tensor imaging (DTI), tracks water diffusion along nerve fibers, exposing the microarchitecture of the brain. DTI promises not only to open up a new avenue of research into the brain’s wiring but also to give doctors a powerful diagnostic tool. When a white matter tract is damaged by a neurodegenerative disease, its cellular membranes no longer restrict water flow, and diffusion becomes more random. DTI can detect such degeneration, as a team at the University of Alberta demonstrated in patients with amyotrophic lateral sclerosis, or Lou Gehrig’s disease.
This article was originally published with the title "A New View"