“It’s like there’s a continent there, and we are nibbling along the shores,’’ said Dr. Van Wedeen, a physicist and radiologist at the Martinos Center for Biomedical Imaging at Massachusetts General Hospital.
“Neural fibers in the brain are too tiny to image directly, so scientists map them by measuring the diffusion of water molecules along their length. The scientists first break the MRI image into ‘voxels,’ or three-dimensional pixels, and calculate the speed at which water is moving through each voxel in every direction. The researchers can infer the most likely path of the various nerve fibers (red and blue lines) passing through that spot. The result is a detailed diagram like that of the brain stem.” – Emily Singer