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Images by Van Wedeen, Ruopeng Wang, Jeremy Schmahmann, and Guangping Dai of the MGH Martinos Center for Biomedical Imaging in Boston, MA; Patric Hagmann of EPFL and CHUV, Lausanne, Switzerland; and Jon Kaas of Vanderbilt University, Nashville, TN.
Brain Connections
Diffusion spectrum imaging, developed by neuroscientist Van Wedeen at Massachusetts General Hospital, analyzes magnetic resonance imaging (MRI) data in new ways, letting scientists map the nerve fibers that carry information between cells. These images, generated from a living human brain, show a reconstruction of the entire brain (1) and a subset of fibers (2). The red fibers in the middle and lower left of both images are part of the corpus callosum, which connects the two halves of the brain.
Mapping Diffusion
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. Te 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 (3).
By Emily Singer, MIT Technology Review, November/December 2008
