There are three different kinds of tracts, or bundles of axons which connect one part of the brain to another and to the spinal cord, within the white matter:
- Projection tracts extend vertically between higher and lower brain and spinal cord centers, and carry information between the cerebrum and the rest of the body.
- Commissural tracts cross from one cerebral hemisphere to the other through bridges called commissures. The great majority of commissural tracts pass through the large corpus callosum.
- Association tracts connect different regions within the same hemisphere of the brain. Long association fibers connect different lobes of a hemisphere to each other whereas short association fibers connect different gyri within a single lobe. Among their roles, association tracts link perceptual and memory centers of the brain.
The brain in general (and especially a child’s brain) can adapt to white-matter damage by finding alternative routes that bypass the damaged white-matter areas, and can therefore maintain good connections between the various areas of gray matter. (adapted from Wikipedia)
Diffusion tensor imaging (DTI) is a magnetic resonance imaging (MRI) technique that enables the measurement of the restricted diffusion of water in tissue in order to produce neural tract images instead of using this data solely for the purpose of assigning contrast or colors to pixels in a cross sectional image. (from wikipedia)
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