1. Any muscle that stretches, or tenses, some part of the body.
2. In mathematics, an abstract object representing a generalization of the vector concept and having a specified system of components that undergo certain types of transformation under changes of the coordinate system.

1. Measuring the movement of water in the brain, detecting areas where the normal flow of water is disrupted.

A disrupted flow of water indicates where there could be an underlying abnormality in the brain.

2. A new type of magnetic resonance technology which has, among other things, for the first time shown "white matter" in action, revealing its role in the brain.

Although gray matter (composed of neurons) does the brain's thinking and calculating, white matter (composed of myelin-coated axons, or long fibers of nerve cells), control the signals which neurons share, co-ordinating how well brain regions work together.

Diffusion tensor imaging (DTI) is done with the same kind of magnetic resonance imaging (MRI) machines found in hospitals; however, it involves a different type of magnetic field and different algorithms to create the many brain-image slices that are assembled into a three-dimensional picture.

An antisymmetric second-rank tensor whose elements are proportional to the electric and magnetic fields.