Gauging Someone's "Mental Speed"

The above image is a DTI

The smarter the person, the faster information zips around the brain, a UCLA study finds. And this ability to think quickly apparently is inherited.

The study, published in the Journal of Neuroscience, looked at the brains and intelligence of 92 people. All the participants took standard IQ tests. Then the researchers studied their brains using a technique called diffusion tensor imaging, or DTI.