Diffusion spectrum image of the human cortex. Credit: Van J. Wedeen, Patric Hagmann, Olaf Sporns

The iconic image of the brain is a misshapen, yellowish lump. Existing technology can show which parts of the lump light up when people think, but a real understanding of how the brain works demands a better picture of the nerve fibers that ferry electrical signals between brain cells. Those fibers, however, are so small and tangled that researchers haven't been able to see them clearly.

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