Harvard researchers say that nerve fibers in the brain that carry thoughts and control actions crisscross on a grid that could one day be used to help diagnose mental disorders.

Researchers, who used a powerful new scanning tool to peer inside the brain, upended a long-held assumption that the fibers are jumbled, with no identifiable pattern, Bloomberg reported. Instead, they found a hidden order within regions that include the cerebrum and the brain stems, said a report Thursday in the journal Science.

The brain "is like Manhattan," said lead author Van Wedeen, a radiology professor at Harvard Medical School in Boston. "You have a grid of streets going left and right, and you have elevators going up and down." He called the results "a huge surprise."

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