Locating Language: The neural circuitry for speech and language is typically localized in the left hemisphere of the brain, along a region called the Sylvian fissure that stretches from Broca's area to Wernicke's. Researchers are searching for the genes that wire these regions and produce the uniquely human capacity for speech. Broca's area, highlighted above in green, is associated with speech and language output. Wernicke's area, highlighted in red, is associated with language comprehension. Credit: John MacNeill

Daniel Geschwind reaches up to his office bookshelf, takes down a three-dimensional puzzle of the human brain, and begins trying to snap the plastic pieces together. A neurogeneticist at the University of California, Los Angeles, Geschwind hopes the puzzle will help him describe the parts of the brain that control speech and language. But for the life of him, he can't figure out how the left and right hemispheres attach. "I'm really bad spatially, so don't make fun of me," he pleads. "It's like I'm having a little stroke or something. I'll get it together, and then I'll figure it out."

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