Brain map: Software called BrainLab analyzes data collected during a specialized MRI scan of the author’s brain in order to create a neural wiring map. The image shows a cross-section. Specific subsets of wires are highlighted (the color indicates the direction of the wiring going through that slice). The cross-sections are computationally stitched together to create a three-dimensional image. Credit: Andrew Frew/Brainlab

A series of black-and-white snapshots is splayed across the screen, each capturing a thin slice of my brain. The gray-scale pictures would look familiar to anyone who has seen a brain scan, but these images are different. Andrew Frew, a neuroscientist at the University of California, Los Angeles, uses a cursor to select a small square. Thin strands like spaghetti appear, representing the thousands of neural fibers passing through it. A few clicks of the cursor and Frew refines the tract of fibers pictured on the screen, highlighting first my optic nerve, then the fibers passing through a part of the brain that's crucial for language, then the bundles of motor and sensory nerves that head down to the brain stem.

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