Mark Schnitzer, 37; Stanford University
He's created a microscope that can uncover the smallest bits of our thoughts
Walk into Mark Schnitzer's lab while an experiment is in progress, and you'll see mice scampering around tethered to wire leashes. Sounds like a standard research setup for a neuroscientist—until you consider what's in the Lilliputian headpieces the mice are wearing. The plastic contraptions hold strands of clear fiber a bit thicker than a human hair, each containing a lens powerful enough to focus on individual neurons. "See that little needle?" Schnitzer says, angling one of the delicate fibers so it catches the light. "We can insert it directly into a mouse's brain to view regions that weren't accessible before." These fibers are giving researchers their first look at how individual cells behave deep in the brain.
Schnitzer didn't always aspire to survey uncharted biological territory; he started graduate school at Princeton University intending to become a physicist. But while there, he became entranced by the possibilities of mapping parts of the human body that had previously seemed too small and remote to study. He first helped develop a way to measure the forces produced by minuscule molecular "motors" inside cells, and soon resolved to uncover the biggest anatomical mystery of all: how simple neurons, firing together, can add up to create thoughts and memories.
MRI and CAT scanners give doctors a comprehensive view of entire regions of the brain, but they can't show what happens at the cellular level. Schnitzer zooms in on individual neurons by injecting areas to be imaged with a fluorescent dye. He then threads his lens deep into the brain and shines a titanium-sapphire laser through it. The laser light has the right energy level to activate the dye, so only the targeted brain areas absorb the light and glow. This method produces crisp, haze-free images that provide close-up views of neurons at work.
"Mark's work will revolutionize neuroscience, providing a new window—literally—to watch neurons in the brain work as they guide behavior," says Baylor College of Medicine neurobiologist Ron Davis. Although Schnitzer now stays busy using his neuro-microscope to study the ways mice store and forget memories (and what happens when that process goes awry), much of the thrill of making a completely new tool is watching other scientists devise creative ways to use it. "One of the most exciting things," Schnitzer says, "is knowing that there's such a demand for this."
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