Deisseroth graduated from high school at sixteen and won a scholarship to Harvard, where he planned to major in creative writing. Instead, he ended up getting a degree in biochemistry, and was admitted, at the age of twenty, to Stanford’s combined M.D. and Ph.D. program. Motivated by a desire to better understand human nature, he decided to pursue his Ph.D. in neuroscience. “I didn’t come in by asking, ‘How many bits per second can flow through a pathway?’ ” he says. “I came in—maybe from the literature exposure—wanting to know where feeling came from. How you could be uplifted by words. How imagination worked.”
He opened a spiral-bound notebook and began to fill pages with words and sketches, ideas for what he called an “endoskeleton” that would “digest away” the fats and the water. “The resulting structure can be studied in unprecedented detail,” he wrote. The idea became CLARITY, an acronym for “Clear Lipid-exchanged Anatomically Rigid Imaging/immunostaining-compatible Tissue hYdrogel.” CLARITY is Deisseroth’s second great contribution to neuroscience—a method for rendering cadaver brains completely transparent, save for the perfectly intact cells and nerve fibres.