Liberles got hooked on sensory biology early on. His interest in the vagus nerve follows a decade of work revealing how the brain interprets and responds to the world. As an undergraduate, he was struck by how he could distinguish the fragrances of closely related compounds he synthesized for a chemistry course. “If you added one or two methyl groups, you changed the perception from grape to cherry to watermelon,” he says. “I was hooked on olfaction from that point.”
At the time, scientists were working out the molecular logic the brain uses to perceive thousands of odors. Liberles followed their work with interest. “It was really the molecular level of understanding – how beautiful it was – that was an inspiration,” he says. Liberles went on to earn a PhD in chemical biology at Harvard University and do a postdoc in the lab of Linda Buck, then an HHMI investigator, where he discovered two new families of olfactory receptors. “We thought we understood how our sense of smell worked, so these families were a surprise,” he says. In his own lab, Liberles used those receptors to unravel how odors and pheromones elicit specific responses in mice – how the whiff of a predator’s urine, for example, drives an animal to flee.