Karl Deisseroth, 54, of Stanford, Peter Hegemann, 71, of Humboldt University in Berlin and Georg Nagel, 73, of the University of Würzburg won the 2026 Nobel Prize in physiology or medicine for work on light-gated ion channels and optogenetics, a way to turn individual nerve cells on or off with light. The Nobel committee said the method "is now being used in laboratories around the world to reveal the brain's mysteries."