STOCKHOLM — The 2026 Nobel Prize in Physiology or Medicine has been awarded to Karl Deisseroth, Peter Hegemann and Georg Nagel for their discoveries concerning light-gated ion channels — the foundation of optogenetics, a technique that lets scientists switch individual nerve cells on and off with light, the Nobel Assembly at Karolinska Institutet announced Monday.
The three will share the prize of 12 million Swedish crowns, equivalent to about $1.2 million.
Optogenetics “makes it possible to switch on, or off, the activity of individual nerve cells in a living brain,” the prize-givers said. “This method is now being used in laboratories around the world to reveal the brain’s mysteries.”
The story began with an alga. In the early 2000s, Peter Hegemann, then at the Max Planck Institute for Biochemistry in Germany, wondered how Chlamydomonas — a single-celled alga — senses and swims toward light. Teaming up with Georg Nagel, then at the Max Planck Institute for Biophysics in Frankfurt, he discovered channelrhodopsin: a light-sensitive protein that acts like a switch. When blue light hits it, a channel opens, charged ions flow into the cell, and an electrical impulse fires — regardless of which cell carries the protein.
“They had just discovered the switch neuroscientists had long dreamed of,” Abdel El Manira, a neuroscientist and member of the Nobel Committee, said during the prize announcement.
Karl Deisseroth, at Stanford University, took the discovery further. In 2005, he introduced the gene for channelrhodopsin into nerve cells from rats and showed that illuminating the cells with blue light could trigger a nerve signal. Two years later, he made the technique work in the brains of living mice — giving researchers a way to control specific neurons and map the circuits behind memories, emotions and behaviors.
“It is a completely new dimension of understanding of the function of the brain,” said Anna Wedell, a member of the Nobel committee.
Using optogenetics, researchers have mapped neural circuits governing memories, feelings and behaviors relevant to neurological and psychiatric disorders. In clinical medicine, researchers are using the method in attempts to restore sight in people with visual impairment, and the field may one day lead to treatments for Parkinson’s disease and epilepsy.
“Optogenetics has fundamentally altered our understanding of the brain,” the Nobel Assembly said. “Every day brings new discoveries, helping to solve one of humanity’s great mysteries: how our incredible brain works.”
Deisseroth, 54, an American psychiatrist and neurologist, is a professor of bioengineering and of psychiatry and behavioral sciences at Stanford University and the Howard Hughes Medical Institute. Hegemann, 71, is the Hertie Senior Professor of Neuroscience at Humboldt University in Berlin. Nagel, 73, is a professor of molecular plant physiology at the University of Würzburg.
The laureates will receive their prizes — a diploma, a gold medal and the shared check — from King Carl XVI Gustaf at a formal ceremony in Stockholm on Dec. 10, the anniversary of Alfred Nobel’s death in 1896.
The medicine prize traditionally opens Nobel week. The physics prize will be announced Tuesday, chemistry on Wednesday, literature on Thursday, peace on Friday, and economics on Oct. 12.
Last year, American scientists Mary Brunkow and Fred Ramsdell and Japan’s Shimon Sakaguchi won the medicine prize for work shedding light on how the immune system spares healthy cells.
