The 2026 Nobel Prize in Physiology or Medicine was awarded Monday to three scientists — Karl Deisseroth, 54, Peter Hegemann, 71, and Georg Nagel, 73 — for their discoveries concerning light-gated ion channels and optogenetics. The announcement at Sweden's Karolinska Institute kicks off this year's Nobel week. The three will share prize money of 12 million Swedish kronor (about $1.2 million).
Optogenetics has been called a revolutionary tool for neuroscience: it allows scientists to switch the activity of individual nerve cells on or off in a living brain with pulses of light. The Nobel Committee said the technique "opened a new era in neuroscience" and is now used in laboratories around the world to reveal the brain's mysteries.
"It's a tremendous step forward to be able to link nerve cells and their function to specific behaviours," said Anna Wedell, a member of the Nobel committee. "It's a completely new dimension of understanding of the function of the brain."
The story began in the early 1990s. Hegemann, then at the Max Planck Institute for Biochemistry in Germany, was fascinated by a simple question: how does Chlamydomonas, a single-celled green alga, swim toward light so rapidly? He hypothesized that a single protein could both detect light and function as an ion channel.
Teaming up with Nagel, then at the Max Planck Institute for Biophysics in Frankfurt, he identified that protein — channelrhodopsin. When illuminated by blue light, it opens a channel that lets ions flow through, generating an electrical impulse. In 2003, the two published findings showing that inserting the protein into human and hamster cells allowed electrical signals to be generated with light.
The decisive leap came from Deisseroth at Stanford University. He genetically engineered the brains of living mice so their nerve cells produced channelrhodopsin, demonstrating that neurons could be switched on and off with light. The 2005 paper enabled researchers to study the function of specific groups of neurons, and the term "optogenetics" was coined in 2006.
Using the method, researchers can now identify and even control the neural circuits governing "specific memories, feelings, and behaviors relevant for neurological and psychiatric disorders." Abdel El Manira, a neuroscientist on the Nobel Committee, said Hegemann and Nagel had "discovered the switch neuroscientists had long dreamed of."
This year's edition of the Nobel's traditional surprise phone call did not disappoint. Deisseroth, a self-described night owl, had been working late on a paper and had just drifted off when the committee called. "There were about 30 seconds where I had trouble forming words," he said at a Stanford press conference. "Now I don't think I'll be able to sleep for quite a while."
Nagel, meanwhile, was "on the terrace, in the sun" in Italy when he learned the news. "I didn't expect this, really! I have some friends who always say they are watching what's happening in October, and I always told them 'Keep cool.' As far as I know, only one patient has profited from optogenetics so far, so I thought it's still too early to get this prize in medicine."
Thomas Perlmann, secretary-general of the Nobel Committee, said he was able to reach all three winners by phone on Monday.
The medicine prize traditionally opens the annual Nobel announcements: physics follows on Tuesday, chemistry on Wednesday, literature on Thursday, and peace on Friday, with the economics prize announced on October 12. Last year's medicine prize went to American scientists Mary Brunkow and Fred Ramsdell and Japan's Shimon Sakaguchi for work on how the immune system spares healthy cells.