STOCKHOLM: The 2026 Nobel Prize in physiology or medicine was awarded Monday to three scientists for developing a technique that uses light to decode the inner workings of the brain.
Karl Deisseroth, Peter Hegemann and Georg Nagel were honored for their work on optogenetics, a method that acts as a "light-sensitive switch," allowing scientists to map which cells are responsible for which functions in the brain, said Anna Wedell, a member of the Nobel Prize committee.
German researchers Hegemann, 71, and Nagel, 73, discovered a light-sensitive protein in algae known as channelrhodopsin. American scientist Deisseroth, 54, later transformed the protein into a light-controlled switch for nerve cells, the committee said in a statement.
That work has "laid the foundation for a new era in neuroscience," the committee added.
By using the method, researchers can identify and even control the neural circuits that govern "specific memories, feelings, and behaviors relevant for neurological and psychiatric disorders."
Deisseroth, a professor of bioengineering and psychiatry at Stanford University, had been working late on a paper and was just starting to drift to sleep when the Nobel committee called.
"My phone rang at my bedside. There was about 30 seconds when I had trouble forming words," he told a news briefing.
Nagel learned he was a recipient while "on the terrace, in the sun" in Italy.
"I didn't expect this, really!" he said. "I have some friends who always say they are watching what's happening in October when they are announcing it, and I always told them 'Keep cool.' There's only, so far, I know of one patient who profited from optogenetics so … I thought it's still too early to get this prize in medicine."
The award highlights the "profound impact of a field that has fundamentally changed how scientists understand the brain and nervous system," said David Pendlebury, head of research analysis at Clarivate's Institute for Scientific Information.
"The Nobel Committee's recognition underscores the extraordinary influence of this work, which has transformed neuroscience by enabling researchers to use light to precisely control and study neural activity," Pendlebury added.
The discovery began with Hegemann's curiosity about the behavior of single-celled algae known as Chlamydomonas, which can swim toward a light source. In the early 2000s, he and Nagel discovered channelrhodopsin, a protein found on the surface of Chlamydomonas that is unusually both light-sensitive and generates electrical impulses. Regardless of which cell they put the protein in, those cells became light-sensitive.
Deisseroth, who still works as a psychiatrist alongside his research, built on their discovery by introducing the gene that codes the protein into the nerve cells of rats. By illuminating the nerve cells, he was able around 2007 to control the movement of mouse whiskers.
The work marked the infancy of optogenetics, which now allows researchers to understand which nerve cells in the brain control different functions. The Nobel committee said scientists have since identified neural circuits that govern pain, social behaviors, thirst, food consumption, reward and attention.
Finding a way to learn about the role of specific brain regions in mental functions "transformed how we study malfunctioning circuits in mental disorders," said Andrea Benucci, a professor in biology and experimental psychology at Queen Mary University of London, in an email.
"The ability to activate or silence neurons in the brain using laser light has opened the door to unprecedented precision," Benucci told CNN.
The hope is optogenetics will lead to new medical treatments as well as a deeper understanding of psychiatric and neurological disorders such as depression, anxiety, schizophrenia, Alzheimer's disease and Parkinson's disease.
Researchers in optogenetics are attempting to restore vision in people who have become blind due to retinitis pigmentosa, a disease that destroys the eye's rods and cones.
"When they inserted a channelrhodopsin-like protein in the retina of a blind person, the person regained some vision. Using special glasses emitting light, the person was able to discern and grasp objects on a table," according to a release from the Nobel committee.
Another area of research seeks to harness optogenetics to improve cochlear implants for hearing loss.
The three laureates will equally split the 12 million Swedish krona ($1,200,000) prize pot. Four more Nobel Prizes — physics, chemistry, literature and peace — will be awarded later this week, before the Nobel Memorial Prize in Economic Science is awarded next Monday.
