Date: October 7, 2026
Reporter: Emilly Jordan
American scientist Karl Deisseroth and German researchers Peter Hegemann and Georg Nagel have been awarded the 2026 Nobel Prize in Physiology or Medicine for discoveries that transformed the study of the brain by allowing scientists to control individual nerve cells using light.
The Nobel Assembly at the Karolinska Institutet in Sweden announced the award on Monday, recognizing the three scientists for their “discoveries concerning light-gated ion channels and optogenetics.” The three laureates will share a prize of 12 million Swedish kronor, approximately US$1.2 million.
Their work gave neuroscientists a powerful way to activate or silence selected nerve cells in living brains with extraordinary precision. The technique, known as optogenetics, combines genetic modification with light to investigate how individual neurons contribute to memories, emotions, behaviour and other brain functions.
The breakthrough began not with human brain research, but with a single-celled green alga called Chlamydomonas. Hegemann became interested in how the organism detects and moves toward light. In the early 2000s, he and Nagel investigated proteins involved in this process and discovered channelrhodopsin, a light-sensitive protein that can function as a channel for electrically charged particles.
When exposed to blue light, channelrhodopsin opens and allows ions to flow through the cell membrane, generating an electrical signal. Hegemann and Nagel demonstrated that the protein could make other cells sensitive to light, providing the foundation for eventually controlling nerve cells.
Deisseroth subsequently took the discovery into neuroscience. His team introduced the gene responsible for channelrhodopsin into nerve cells from rats. When researchers illuminated those cells with blue light, they were able to trigger electrical activity. Deisseroth later demonstrated that the technique could work in the brains of living mice, creating a method for switching selected neurons on and off with light.
The approach was eventually named optogenetics and rapidly became one of the most important tools in modern neuroscience. Unlike older techniques that often allowed scientists to observe broad areas of the brain, optogenetics makes it possible to target particular types of nerve cells and test whether their activity directly causes a specific behaviour or biological response.
“This method makes it possible to switch on, or off, the activity of individual nerve cells in a living brain,” Thomas Perlmann, secretary-general of the Nobel Assembly, said following the announcement.
The Nobel Committee said the technology has opened a new era in neuroscience because it allows researchers to investigate how neural circuits work with a level of precision that was previously impossible. Researchers can now examine which groups of neurons are involved in particular memories, emotions and behaviours and determine how those cells interact.
The technique has also become an important research tool for studying neurological and psychiatric disorders. Scientists have used optogenetic methods in animal models to investigate conditions including schizophrenia, Alzheimer's disease, Parkinson's disease, epilepsy, depression and addiction.
One of the most important potential applications is medicine. Researchers are investigating whether optogenetics can eventually be used to treat neurological and sensory disorders in humans. Among the areas being studied is vision restoration for people with retinitis pigmentosa, a progressive inherited eye disease that can lead to severe vision loss or blindness.
In experimental approaches, researchers introduce light-sensitive proteins into retinal cells and then use specially designed light sources to stimulate those cells. The strategy has already produced evidence that optogenetic therapy could partially restore visual function, although such treatments remain under development and are not yet broadly available.
Scientists are also investigating whether optogenetic principles could improve cochlear implants by allowing more precise stimulation of auditory nerve pathways. Other research is exploring possible applications in neurological and psychiatric disorders.
Despite the excitement surrounding the technology, researchers caution that many of its most ambitious medical applications remain experimental. Much of the ability to manipulate specific neurons with light has been demonstrated in laboratory animals, and translating those techniques safely and effectively into human medicine presents significant technical and biological challenges.
The careers of the three Nobel laureates followed different paths before converging on the discovery that would change neuroscience.
Hegemann, now 71, became fascinated by how organisms sense and respond to their environment. His interest in the movement of algae toward light eventually led him toward the proteins responsible for that behaviour.
Nagel, 73, collaborated with Hegemann to identify and characterize channelrhodopsin. Their experiments established that the light-sensitive protein could produce electrical responses in cells, laying an essential foundation for optogenetics.
Deisseroth, 54, is a professor at Stanford University and an investigator with the Howard Hughes Medical Institute. His interest in the brain was partly shaped by his experience treating patients in a psychiatric clinic while training to become a neurosurgeon. Reuters reported that seeing patients with serious psychiatric conditions for whom doctors had limited tools to help motivated him to investigate the biological mechanisms underlying brain disorders.
The announcement also produced very different reactions from the three scientists. Deisseroth said he received the call from Stockholm while he was still awake late at night, while Hegemann described the news as overwhelming. Nagel said he was sitting on a terrace near Naples when he received the call informing him that he had won.
The Nobel recognition highlights the importance of basic scientific research and the unexpected ways discoveries can move from fundamental biology into advanced medical research. A question about how a microscopic organism responds to light ultimately contributed to the development of a technology capable of manipulating individual nerve cells in a living brain.
Optogenetics has fundamentally changed how scientists study the nervous system. Researchers can now move beyond simply observing brain activity and experimentally test how particular neurons influence memory, emotion, movement and behaviour.
The long-term medical implications remain an active area of research. Scientists are investigating whether the technology can help develop treatments for diseases that currently have limited therapeutic options, while continuing to refine methods for delivering light-sensitive proteins and controlling cells safely.
For the Nobel Committee, the significance of the work lies not only in what optogenetics has already revealed but also in the possibilities it creates for future discoveries.
The 2026 Nobel Prize in Physiology or Medicine therefore recognizes a scientific breakthrough that brought together molecular biology, genetics, optics and neuroscience. What began with the study of light-sensitive proteins in algae has become a powerful method for exploring one of science's greatest remaining mysteries: how billions of interconnected nerve cells produce the memories, feelings and behaviours of a living human being.