The Nobel Assembly at Karolinska Institutet announced on Monday morning, 5 October 2026, that the Nobel Prize in Physiology or Medicine had been awarded to scientists Karl Deisseroth, Peter Hegemann and Georg Nagel for their discoveries concerning light-gated ion channels and optogenetics, which laid the foundations for a technique that enables nerve-cell activity to be controlled using light.
The three scientists’ research paved the way for tools capable of activating genetically modified nerve cells with flashes of light, within a timescale matching the cells’ natural response speed.
The technique relies on light-sensitive proteins that can open ion channels, causing charged ions to flow into the cell and generate electrical impulses that trigger an action potential, prompting the cell to respond and transmit information along the axon.
Karl Deisseroth’s role in establishing optogenetics
Karl Deisseroth is a professor of bioengineering, psychiatry and behavioural sciences at Stanford University in California, as well as a researcher at the Howard Hughes Institute. He earned a bachelor’s degree in biochemistry from Harvard University in 1992, followed by a doctorate in neuroscience from Stanford University in 1998.
A major milestone in Deisseroth’s research came in 2005, when he and his colleagues genetically modified nerve cells taken from rats by introducing a light-sensitive gene isolated from pond algae. Experiments showed that flashes of blue light could stimulate the nerve cells, which responded at their natural speed of no more than a few fractions of a second.
Two years later, Deisseroth succeeded in activating the same light-control switch inside nerve cells in the brains of live rats. The significance of the result lay in the ability to stimulate a single protein precisely and within a timescale compatible with nerve-cell function, giving the method an advantage over other techniques available at the time.
Deisseroth has continued his research into optogenetics and its applications ever since. The Nobel Committee said he deserved the award for his efforts to turn the light-sensitive protein into a master switch through which nerve cells can be controlled with light. Between 2002 and 2025, Deisseroth received dozens of awards and honours from international scientific institutions for his role in establishing and developing optogenetics.
His most prominent honours include the Breakthrough Prize in Life Sciences, the Japan-based Kyoto Prize in 2018, the Lasker Award for Basic Medical Research in 2021, the Louisa Gross Horwitz Prize awarded by Columbia University in 2022, the Japan Prize in Life Sciences in 2023, and South Korea’s Asan Award in Basic Sciences in 2025.
Peter Hegemann and the discovery of light-sensitive channels
Peter Hegemann earned a bachelor’s degree in chemistry from the University of Münster in 1975, followed by a doctorate in chemistry from Ludwig Maximilian University in Germany in 1994. He is a Hertie Senior Professor of Neuroscience at Humboldt University of Berlin, an honorary academic rank awarded to a faculty member after retirement from continuous academic work, and heads the Experimental Biophysics Research Group.
Hegemann is regarded as one of the founding fathers of optogenetics. His joint research with Georg Nagel into photoreceptors in single-celled algae known as Chlamydomonas led to the discovery of light-sensitive ion channels inside cells.
Identifying the protein channelrhodopsin-2 made it possible to control genetically modified nerve cells precisely when they were exposed to flashes of light, opening new possibilities for studying neurological diseases and potential treatments.
Hegemann has received several awards for his achievements in this field, including the Mandel Medal from the German National Academy of Sciences Leopoldina in 2017, the Rumford Prize from the American Academy of Arts and Sciences in 2018, the Shaw Prize from Hong Kong, China, in 2020, the Lasker Award for Basic Medical Research in the United States in 2021, and the Louisa Gross Horwitz Prize from Columbia University in 2022.
Georg Nagel’s role in identifying rhodopsin proteins
The third laureate, Georg Nagel, was born in 1953 in Weingarten, Germany. He studied biology and biophysics at the University of Konstanz and received his doctorate from the University of Frankfurt in 1988. He is currently a professor in the Department of Neuroscience at the University of Würzburg.
Nagel received the Karl Heinz Beckurts Prize in Germany in 2010 and, in the same year, the Wiley Prize in Biomedical Sciences in the United States for his role in discovering rhodopsin ion channels. He received the Rumford Prize from the American Academy of Arts and Sciences in Cambridge, United States, in 2019, and the University of Würzburg, where he works, awarded him the Röntgen Medal for his scientific achievements.
At the beginning of the 2000s, Hegemann and Nagel discovered the channelrhodopsin protein on the surfaces of cells of the Chlamydomonas algae. Hegemann had been drawn to the algae’s movement towards light in their environment before the two researchers showed that the proteins they had discovered could respond to light in any cell into which they were placed.
When exposed to flashes of blue light, the ion channels in these proteins open, allowing charged ions to flow into the cell. This produces electrical impulses that trigger an action potential, prompting the cell to respond and begin transmitting information along the axon. The discovery formed the scientific basis for the precise optical-control tools for nerve cells that were developed later.
Optogenetics expands understanding of the brain and its diseases
The Nobel Committee described the three scientists’ achievement as a major transformation that makes it possible to study how memories, emotions and behaviours are formed inside the living brain, after much of its workings had remained mysterious for years. Thanks to optogenetics, it has become possible to identify specialised locations in the brain linked to processes that were previously only a scientific aspiration to reach.
The committee said the technique would change and deepen how the brain is understood because it gives researchers a way to link the activity of particular cells to specific functions and behaviours. Related research is also paving the way for more advanced discoveries in the study of diseases and their treatment, drawing on the ability to activate or control nerve cells with light at high speed and temporal precision.
