As of about 12:20 p.m. EDT Monday, Oct. 5, 2026, the Nobel Assembly at Karolinska Institutet announced Monday that it has awarded the 2026 Nobel Prize in Physiology or Medicine jointly to Karl Deisseroth, Peter Hegemann and Georg Nagel “for their discoveries concerning light-gated ion channels and optogenetics.”
The prize recognizes a method that uses light to switch individual nerve cells on or off in a living brain. The Nobel Committee’s own account traces it to a question about how a single-celled alga reacts to light.
Who won, and where they work
According to the Nobel Assembly’s press release, the three laureates are:
- Karl Deisseroth, born 1971, of the Howard Hughes Medical Institute and Stanford University, USA. He holds a Ph.D. (1998) and an MD (2000) from Stanford.
- Peter Hegemann, born 1954, of Humboldt University of Berlin, Germany. The Committee says the prize-awarded discoveries were made at the Max Planck Institute for Biochemistry in Martinsried, Germany.
- Georg Nagel, born 1953, of the University of Würzburg, Germany. The Committee says his prize-awarded discoveries were made at the Max Planck Institute for Biophysics in Frankfurt, Germany.
The press release divides the roles in one sentence: “Peter Hegemann and Georg Nagel discovered a remarkable protein, channelrhodopsin, in a single-celled alga. Karl Deisseroth transformed the protein into a light-controlled switch for nerve cells.”
The prize amount is 12 million Swedish kronor, to be shared equally between the laureates.
What optogenetics is, in plain words
The Committee describes optogenetics as a method that “makes it possible to switch on, or off, the activity of individual nerve cells in a living brain.”
STAT, which reported the announcement the same day, summarizes it as a method that “uses light, combined with genetic modifications of neurons.” In practice, as the Committee tells it, researchers put the gene for a light-sensitive protein into a chosen type of nerve cell. When light reaches that cell, the protein opens a channel in its surface. Charged particles flow through, and the cell produces an electrical signal.
The Committee defines an ion channel as “an opening in the cell surface through which charged ions can flow, creating an electrical signal.”
The Committee says the older methods of the 20th century “could not prove that a specific type of nerve cell directly caused a certain feeling or behaviour.” It compares the resulting picture of the brain to “a blurry photograph, missing many details.”
Per Svenningsson, Chair of the Nobel Committee for Physiology or Medicine, said: “Optogenetics provides opportunities for mapping the brain in a way that we could once only dream of.”
How the discovery unfolded
The Committee’s popular information describes the sequence this way.
- Early 1990s. At the Max Planck Institute for Biochemistry in Martinsried, Hegemann asked how the alga Chlamydomonas can react so rapidly to light.
- The alga’s speed. Using tiny electrodes, he measured an electrical impulse just half a millisecond after light reached the alga’s eyespot. The Committee gives no year for the measurement. It notes that the process in a human eye “takes at least 10 milliseconds,” so the alga’s response was “more than twenty times faster.”
- Early 1990s hypothesis. Hegemann proposed that a single protein complex both captured light and acted as an ion channel. The Committee says the proposal “was met with scepticism,” because researchers knew of no ion channel that reacted to light on its own.
- Around the turn of the millennium. After years of setbacks isolating the protein, the group used the alga’s DNA, mapped by Japanese researchers. They found two genes similar to known genes for light-capturing proteins. Hegemann contacted Nagel, who was then at the Max Planck Institute for Biophysics in Frankfurt.
- Frog eggs. Nagel injected the two genes, separately, into frog egg cells. The Committee says the resulting proteins were ion channels that opened when exposed to light. They were named channelrhodopsin-1 and channelrhodopsin-2. Channelrhodopsin-2 opened a channel within 0.2 milliseconds.
- Human and hamster cells. When the gene for channelrhodopsin-2 was introduced into embryonic human kidney cells and hamster kidney cells, the cells became light-sensitive.
- 2003. Hegemann and Nagel published the results and proposed that channelrhodopsin-2 could be used as a powerful tool to generate electrical impulses in cells using light.
- Nerve cells. Deisseroth, who had started his own research group at Stanford, wrote to Nagel to ask for the DNA. He introduced it into rat nerve cells in petri dishes. When exposed to blue light, the cells produced a nerve signal that could pass to other nerve cells. The popular information says that in 2005, “Deisseroth’s research group published their discovery.”
- 2006. The method was given the name optogenetics.
- 2007. Deisseroth’s group activated nerve cells in the brains of living mice. They introduced the gene into a specific cell type in the motor cortex and lit the cells through a thin optic fibre fed through a small hole in the skull, which let them control movements of the mouse whiskers. The same year, the Committee says, a collaboration used the method to wake sleeping mice.
- 2012. With Susumu Tonegawa, Deisseroth activated an engram in mice, which the Committee defines as “the specific pattern of neural pathways that is formed when a memory is created.” The Committee calls it “the first experiment in which researchers could demonstrate exactly which nerve cells are necessary for a specific memory.”
The press release dates the Hegemann and Nagel discovery to “the early 2000s.” The Committee’s list of key publications gives 2002 for channelrhodopsin-1 and 2003 for channelrhodopsin-2.
What researchers have learned with it
The Committee says an adult human brain has around 90 billion nerve cells, each of which forms thousands of connections with other nerve cells.
The Committee’s examples of these findings mostly refer to mice. According to the Committee, optogenetics has let researchers identify:
- neural circuits that govern “the sense of pain, social behaviours, thirst, food consumption, reward and attention”;
- nerve cells responsible for functions “from controlling the circadian rhythm to causing a fever when the immune system is activated”;
- separate circuits for different parts of a complex behaviour. When researchers studied how mice care for their young, one circuit governed how mice gather their young in a nest and another regulated grooming.
The Committee adds that the method can map the nervous system and cell functions outside the brain. It says “Deisseroth has demonstrated that heart rhythm can affect our emotions; if the heart is forced to work harder, this can reinforce feelings of anxiety.” It also says other researchers have identified specific cells in the gut that can explain why some people would rather eat sugar than sweeteners.
What the Committee says about treatments
The Committee writes that the hope that knowledge from optogenetics will lead to new medical treatments “has begun to come to fruition.” It says the method “has provided greater understanding of the distinguishing features of psychiatric and neurological disorders such as depression, anxiety, schizophrenia, Alzheimer’s disease and Parkinson’s disease.”
It separates understanding from treatment. It says researchers “have also taken the first steps towards using optogenetics as a medical treatment.” STAT likewise says the method “is being studied as a treatment for disease.”
- Blindness. The Committee writes: “In ongoing clinical trials they attempt to restore vision in people who have become blind due to retinitis pigmentosa,” a disease it describes as one that destroys the eye’s rods and cones. It also writes: “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.”
- Hearing. “There are also hopes that optogenetics could improve cochlea implants.” This is a hope, not a result. The Committee explains that current implants stimulate the auditory nerve with electricity, and that optogenetics might allow more precise activation.
The Committee does not name the trials or their sponsors in this text, and gives no further details beyond the passages quoted above. This article does not offer medical advice and does not suggest optogenetics treats any condition today.
The Committee’s key publications
The Committee’s list of key publications includes:
- Harz, Nonnengasser and Hegemann, 1992, Philosophical Transactions of the Royal Society B, on the photoreceptor current of the green alga Chlamydomonas.
- Nagel and colleagues, 2002, Science, on channelrhodopsin-1. Co-authors include Ernst Bamberg and Peter Hegemann.
- Nagel and colleagues, 2003, Proceedings of the National Academy of Sciences, on channelrhodopsin-2. Authors include Bamberg and Hegemann.
- Boyden, Zhang, Bamberg, Nagel and Deisseroth, 2005, Nature Neuroscience, on millisecond-timescale, genetically targeted optical control of neural activity.
- Aravanis and colleagues, 2007, Journal of Neural Engineering, on controlling rodent motor cortex with integrated fiberoptic and optogenetic technology. Deisseroth is the last author.
What we did not find
The three pages we read (the Nobel press release, the Committee’s popular information and the opening of STAT’s report) do not quote the laureates, and we did not read statements from HHMI, Stanford, the Max Planck institutes, Humboldt University or the University of Würzburg.