The 2026 Nobel Prize in Physiology or Medicine has been awarded to American scientist Karl Deisseroth and German researchers Peter Hegemann and Georg Nagel for discoveries that gave scientists a new way to control nerve cells using light.
The Nobel Assembly at Karolinska Institutet announced the award in Stockholm on Monday, recognising the three scientists for their work on light-gated ion channels and the development of optogenetics, a technique that allows researchers to activate or silence selected nerve cells with precisely controlled light.
The discovery has transformed the way scientists investigate the brain. Instead of observing neural activity without directly controlling it, researchers can now target specific groups of nerve cells and examine how they affect memory, emotions, movement and behaviour.
“Optogenetics provides opportunities for mapping the brain in a way that we could once only dream of,” said Per Svenningsson, chair of the Nobel Committee.
The work has its roots in research on Chlamydomonas, a single-celled alga that responds to light. Hegemann studied how the organism senses changes in light, while further research by Hegemann and Nagel helped identify channelrhodopsin, a light-sensitive protein that forms an ion channel when exposed to light.
The significance of the finding became clearer when the researchers showed that the protein could be introduced into other cells, making them responsive to light. That opened the possibility of using light as a tool to control biological activity in cells that would not normally respond to it.
Deisseroth later brought the technique into neuroscience at Stanford University. In 2005, he demonstrated that introducing the gene responsible for channelrhodopsin into rat nerve cells made it possible to trigger electrical activity in those cells with blue light. Further experiments showed that the approach could also be used in living mice.
That advance gave neuroscientists a powerful way to study the relationship between individual neural circuits and behaviour. Researchers can target particular groups of cells and observe what happens when those circuits are activated or suppressed, helping them investigate how the brain processes information and produces responses.
Optogenetics is now used in research into neural circuits linked to memory, behaviour and a range of neurological and psychiatric conditions. Its value lies partly in the precision it offers. Researchers can manipulate specific cells at specific times, something that is difficult to achieve with many conventional methods for studying the brain.
The technique has also begun moving beyond laboratory research. Clinical trials have explored optogenetic approaches in people with retinitis pigmentosa, an inherited eye disease that causes the loss of light-sensitive cells in the retina. These studies are part of wider efforts to determine whether technologies developed through basic neuroscience can eventually be adapted for medical treatment.
The Nobel Assembly said the researchers’ discoveries have given scientists tools to investigate how individual neural circuits influence memories, feelings and behaviour. The work has also helped establish optogenetics as an important method for examining the complex networks that make up the brain.
Deisseroth, 54, is a professor at Stanford University and an investigator with the Howard Hughes Medical Institute. Hegemann, 71, is affiliated with Humboldt University of Berlin, while Nagel, 73, is based at the University of Würzburg.
The three laureates will share prize money of 12 million Swedish kronor.
The medicine award opens this year’s series of Nobel announcements. The prizes in physics and chemistry will follow on Tuesday and Wednesday, while the literature and peace prizes are scheduled for later in the week. The prize in economic sciences will be announced the following Monday.
The laureates will formally receive their awards on 10 December, the anniversary of Alfred Nobel’s death. For the three scientists recognised this year, the ceremony will mark the culmination of research that began with a basic question about how a tiny organism senses light and ultimately produced a powerful tool for investigating the human brain.
