Stockholm: American scientist Karl Deisseroth and German scientists Peter Hegemann and Georg Nagel have won the 2026 Nobel Prize in Physiology or Medicine for discoveries concerning light-gated ion channels and optogenetics, a technique that has transformed the study of the brain.
The Nobel Assembly at Karolinska Institutet announced the award on Monday, October 5, recognising work that has made it possible to control the activity of individual nerve cells using light. The three laureates will share the prize money of 12 million Swedish kronor, roughly $1.2 million.
The breakthrough has given neuroscientists a powerful way to study how individual neurons and networks of nerve cells influence behaviour and brain function. Optogenetics allows researchers to switch selected nerve cells on or off with light, providing a level of precision that was previously difficult to achieve.
What is optogenetics?
Optogenetics combines genetics and optical technology to control the activity of specific cells.
The technique relies on light-sensitive proteins known as opsins. These proteins can be introduced into selected nerve cells, where they function as light-controlled switches. When the appropriate light is delivered, the proteins can alter the movement of charged particles across the cell membrane and consequently influence the electrical activity of the neuron.
The Nobel Assembly described optogenetics as a method that makes it possible to switch the activity of individual nerve cells on or off in a living brain. The technique is now used by laboratories around the world to investigate the brain and its complex networks.
The discovery has been particularly valuable because the brain contains billions of interconnected nerve cells. Being able to selectively manipulate particular neurons allows researchers to investigate how specific circuits contribute to movement, memory, emotion and other functions.
Hegemann and Nagel uncover light-sensitive proteins
The story behind the Nobel-winning work began with research into how simple organisms respond to light.
In the early 1990s, Peter Hegemann studied the green alga Chlamydomonas and investigated how it responded to light extremely rapidly. He proposed that a light-sensitive protein could be responsible for detecting light and influencing the movement of ions across a cell membrane.
Georg Nagel subsequently helped test the hypothesis by introducing genes from Chlamydomonas into frog egg cells. Their experiments led to the identification and characterisation of channelrhodopsin-2, a light-gated ion channel.
The discovery provided scientists with a biological mechanism that could translate light into electrical activity in cells.
Hegemann and Nagel later demonstrated that the light-sensitive protein could be introduced into mammalian cells, allowing electrical impulses to be generated in response to light. Their work provided an essential foundation for the development of optogenetics.
Deisseroth turns the discovery into a neuroscience tool
Karl Deisseroth, a psychiatrist and neuroscientist at Stanford University, played a crucial role in bringing the technology into neuroscience.
In 2005, Deisseroth and his colleagues demonstrated that light-sensitive proteins could be used to control the activity of nerve cells. The work showed that researchers could use light to manipulate neural activity with much greater precision than conventional electrical stimulation.
The approach soon became known as optogenetics and developed into an important experimental method in neuroscience.
Researchers could now investigate whether activating or silencing a particular group of neurons produced a specific behaviour or physiological response.
This made it possible to move beyond simply observing brain activity and begin experimentally testing the role of individual neural circuits.
Why the discovery matters for brain research
One of the biggest advantages of optogenetics is its precision.
Traditional methods of stimulating the brain can affect groups of cells or surrounding tissue. Optogenetics can be designed to target specific populations of neurons, allowing scientists to examine their individual contributions to complex brain functions.
The technique has consequently become an important tool in research into neural circuits and neurological disorders.
It has helped scientists investigate questions surrounding how the brain controls behaviour and how particular neural pathways function.
The Nobel Assembly said the discoveries had opened new ways of revealing the mysteries of the brain, highlighting the broad impact of the work on modern neuroscience.
Potential applications in medicine
Although optogenetics has primarily been a research tool, scientists are also investigating potential clinical applications.
One area is the treatment of retinitis pigmentosa, an inherited eye disorder that can cause progressive loss of vision.
Researchers are conducting clinical studies in which light-sensitive proteins are introduced into retinal cells in an attempt to restore some visual function in people who have lost their sight because of the disease.
The technology is also being investigated in connection with hearing. Researchers hope that light-based stimulation could eventually make cochlear implants more precise by allowing more targeted activation of the auditory nerve than conventional electrical stimulation.
These applications remain areas of research, and the Nobel recognition does not mean that optogenetics-based treatments are established therapies for all patients.
Laureates surprised by Nobel recognition
Thomas Perlmann, Secretary-General of the Nobel Assembly at Karolinska Institutet, said he spoke with all three laureates after the announcement.
According to Perlmann, the scientists were surprised and delighted to receive the award together.
The shared recognition also reflects how the development of optogenetics resulted from contributions made at different stages of the research — from identifying light-gated ion channels in algae to adapting the technology for controlling neurons.
The Nobel Assembly’s citation recognises this combined scientific progression rather than a single experiment or discovery.
Nobel medicine prize has a long scientific history
The Nobel Prize in Physiology or Medicine is traditionally the first of the annual Nobel awards to be announced.
The prizes were established through the will of Swedish inventor and industrialist Alfred Nobel, with the original awards first presented in 1901. The economics prize was established separately in 1968 by Sweden’s central bank, the Riksbank.
The medicine prize has previously recognised discoveries that transformed healthcare and biology, including Alexander Fleming’s discovery of penicillin and Karl Landsteiner’s work on human blood groups.
The 2025 Nobel Prize in Physiology or Medicine was awarded to Mary E. Brunkow, Fred Ramsdell and Shimon Sakaguchi for discoveries concerning peripheral immune tolerance and how the immune system is regulated.
Nobel celebrations culminate in December
The announcement of the medicine prize begins the annual Nobel week, with the prizes in physics, chemistry, literature and peace announced over the following days. The economics prize is announced separately.
The formal award ceremonies take place on December 10, the anniversary of Alfred Nobel’s death. The Nobel laureates traditionally receive their medals and diplomas at ceremonies in Stockholm, while the Nobel Peace Prize is presented in Oslo.
For Deisseroth, Hegemann and Nagel, the 2026 medicine prize recognises a scientific journey that began with the study of how algae respond to light and ultimately produced a powerful method for controlling nerve cells.
Their work has changed how scientists investigate the brain and could eventually contribute to new approaches for treating neurological and sensory disorders.