Nobel medicine prize goes to scientists who learned to control nerve cells with light

Three scientists have won the 2026 Nobel Prize in Physiology or Medicine for discoveries that transformed a light-sensitive protein from algae into a tool for controlling nerve cells, opening a new era in research into the brain, behaviour and neurological and psychiatric disorders.

The Nobel Assembly at Karolinska Institutet announced on October 5 that Karl Deisseroth, Peter Hegemann and Georg Nagel would share the prize “for their discoveries concerning light-gated ion channels and optogenetics”. The three laureates will divide the 12 million Swedish kronor prize equally.

Optogenetics allows researchers to use light to switch the activity of selected nerve cells on or off, making it possible to investigate which cells and neural circuits contribute to particular memories, emotions and behaviours.

From light-sensitive algae to control of nerve cells

The discoveries began with a fundamental question: how does the single-celled alga Chlamydomonas sense light and swim towards it?

In the early 2000s, Hegemann and Nagel identified channelrhodopsin, a light-sensitive protein in the alga. When exposed to blue light, the protein opens an ion channel in the cell membrane, allowing electrically charged ions to flow through and generate an electrical signal.

Crucially, the researchers showed that the protein could also make other cells respond to light when introduced into them, providing the foundation for using light to control cellular activity.

Deisseroth then adapted the discovery for neuroscience. His team introduced the gene encoding channelrhodopsin into nerve cells and showed in 2005 that flashes of blue light could trigger neuronal activity. The approach was subsequently extended to nerve cells in living animals.

The combination of genetic modification and light to precisely control selected cells became known as optogenetics.

Technique reveals how brain circuits influence behaviour

Before optogenetics, scientists could identify brain regions associated with particular functions, but demonstrating cause and effect at the level of specific groups of nerve cells was much more difficult.

The technique allows researchers to selectively activate or suppress targeted neurons and then observe changes in behaviour, movement or other physiological responses.

It has helped scientists identify neural circuits involved in memory, emotion and specific behaviours, while also investigating circuits that are disrupted in neurological and psychiatric conditions.

The technology has therefore provided researchers with new ways to identify potential targets for future treatments. However, the ability to control nerve cells with light in laboratory research does not mean that light-based treatment for brain disorders is already available for routine clinical use.

Optogenetics tested in efforts to restore sight

One area where optogenetics has already moved into human research is the attempt to restore vision in people with severe retinal disease.

In 2021, researchers reported that an optogenetic treatment produced a partial recovery of visual function in a patient with advanced retinitis pigmentosa.

The approach used gene therapy to make surviving retinal cells sensitive to light, combined with specially engineered goggles that projected visual information onto the retina. During testing, the patient was able to locate, count and reach for objects while using the goggles.

The result represented an early proof of concept rather than a restoration of normal sight, and further research is required before the technique could be used more widely.

Three scientists behind the breakthrough

Karl Deisseroth, born in 1971, is a professor of bioengineering and of psychiatry and behavioural sciences at Stanford University and an investigator at the Howard Hughes Medical Institute in the United States.

Peter Hegemann, born in 1954, is based at Humboldt University of Berlin, where his work focuses on experimental biophysics and neuroscience. His prize-winning research on channelrhodopsins began while he was working at the Max Planck Institute of Biochemistry in Martinsried, Germany.

Georg Nagel, born in 1953, is a professor at the University of Würzburg in Germany. His work contributing to the discovery of light-gated ion channels was carried out while he was at the Max Planck Institute for Biophysics in Frankfurt.

The Nobel Assembly said the discoveries had laid the foundation for a new era in neuroscience, giving scientists a way to test directly how specific nerve cells shape activity in the living brain.

Source: Karolinska Institutet News