Nobel Prize for the scientists who control the brain with light

The 2026 Nobel Prize in Physiology or Medicine has been awarded to three scientists whose discoveries made it possible to switch individual brain cells on and off using light.

Karl Deisseroth, Peter Hegemann and Georg Nagel share the prize "for their discoveries concerning light-gated ion channels and optogenetics". It was announced at the Nobel Forum at the Karolinska Institute in Stockholm on Monday.

The laureates

Karl Deisseroth, 55, is a professor at Stanford University and a Howard Hughes Medical Institute investigator in the United States, as well as a practising psychiatrist. Peter Hegemann, 72, is a professor at the Humboldt University of Berlin, and Georg Nagel, 73, is a professor at the University of Wurzburg in Germany.

They will share the prize of 12 million Swedish kronor, about 1.2 million dollars.

From algae to the brain

The story begins with green algae. Single-celled algae called Chlamydomonas swim towards light using a light-sensitive "eyespot". Working in Germany, Hegemann and Nagel discovered the protein responsible, called channelrhodopsin. When light shines on it, the protein opens a channel in the cell's membrane that allows charged particles, or ions, to flow through.

They found that the protein worked when inserted into other kinds of cells. Deisseroth then introduced the gene for channelrhodopsin into nerve cells from rats, and showed that shining blue light on them could trigger nerve signals. That made it possible to control specific neurons in a living brain with great precision.

"We're using light to turn cells on or off with that millisecond precision and the cellular resolution that is essential to brain function," Deisseroth said.

What optogenetics has done

Optogenetics has become one of the most important tools in neuroscience. Researchers around the world use it to work out which brain cells and circuits control behaviours such as movement, memory, sleep, fear, reward and motivation. It has helped scientists study conditions including Parkinson's disease, addiction, anxiety and depression.

Per Svenningsson, chair of the Nobel Committee, said: "Optogenetics provides opportunities for mapping the brain in a way that we could once only dream of."

Researchers are also exploring medical uses. In early trials, light-sensitive proteins have been introduced into the eyes of people with inherited blindness, helping some to partially regain the ability to detect objects.

Friends and collaborators

All three laureates said they were delighted to share the award. Deisseroth described the others as friends, noting that they had written several papers together.

Research in Birmingham

Neuroscientists at the University of Birmingham and Aston University investigate how the brain works and what goes wrong in neurological and psychiatric conditions, and discoveries like optogenetics have changed the tools available to researchers everywhere.

The rest of Nobel week

The Nobel Prize in Physics will be announced on Tuesday, followed by chemistry on Wednesday, literature on Thursday, the Peace Prize on Friday and the economics prize on Monday 12 October. The prizes will be presented in Stockholm and Oslo on 10 December, the anniversary of Alfred Nobel's death.

Who chooses the winners

The prize in physiology or medicine is chosen by the Nobel Assembly at the Karolinska Institute, a group of 50 professors. Nominations are kept secret for 50 years. Laureates are usually told by telephone shortly before the public announcement, often waking them in the middle of the night if they live in the Americas.