Three scientists win Nobel Prize in Medicine

Three scientists have jointly won the 2026 Nobel Prize in Physiology or Medicine for discoveries concerning light-gated ion channels and optogenetics, a technique that allows researchers to control individual nerve cells with light.

The laureates are American scientist Karl Deisseroth and German scientists Peter Hegemann and Georg Nagel. The Nobel Assembly at Sweden’s Karolinska Institutet announced the award on Monday (October 5).

Their work has transformed neuroscience by making it possible to switch nerve cells on or off with pulses of light and observe how specific brain circuits influence memories, emotions and behaviour. The technique has also opened new avenues for studying neurological and psychiatric disorders.

The research began with Hegemann’s efforts to understand how the single-celled alga 'Chlamydomonas' moves towards light. Hegemann and Nagel later discovered channelrhodopsin, a light-sensitive protein in the alga. When exposed to blue light, the protein opens a channel through which charged ions enter the cell, generating an electrical signal.

Deisseroth subsequently introduced the gene responsible for channelrhodopsin into nerve cells. In 2005, he demonstrated that blue light could trigger nerve signals in these cells, and in 2007 he successfully used the technique to control nerve cells in the brains of living mice. This approach became known as optogenetics.

Optogenetics is now widely used in neuroscience research to map neural circuits and investigate how the brain controls behaviour. Researchers are also exploring its potential in clinical medicine, including efforts to restore sight in people with visual impairment.