Scientists are exploring new treatment possibilities for blindness and brain disorders following a Nobel-winning discovery that allows selected nerve cells to be switched on or off using light.

Karl Deisseroth of Stanford University in the United States; Peter Hegemann of Humboldt University of Berlin; and Georg Nagel of the University of Würzburg in Germany won the 2026 Nobel Prize in Physiology or Medicine on Monday for discoveries concerning light-gated ion channels and optogenetics.

The Nobel Assembly at the Karolinska Institutet said the scientists had laid the foundation for a method that enables researchers to control nerve cells using light, providing a more precise way to study individual nerve cells and brain circuits.

The breakthrough has transformed neuroscience by allowing scientists to investigate whether specific groups of nerve cells are directly responsible for particular functions or behaviours. Researchers have used the technique to study brain circuits linked to memory, emotions and behaviour, as well as conditions including depression, schizophrenia and Alzheimer’s disease.

The discovery originated from studies of Chlamydomonas, a single-celled green alga that moves towards light. Hegemann and Nagel identified light-sensitive proteins known as channelrhodopsins in the organism.

When exposed to blue light, the proteins allow charged particles to pass through the cell, producing an electrical signal. Researchers later discovered that the proteins could make other cells respond to light.

Deisseroth and his colleagues took the next major step by introducing the gene responsible for one of these proteins into nerve cells. This enabled the cells to be activated with light and laid the foundation for optogenetics as a major neuroscience research tool.