On 5 October, Karl Deisseroth, Peter Hegemann and Georg Nagel won the 2026 Nobel Prize in Physiology or Medicine. They received the prize for developing a new method called optogenetics. This method lets scientists turn brain cells on or off using light. With this, researchers can study how the brain makes memories and controls the body by shining light on certain nerve cells.

This technology began when Hegemann and Nagel studied a very small, single-celled alga. They discovered a protein called channelrhodopsin. When light shines on the alga, this protein opens and lets small electric charges enter the cell. Later, scientists learned to add the gene for this protein to brain cells in animals. This allowed them to control these cells with light, just like in the alga.

Because of this work, scientists can now look at what happens when they switch on or off specific brain cells. For example, in an experiment in 2012, scientists made mice remember a frightening shock by only shining light into their brains. This helped show how certain brain cells are important for memory.