The Nobel Assembly at Karolinska Institutet announced in a press release that it has awarded the 2026 Nobel Prize in Physiology or Medicine jointly to Karl Deisseroth, MD, PhD, Peter Hegemann, PhD, and Georg Nagel, PhD, for their discoveries concerning light-gated ion channels and optogenetics. Optogenetics is a method that makes it possible to show how nerve cells shape memories, feelings, and behaviors in the living brain. Hegemann and Nagel discovered a protein, channelrhodopsin, in a single-celled alga, and Deisseroth transformed the protein into a light-controlled switch for nerve cells.  

“Optogenetics provides opportunities for mapping the brain in a way that we could once only dream of,” said Per Svenningsson, chair of the Nobel Committee for Physiology or Medicine, in the press release.

Hegemann wondered how Chlamydomonas, a single-celled alga, is able to swim toward a light source. In the early 2000s, he and Nagel discovered channelrhodopsin, an algal protein with unique properties, found on the surface of the cell. When it is illuminated by blue light, a channel opens through the protein. Charged ions then flow into the cell, creating an electrical impulse. They found that regardless of which cell they put the protein in, those cells became light sensitive.

Deisseroth introduced the gene for channelrhodopsin into nerve cells from rats. By illuminating the cells with blue light, he was able to trigger a nerve signal. He published this breakthrough in 2005. Two years later, he made this light-controlled switch for nerve cells work in the brains of living mice.

This method for controlling nerve signals with light is now called optogenetics. Using optogenetics, researchers have been able to reveal neural circuits governing specific memories, feelings, and behaviors relevant for neurological and psychiatric disorders. In clinical medicine, researchers are using the method in attempts to restore sight in people with visual impairment, the press release noted. RP