Scientists win 2026 Nobel Prize for controlling brain cells with light
A discovery in tiny algae led to a Nobel Prize-winning breakthrough that allows scientists to switch brain cells on and off using light. The revolutionary technique has already helped researchers activate memories and is opening new possibilities for restoring vision and treating brain disorders.
Key points
- Karl Deisseroth, Peter Hegemann and Georg Nagel won the Nobel prize in physiology or medicine for optogenetics.
- They found channelrhodopsin, a light-sensitive protein, in the single-celled alga Chlamydomonas.
- Optogenetics lets scientists switch specific nerve cells on and off with light, and is in early trials for retinal degeneration.
Karl Deisseroth, Peter Hegemann and Georg Nagel have won this year's Nobel prize in physiology or medicine for research into "light-gated ion channels and optogenetics," the method of controlling brain cells with light.
Hegemann, at Humboldt University of Berlin, and Nagel, at the University of Würzburg, began by studying how the single-celled alga Chlamydomonas senses light. Deisseroth is a psychiatrist and bioengineer at Stanford University in California.
How the light switch works
Hegemann and Nagel found that the alga detects light through a single protein, channelrhodopsin, built into its outer membrane. The protein holds a small molecule called retinaldehyde, which absorbs light; when light hits it, the protein changes shape and opens a passage that lets positively charged particles, including sodium, flow into the cell and help the alga swim.
Nerve cells also use the movement of charged particles, or ions, to control their activity. The researchers realised that putting channelrhodopsin into nerve cells could let them switch those cells on with light. The gene is usually delivered by a virus altered so it cannot cause disease, and light can be aimed at a small part of the brain through a thin optical fibre.
light-gated ion channels and optogenetics
— the Nobel prize citation
Experiments and medical hopes
In a 2012 experiment, a team at the Massachusetts Institute of Technology gave mice a mild electric shock in a particular cage and tagged the nerve cells active during the fear conditioning. Days later, in a different cage, light switched those cells on and the mice froze in fear, while mice that were not shocked did not. Deisseroth was one of the study's authors.
Optogenetics is already in early-stage clinical trials for people with retinal degeneration, where light-sensitive proteins are introduced into nerve cells that remain in the retina after rods and cones are lost. Researchers are also investigating whether it could eventually treat neurological conditions including Parkinson's and epilepsy.
