Nobel Prize in medicine goes to scientists who learned to switch brain cells on with light

Three scientists who figured out how to turn individual brain cells on and off with a flash of light won the 2026 Nobel Prize in Physiology or Medicine on Monday.

The prize went to Karl Deisseroth of Stanford University and the Howard Hughes Medical Institute, Peter Hegemann of Humboldt University in Berlin and Georg Nagel of the University of Würzburg in Germany, according to STAT News. Reuters reported that the Nobel Assembly honored them "for their discoveries concerning light-gated ion channels and optogenetics."

The award comes with 12 million Swedish crowns, about $1.2 million, to be shared among the three winners, Reuters reported. Deisseroth is American, and Hegemann and Nagel are German.

## What they discovered

The story starts with algae. Hegemann and Nagel discovered channelrhodopsin, a protein in green algae that reacts to light, according to STAT.

Deisseroth then took the gene for that protein and put it into the nerve cells of rats. Once the cells carried the protein, researchers could make them fire simply by shining blue light on them, STAT reported.

## What optogenetics is

The method is called optogenetics, a mix of "optics" (light) and "genetics." It combines light with genetic changes to brain cells so scientists can switch specific cells on or off and watch what happens.

According to the Nobel committee, as quoted by Reuters, optogenetics "makes it possible to switch on, or off, the activity of individual nerve cells in a living brain."

Before tools like this, brain researchers mostly could only observe activity or use blunt methods that affected many cells at once. Optogenetics gives them a way to test which specific cells are involved in a given behavior, by turning those cells on or off and watching the result.

## Why it matters

The technique is now used in laboratories around the world to study how the brain works, Reuters reported. STAT said it helps researchers see how nerve cells shape memories, emotions and behavior.

The method also "is being studied as a treatment for disease," according to STAT, which said it "provides opportunities for mapping the brain in a way that we could once only dream of."

## What happens next

The medicine prize traditionally opens Nobel week, Reuters noted. The prizes in physics, chemistry, literature, peace and economics will be announced over the coming days.

For students thinking about science careers, the prize is a reminder that basic research on something as obscure as pond algae can end up transforming how we study the human brain.