Karl Deisseroth won the 2026 Nobel Prize for his work on optogenetics. Here is how his discovery uses light to control nerve cells and study the brain. 

Published on: Oct 5, 2026, 18:11:06 IST

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American scientist Karl Deisseroth has won the 2026 Nobel Prize in Physiology or Medicine along with German scientists Peter Hegemann and Georg Nagel. They were honoured for their work on light-gated ion channels and optogenetics, a method that helps scientists understand how the brain works.

Deisseroth is 54 years old. Hegemann is 71, while Nagel is 73. The Nobel Assembly at Sweden’s Karolinska Institutet chose the three scientists for their work on how light can control nerve cells, Reuters reported.

Their discovery is important because it allows scientists to control individual nerve cells using light. Thomas Perlmann, Secretary-General of the Nobel Assembly at Karolinska Institutet, said optogenetics can turn individual nerve cells in a living brain on or off.

What exactly is optogenetics?

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In simple terms, it is a technique that combines light and genetics to control specific cells. Scientists introduce light-sensitive proteins into nerve cells. When light is directed at those cells, the proteins react and can change the electrical activity of the cells.

This has given scientists a new way to study the brain. Instead of simply observing brain activity, researchers can activate or silence specific nerve cells and then study what happens, according to Reuters.

How algae helped scientists

The story of optogenetics began with research on algae. In the early 1990s, Peter Hegemann studied how the single-celled alga Chlamydomonas responds to light.

Hegemann believed a single protein could be responsible for this rapid reaction. He proposed that the protein could capture light and also work as an ion channel, a type of protein that allows electrically charged particles to move through a cell membrane.

Georg Nagel then helped test this idea. He inserted genes from Chlamydomonas into frog eggs to study the proteins produced by those genes.

What is channelrhodopsin-2?

That research led to the discovery of channelrhodopsin-2. It was found to be an ion channel that opens when exposed to light. This became a key part of the technology that later developed into optogenetics, according to Reuters.

Hegemann and Nagel published another important finding in 2003. They showed that the light-sensitive protein could be introduced into human and hamster cells, where light could then be used to create electrical impulses.

Karl Deisseroth took the discovery into neuroscience. In 2005, Deisseroth, working at Stanford, demonstrated that the technique could be used in rat nerve cells. This showed that light-sensitive proteins could be used to control the activity of neurons. The technique was named “optogenetics” in 2006, one year after Deisseroth's demonstration in rat nerve cells.

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