Nobel Prize in Physiology or Medicine 2026 announced: What is optogenetics?

Karl Deisseroth, Peter Hegemann, and Georg Nagel were named winners of the 2026 Nobel Prize in Physiology or Medicine for their discoveries concerning light-gated ion channels and optogenetics. In simple words, the trio's discoveries led to optogenetics, a biological technique that uses light to precisely control the activity of specific cells. It makes it possible to switch the activity of individual nerve cells in a living brain on or off using light.

It all started with the fascination with the 1.3-kilogram organ, which held memories from various stages of our lives, was the reason for daydreaming, drove creative and analytical thinking, and, at the same time, was also what made us feel joy, sadness, love, jealousy and a whole gamut of emotions.

While scientists have known which regions of the brain govern various physiological functions since the early 20th century, they hadn't been able to tell which specific type of nerve cell directly caused a certain feeling or behaviour.

Also Read: Karl Deisseroth, Peter Hegemann and Georg Nagel win Nobel Prize in Medicine for ‘optogenetics’

Activating individual nerve cells in the brain

Francis Crick, who won the Nobel Prize in 1962, started investigating what was behind human consciousness. He wanted to activate individual nerve cells in a living brain, which was hard to do since the signals in nerve cells are extremely rapid. He theorised that if nerve cells could be manipulated to react to light, scientists might be able to control neural activity.

This is what Deisseroth, Hegemann and Nagel achieved. As described on the Nobel Prize website, they were awarded the 2026 prize "for their discovery of a molecular switch for nerve cells. Using light, researchers are now able to switch individual neural circuits on or off in the brain." Their work can “bring memories to life, create feelings, drive behaviours and study the types of neurons that are involved in various psychiatric and neurological disorders.”

How the three contributed to optogenetics

Peter Hegemann & Georg Nagel discovered and characterised channelrhodopsin-2, a light-sensitive ion channel protein present in the eyespot of the unicellular green alga Chlamydomonas reinhardtii. This helped them demonstrate that expressing this single protein in host cell membranes allows the cells to become directly activated and produce electrical signals when exposed to light.

Karl Deisseroth successfully transferred the genetic code for channelrhodopsin-2 into nerve cells, or neurons. He developed this technology into optogenetics, which showed that when blue light is passed through optical fibres, it can selectively trigger electrical activity and control neural circuits in living brains.