2026 Nobel Prize in Physiology or Medicine Awarded For Development of Optogenetics to Control Brain Cells with Light

The 2026 Nobel Prize in Physiology or Medicine has been awarded to American researcher Karl Deisseroth alongside German scientists Peter Hegemann and Georg Nagel for discoveries that led to optogenetics, a breakthrough technique allowing scientists to switch individual brain cells on and off using light.

The three winners will share the prize money of 12 million Swedish crowns (approximately $1.2 million or £900,000).

Announcing the decision on Monday, Thomas Perlmann, Secretary-General of the Nobel Assembly at Karolinska Institutet, stated: "This method makes it possible to switch on, or off, the activity of individual nerve cells in a living brain."

The Nobel Assembly added that the technique has fundamentally changed how researchers view the mind: "Optogenetics has fundamentally altered our understanding of the brain. Every day brings new discoveries, helping to solve one of humanity's greatest mysteries: how our incredible brain works."

Anna Wedell, a genetics professor and member of the Nobel Committee, emphasized the long-term impact on scientific research:

"For the first time we can actually start to understand how the brain processes information and how different neurons interact across the brain,"

From Single-Celled Algae to Frog Eggs: The Breakthrough

The foundation for optogenetics began in the early 1990s when Peter Hegemann investigated how the microscopic green alga Chlamydomonas moves toward light. Hegemann noted that the alga responded to light in just half a millisecond, which is far faster than the complex multi-step chemical reactions found in human eyes.

Hegemann hypothesized that a single protein acted as both a light receptor and an ion channel. To test his theory, he partnered with Georg Nagel, who injected the algal genes into frog eggs. Nagel confirmed the hypothesis, discovering light-activated proteins named channelrhodopsins that opened as ion channels when illuminated.

In 2003, Hegemann and Nagel published findings showing that introducing channelrhodopsin-2 into human and hamster kidney cells allowed light to generate electrical signals inside them.

The discovery caught the attention of Karl Deisseroth, a psychiatrist and neuroscientist at Stanford University who sought clearer answers for patients suffering from psychiatric and neurological conditions.

After obtaining the DNA from Nagel, Deisseroth tested channelrhodopsin-2 in cultured rat nerve cells in 2005, successfully triggering nerve impulses using blue light. The technique was formally named optogenetics in 2006.

By 2007, Deisseroth’s lab succeeded in using thin optical fibers inserted into the brains of live mice to activate motor cortex cells and control whisker movements. In another experiment, shining light on specific neurons woke sleeping mice on command.

In 2012, Deisseroth collaborated with Susumu Tonegawa to reactivate fear-memory neural pathways, known as engrams, in mice, proving which specific cells held a given memory.

Reflecting on the technique's impact, Manuel Valero, head of the Neural Computation Laboratory at Barcelona's Hospital del Mar, said that it has "allowed us to push the boundaries between science and science fiction."

"In laboratory animals, we have managed to control emotions, create false memories or even recover lost memories in models of Alzheimer's disease. Perhaps the great promise it has yet to fulfil is precisely one of its founding promises: its ability to treat diseases of the human brain."

Early Medical Applications and Clinical Trials

Researchers are now using optogenetics to explore conditions such as depression, schizophrenia, Parkinson’s disease, epilepsy, and addiction.

The method is also advancing toward human therapies:

• Sight Restoration: Clinical trials are placing light-sensitive algal proteins into the retinas of patients with retinitis pigmentosa, enabling previously blind individuals to perceive objects when wearing special light-emitting glasses.
• Hearing Enhancements: Scientists are investigating whether optogenetics can replace electrical stimulation in cochlear implants to stimulate auditory nerves with greater precision.

Paul Bresge, CEO of Ray Therapeutics, commented on the potential of retinal treatments:

"When you think about it in the retina, all patients need to do is open their eyes and you have the light…So it makes a lot of sense as a potential therapy."

Reacting to the Award

The winners expressed delight upon receiving the news from Sweden.

Deisseroth, who was awake in the early morning hours, said:

"I was not yet asleep, being a night owl, and now I don't think I'll be able to sleep for quite a while."

Hegemann said: "It's unbelievable when you get this message."

Nagel, who was visiting a village outside Naples when notified, added: "I actually thought it would not happen, but some other people always told me this will happen."

Per Svenningsson, chair of the Nobel Committee, summarized the achievement: "Optogenetics provides opportunities for mapping the brain in a way that we could once only dream of."