3 Scientists Share Nobel Prize in Physiology or Medicine for Optogenetics

Three scientists who turned a light-sensing protein from pond algae into a switch for nerve cells were awarded the 2026 Nobel Prize in Physiology or Medicine today.

The Nobel Assembly at Karolinska Institutet in Stockholm, Sweden, honored Karl Deisseroth, MD, PhD, of the Howard Hughes Medical Institute and Stanford University; Peter Hegemann, PhD, of Humboldt University of Berlin, Germany; and Georg Nagel, PhD, of the University of Würzburg, Germany, “for their discoveries concerning light-gated ion channels and optogenetics.”¹

“Optogenetics provides opportunities for mapping the brain in a way that we could once only dream of,” Per Svenningsson, chair of the Nobel Committee for Physiology or Medicine, said in a statement.¹

From Association to Cause

Optogenetics lets researchers activate selected neurons with light and observe the result, which makes it possible to show that a circuit causes a behavior rather than merely accompanies it. Earlier methods revealed which brain areas affect which functions but could not prove causal relationships, the Nobel Assembly said.

Laboratories worldwide now use the method to identify the neural circuits governing specific memories, feelings, and behaviors relevant to neurological and psychiatric disorders. In clinical medicine, researchers are using it in attempts to restore sight in people with visual impairment.

How Each Laureate Contributed

The search for a neuronal switch did not start in the brain. Francis Crick suggested in the late 1990s that light might offer the speed and precision needed to control selected neurons, an idea that seemed far-fetched at the time, said Abdel El Manira, a professor of neuroscience and Nobel Committee member who presented the science at the announcement.

The answer came from Chlamydomonas, a single-celled green alga that senses light through a primitive eyespot and swims toward it.

Hegemann. In the 1990s, Hegemann used electrical recordings to show that the eyespot contains a light-sensitive protein that converts light almost instantly into an electrical signal. He then identified the gene for that protein.² His prize-winning work was done at the Max Planck Institute for Biochemistry in Martinsried, Germany; he is now Hertie Senior Professor of Neuroscience at Humboldt University.

Nagel. Then an ion channel specialist at the Max Planck Institute for Biophysics in Frankfurt, Germany, Nagel used Hegemann’s gene to produce the protein in frog egg cells and study its function. In the early 2000s, the pair found that the protein itself is a light-gated ion channel, which they named channelrhodopsin.³ The protein sits on the cell surface. When blue light strikes it, a channel opens through the protein, positively charged ions rush into the cell, and an electrical impulse results. Any cell given the protein became light sensitive.

Today, Nagel is a professor of molecular plant physiology at Würzburg.

Deisseroth. A psychiatrist then starting his laboratory at Stanford, Deisseroth wanted to draw causal links between brain circuits and behavior. He introduced the channelrhodopsin gene into rat nerve cells and showed that blue light triggered a nerve signal on command, with millisecond precision. He published the result in 2005.⁴

Two years later, his team made the switch work in living mice. They placed channelrhodopsin in a selected group of neurons and developed tiny optical fibers to deliver light deep into the brain. Turning on the light activated those neurons and elicited a distinct behavior, such as exploring unfamiliar objects. Deisseroth is the D.H. Chen Professor and a professor of bioengineering and of psychiatry and behavioral sciences at Stanford.

“For the first time, causal links between specific brain circuits and behavior had been achieved,” El Manira said.

Current Research and Therapeutic Uses

Researchers have used optogenetics to tie the activity of specific neuronal populations to complex behaviors, including parental behavior, aggression, anxiety, and fear, and to physiological drives such as thirst, El Manira said. The method has also helped reveal how circuits are disrupted in disease, with implications for blindness, depression, addiction, and dementia.

“Before we had anatomical maps of the brain. Now we can generate functional maps,” Anna Wedell, a Karolinska Institutet professor and adjunct member of the Nobel Committee, said during the press conference.

Much of the work is done in mice that model epilepsy, dementia, depression, or addiction, Wedell said. Investigators can see which nerve cells and circuits are affected and whether modifying other circuits changes how disease presents. “Then we know where to look in humans based on this knowledge,” she said.

Asked by a reporter about therapies, Svenningsson cited retinitis pigmentosa, in which patients lose the rod and cone photoreceptors in the retina. Optogenetics has partially restored vision in blind patients with the disease, he said. Researchers use it to stimulate the healthy cells that remain in the retina, which activate the optic nerve and generate visual perception in the brain.

Patients must wear special goggles that record their surroundings and project the recording as light onto the retina, Svenningsson said. Several clinical trials of the approach are ongoing.

Thomas Perlmann, secretary-general of the Nobel Assembly, called the vision work an excellent example, but said optogenetics is “primarily a tool for basic research that will prove immensely important for disease and understanding of disease.”

Some questions remain out of reach. Asked whether the technique could explain consciousness, El Manira said studies are examining how perception becomes lasting memory. “But we are far from understanding that,” he said.

Sharing the Prize

The prize carries 12 million Swedish kronor, about $1.2 million, to be shared equally. Deisseroth, Hegemann, and Nagel will each receive one-third: 4 million kronor, or about $400,000. Nobel laureates also receive a gold medal and a diploma during a ceremony on December 10.

Perlmann said he reached all 3 laureates by phone before the announcement, waking Deisseroth. All were surprised, he said, and each called it an honor to share the prize with the other 2, whom they described as friends.

References

1. Light-seeking algae gave us a switch for nerve cells. The Nobel Prize. October 5, 2026. Accessed October 5, 2026. https://www.nobelprize.org/prizes/medicine/2026/press-release
2. Harz, Hartmann, and Peter Hegemann. Rhodopsin-regulated ion motility in Chlamydomonas. Nature. 1991;351(6326):489–491.
3. Nagel G, Ollig D, Fuhrmann M, Kateriya S, Musti AM, Bamberg E, Hegemann P. Channelrhodopsin-1: a light-gated proton channel in green algae. Science. 2002 Jun 28;296(5577):2395-8. doi: 10.1126/science.1072068.
4. Boyden ES, Zhang F, Bamberg E, Nagel G, Deisseroth K. Millisecond-timescale, genetically targeted optical control of neural activity. Nat Neurosci. 2005;8(9):1263-1268. doi:10.1038/nn1525.