2026 Nobel Prize for Physiology and Medicine Goes to Optogenetics, Light-Gated Ion Channels

The Nobel Prize in Physiology or Medicine 2026 has been awarded to Karl Deisseroth, MD, PhD, Peter Hegemann, PhD, and Georg Nagel, PhD, for their discoveries of light-gated ion channels and optogenetics.

Deisseroth is a Professor of Bioengineering and of Psychiatry and Behavioral Sciences at Stanford University and an HHMI Investigator; Hegemann is the Hertie Senior Research Chair for Neurosciences and a professor of Experimental Biophysics at Humboldt University and Nagel is a professor at the Department for Neurophysiology at the University of Würzburg, in Germany.

“Optogenetics provides opportunities for mapping the brain in a way that we could once only dream of,” says Per Svenningsson, MD, PhD, Chair of the Nobel Committee for Physiology or Medicine.

Although optogenetics is a relatively new technology, the seminal paper from the Deisseroth lab was published in 2005. However, the concept of manipulating specific neuronal cell types within intact circuits on a millisecond timescale was considered long before. Indeed, Francis Crick, PhD, once proposed a method where “all neurons of just one type could be activated or inactivated, leaving the others more or less unaltered.” He speculated that to “turn the firing of one or more types of neurons on and off in the alert animal in a rapid manner … the ideal signal would be light,” acknowledging at the time that his idea was “rather far-fetched.” In addition, scientists have been working on laying the foundation for this technology since the 1970s. For example, when Richard Fork, PhD, at Bell Laboratories in New Jersey at the time, published the stimulation of neurons in Aplysia with laser light in Science.

It was the discovery of the algal protein channelrhodopsin that led the way in making the vision into a reality. Microbial rhodopsins—found across archaea, eubacteria, and eukaryotic microalgae—harness light for cellular bioenergetics. Channelrhodopsin is found on the surface of Chlamydomonas, a single-celled alga with the ability to swim towards a light source. Researchers discovered that the protein can directly convert photon energy into transmembrane ion flux.

The first direct evidence of a light-gated ion channel was named channelrhodopsin-1 (ChR1), discovered and coined by the Hegemann lab. The arguably more consequential breakthrough came just a year later: a collaborative team led by Georg Nagel, demonstrated that a second protein, named channelrhodopsin-2 (ChR2), functioned distinctly from ChR1, and exhibited a blue-shifted activation spectrum and operated as a broad, non-selective cation channel.

Finding a microbial protein that could act as a single unit, simultaneously as a photoreceptor and an ion channel, and the discovery that ChR1 and ChR2 were single-component, light-gated ion channels, provided the precise tools that neuroscientists had been looking for—for fast, genetically targetable optical activation of neurons.

The team in the Deisseroth lab took the baton and performed the first successful demonstration that ChR2 could be expressed in neurons, using a construct provided by Nagel. They introduced the gene for channel-rhodopsin into nerve cells from rats and was able to trigger a nerve signal by illuminating the cells with blue light.

Deisseroth’s lab published this breakthrough in 2005 in the Nature Neuroscience paper, “Millisecond-timescale, genetically targeted optical control of neural activity.” The study demonstrated that expressing the microbial protein channelrhodopsin-2 (ChR2) from green algae in cultured mammalian neurons allowed precise, millisecond-timescale control of action potentials using flashes of blue light.

The paper’s first author was Ed Boyden, PhD, professor in Neurotechnology at MIT who has been developing the field of optogenetics for the past two decades. Interestingly, CRISPR pioneer Feng Zhang, PhD, is the second author on the 2005 paper. Two years later, Deisseroth’s lab made this light-controlled switch for nerve cells work in the brains of living mice.

Over the past two decades, optogenetics has been used to unpack many biological questions, primarily (but not exclusively) in the field of neuroscience. One early in vivo application of optogenetics probed the causal relationship between the activation of orexin/hypocretin neurons in the lateral hypothalamus and the transitions from sleep to wakefulness. Other notable applications were the search for the memory engram—the physical cellular substrate encoding a specific memory—and unpacking the complexity of dopaminergic neurons in the retina, showing that functionally distinct dopaminergic populations are anatomically intermingled yet strictly segregated by their circuit connectivity.

Optogenetics has also moved into clinical applications, such as the expression of ChR2 in retinal circuitry. In one experiment, intraocular injection of an adeno-associated viral (AAV) vector encoding ChR2 led to expression in retinal ganglion cells in rodents. More specifically, light depolarized the ChR2 expressing retinal ganglion cells, restoring retinal photosensitivity and allowing light signals to reach the visual cortex in a mouse model of retinitis pigmentosa. Expression of ChR2 in surviving retinal neurons could therefore serve as a potential strategy for restoring vision after rod and cone degeneration.

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