Karl Deisseroth, Peter Hegemann and Georg Nagel have jointly won the 2026 Nobel Prize in Physiology or Medicine for discoveries that enabled scientists to control nerve cells using light. The Nobel Assembly at Karolinska Institutet awarded the prize on 5 October “for their discoveries concerning light-gated ion channels and optogenetics.” The SEK 12 million ($1.21 million) prize will be shared equally among the three scientists.
Dr Hegemann, of Humboldt University of Berlin, and Dr Nagel, of the University of Würzburg, both in Germany, discovered channelrhodopsins – proteins found in single-celled algae that open ion channels when exposed to light. In particular, channelrhodopsin-2 (ChR2) could be activated by blue light, allowing charged ions to flow across a cell membrane. Dr Deisseroth, of Stanford University and the Howard Hughes Medical Institute, US, subsequently adapted the proteins to control neuronal activity.
The work has transformed neuroscience by allowing researchers to move beyond observing associations between brain activity and behaviour to directly testing causal relationships. “Optogenetics provides opportunities for mapping the brain in a way that we could once only dream of,” said Per Svenningsson, chair of the Nobel Committee for Physiology or Medicine.
The discoveries originated in research into how the green alga Chlamydomonas moves towards light. Hegemann was investigating the organism’s unusually rapid response to illumination when he and colleagues proposed that its light receptor and ion channel might be directly connected.
Unlike earlier approaches for making cells responsive to light, channelrhodopsins offered a genetically encoded, single-protein system capable of producing rapid electrical responses. This made them particularly suited to controlling neurons, whose activity occurs on a millisecond timescale.
The resulting technique, termed optogenetics, has since become a major tool for investigating neural circuits involved in cognition, emotion and behaviour. Researchers have used it to investigate memory engrams, sleep and wakefulness, reward and aversion, anxiety, social behaviour and movement.
Optogenetics has also enabled researchers to distinguish between neighbouring populations of neurons that may have very different functions, helping to establish that complex behaviours are often assembled from multiple specialised neural circuits rather than controlled by individual brain regions as a whole.
The technology has additionally moved towards clinical applications. Researchers have used viral vectors to introduce light-sensitive proteins into surviving retinal cells in people with retinitis pigmentosa, with early clinical studies demonstrating partial restoration of visual function. Several optogenetic approaches to vision restoration are currently being investigated.
The Nobel Committee said the discoveries had fulfilled a long-standing vision in neuroscience of being able to selectively activate or inhibit defined populations of neurons with high spatial and temporal precision. Together, the winners’ work has established optogenetics as a foundational technology for modern neuroscience, providing researchers with a means to “write” into neural circuits as well as observe them.
- By Rosie Bannister
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