The 2026 Nobel Prize in Physiology or Medicine has been awarded to Karl Deisseroth, Peter Hegemann and Georg Nagel for discoveries involving light-controlled ion channels and the development of optogenetics, a technology that has significantly advanced the study of the brain.
The Nobel Assembly at Karolinska Institutet in Stockholm announced the award on Monday.
Understanding how the brain produces memories, emotions and behaviour has been a longstanding challenge for scientists. Optogenetics has provided researchers with a way to control the activity of selected nerve cells using light, allowing individual neural circuits to be studied in living brains.
“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.
DISCOVERY OF CHANNELRHODOPSIN
The research behind the breakthrough began with studies of microorganisms that respond to light.
Peter Hegemann and Georg Nagel discovered and characterised channelrhodopsin, a light-sensitive protein. Their work showed that cells containing the protein could respond to light by allowing ions to pass through their membranes.
The discovery provided researchers with a mechanism for controlling electrical activity inside cells using pulses of light.
Karl Deisseroth subsequently adapted the discovery for neuroscience. He introduced the gene responsible for channelrhodopsin into rat nerve cells and demonstrated that blue light could trigger electrical signals in the neurons.
He later demonstrated that the same light-controlled mechanism could be used to manipulate nerve cells in the brains of living mice.
OPTOGENETICS TRANSFORMS BRAIN RESEARCH
The resulting technique, known as optogenetics, combines genetic methods with light-based control of neurons.
By targeting specific groups of nerve cells, researchers can activate or inhibit neural activity and observe the resulting changes in behaviour and brain function.
The technology has helped scientists investigate neural circuits associated with memory, emotions, movement and behaviour, as well as mechanisms involved in neurological and psychiatric disorders.
Researchers are also exploring possible medical applications. Among them are efforts to use optogenetic approaches to restore visual function in people with certain forms of vision loss.
THREE SCIENTISTS, ONE LANDMARK DISCOVERY
Karl Deisseroth is a professor of bioengineering, psychiatry and behavioural sciences at Stanford University in the United States.
Peter Hegemann is a German biophysicist whose research focused on light-sensitive proteins found in microorganisms. Georg Nagel, also from Germany, contributed to the study and characterisation of microbial opsins and demonstrated their ability to function as light-controlled ion channels.
Together, their discoveries established the scientific foundation for optogenetics and provided neuroscience with a powerful method for studying how specific groups of neurons control brain functions and behaviour.
The 2026 Nobel Medicine Prize recognises the progression from understanding how microorganisms detect light to developing a technology capable of precisely controlling neural activity in living organisms.