Nobel Prize in Physiology or Medicine 2026

Optogenetics: Using Light to Study the Brain

Laureates: Karl Deisseroth, Peter Hegemann and Georg Nagel

The brain contains billions of nerve cells that communicate through electrical and chemical signals. Understanding how these cells work together is a central question in neuroscience. The development of optogenetics has provided researchers with a way to control the activity of selected nerve cells using light.

The 2026 Nobel Prize in Physiology or Medicine was awarded jointly to Karl Deisseroth, Peter Hegemann and Georg Nagel for their discoveries concerning light-gated ion channels and optogenetics. Their work enabled researchers to use light to switch the activity of selected nerve cells on or off, creating a powerful experimental approach to understanding how the brain functions.

The Nobel winning research brought together discoveries from different areas of biology and medicine, connecting the study of microorganisms with the investigation of the mammalian brain.

Karl Deisseroth, a professor of bioengineering and of psychiatry and behavioural sciences at Stanford University in the United States, and an investigator at the Howard Hughes Medical Institute, helped establish optogenetics as a practical tool for neuroscience. His research demonstrated how light-sensitive proteins could be introduced into neurons and used to control their electrical activity.

Peter Hegemann, Hertie Senior Professor of Neuroscience at Humboldt University of Berlin, Germany, made fundamental contributions to understanding how microorganisms detect and respond to light. His research helped uncover the properties of proteins that would later become central to optogenetics.

Georg Nagel, a professor associated with research in molecular plant physiology at the University of Würzburg, Germany, collaborated in the discovery and characterisation of these proteins. His work helped establish that channelrhodopsin functions as a light-gated ion channel, capable of converting a light stimulus into an electrical response.

Hegemann and Nagel's investigations into light-sensitive proteins in algae laid the foundation for Deisseroth and other researchers to adapt these proteins for controlling neurons. Together, their contributions established a new way to investigate the relationship between neural activity and behaviour.

The research began with the study of light-sensitive proteins in microorganisms. These proteins respond to light by regulating the movement of ions across cell membranes. Hegemann and Nagel contributed to the discovery and characterisation of channelrhodopsins, while Deisseroth helped establish their use as tools for controlling neuronal activity.

In optogenetics, researchers introduce genes encoding light-sensitive proteins into selected cells. Light can then be used to influence the electrical activity of those cells. This allows scientists to investigate how particular neurons contribute to the functioning of neural circuits.

The method has become a research tool for studying brain activity and behaviour. By controlling selected groups of neurons and observing the resulting responses, scientists can investigate the relationships between neural activity and specific functions. It provides a way to test experimental questions that cannot be answered through observation alone.

Optogenetics is a research technique, not in itself an established treatment for neurological disorders. Its contribution lies in enabling more precise investigations of the brain and improving scientific understanding of how neural circuits function.

The 2026 Nobel Prize recognises the discoveries that made this approach possible and its development into a tool for neuroscience.