The 2026 Nobel Prize in Physiology or Medicine Recognized a Sequence of Discoveries

The 2026 Nobel Prize in Physiology or Medicine recognizes not a single isolated discovery, but a sequence of research that began with the study of how algae respond to light and ultimately led to the creation of a tool for controlling neuronal activity. Optogenetics has given scientists a much more precise way to investigate how the brain works and has become one of the key methods in modern neuroscience, the BBC reports.

As a reminder, the 2026 Nobel Prize in Physiology or Medicine was awarded to American neuroscientist Karl Deisseroth and German scientists Peter Hegemann and Georg Nagel. The Nobel Committee recognized their discoveries concerning light-sensitive ion channels and optogenetics — a method that has enabled scientists to control the activity of individual nerve cells using light.

The development of optogenetics was an important milestone in brain research. The method makes it possible not simply to observe neurons at work, but to selectively activate or suppress their activity directly within a living nervous system. As a result, researchers gained a new tool for studying how memories, emotions, and behavior are formed, as well as which neural circuits may be involved in neurological and psychiatric disorders.

From Algae to Controlling Neurons

As early as the 20th century, scientists were trying to determine which areas of the brain were responsible for different bodily functions. However, the methods available at the time mainly allowed researchers to identify associations between activity in particular brain regions and behavior, but did not always enable them to establish a causal relationship.

The situation changed thanks to research into light-sensitive proteins found in single-celled organisms.

Peter Hegemann studied the single-celled green alga Chlamydomonas, which is capable of moving toward a source of light. The scientist was interested in how the organism detects light and converts that signal into movement.

In the early 2000s, Hegemann and Georg Nagel investigated a special protein known as channelrhodopsin. Located in the cell membrane, it functions as a light-sensitive ion channel.

When blue light strikes the protein, the channel opens, allowing charged particles — ions — to enter the cell. This changes the cell’s electrical state and enables it to transmit a signal.

The researchers discovered a crucial property of channelrhodopsin: if the corresponding gene is transferred into another cell, that cell also acquires the ability to respond to light. This opened up the possibility of using light-sensitive proteins not only to study algae, but also to control cells of other types.

How Light Learned to Switch Neurons On

The next decisive step was taken by Karl Deisseroth. His team introduced the channelrhodopsin gene into rat nerve cells.

In 2005, the scientists showed that exposing these neurons to blue light could trigger a neural signal. In other words, researchers gained the ability to control the electrical activity of nerve cells using light instead of conventional electrical or chemical stimulation.

In 2007, Deisseroth demonstrated that the approach could work directly in the brains of living mice.

This gave rise to optogenetics — a technology that combines genetic techniques with light stimulation to control the activity of specific cells.

The main advantage of the method is its high degree of precision. Researchers can target a specific population of neurons and observe, virtually in real time, how changes in their activity affect an animal’s behavior.

Why Optogenetics Changed Neuroscience

To understand how the brain works, it is not enough to know which neurons are active at a particular moment. Scientists also need to determine what role that activity actually plays.

Optogenetics has brought researchers closer to answering this question. Using the method, scientists have been able to investigate neural circuits involved in the formation of specific memories, emotional responses, and patterns of behavior.

The technique is also used to study the mechanisms underlying various neurological and psychiatric disorders. It helps researchers investigate processes associated, for example, with memory impairments, addiction, and changes in emotional behavior.

In essence, optogenetics transformed the brain from a system that scientists could primarily observe into one whose individual components could be selectively and controllably switched on and off.

Per Svenningsson, chair of the Nobel Committee for Physiology or Medicine, said that optogenetics has opened up possibilities for mapping the brain that researchers could previously only dream of. According to him, the technology has fundamentally changed scientists’ understanding of how the brain works.

From a Laboratory Tool to a Potential Treatment

Today, optogenetics remains primarily a research tool, but scientists are also investigating its potential medical applications.

One area of research is the restoration of vision in people with severe visual impairment. Researchers are attempting to use light-sensitive proteins to make certain retinal cells responsive to light and thereby partially restore the transmission of visual information.

At the same time, optogenetics has not yet become a universal treatment for disorders of the nervous system. Before it can be used clinically, a number of technical and biological challenges must be addressed, including the safe delivery of genes, precise targeting of the necessary cells, and controlled stimulation.

Nevertheless, the principle itself has already transformed experimental neuroscience. Scientists have gained the ability to test causal relationships directly in the functioning brain: rather than simply recording that a particular group of neurons is active during a certain behavior, they can temporarily switch those cells on or off and observe how the outcome changes.

Who Received the Nobel Prize

Karl Deisseroth was born in Boston in 1971. He received his PhD in 1998 and his medical degree in 2000 from Stanford University. He is a professor of bioengineering, psychiatry, and behavioral sciences at Stanford and an investigator at the Howard Hughes Medical Institute.

Peter Hegemann was born in Münster in 1954. In 1984, he completed his doctoral dissertation at the Max Planck Institute of Biochemistry in Martinsried. He is currently a senior professor of neuroscience at Humboldt University of Berlin.

Georg Nagel was born in Weingarten in 1953. He received his doctoral degree from the University of Frankfurt in 1988. Nagel is a professor of molecular plant physiology and biophysics at the University of Würzburg.

Their research related to the discoveries recognized by the Nobel Prize was conducted at the Max Planck Institute of Biochemistry in Martinsried.

Follow NEWS.am Medicine on Facebook and Twitter