Neuroscientist Karl Deisseroth, alongside German scientists Peter Hegemann and Georg Nagel, won the 2026 Nobel Prize in Physiology or Medicine for pioneering a new technique in the field.
The award-winning trio banded together and used each other’s research to create optogenetics. The new technique uses light to control the activity of individual nerve cells in living brains. The new technique has revolutionized the field, advancing the study in ways yet to be imagined.
Before The Nobel Prize
Back in 2004, Deisseroth, who’s a Stanford University professor, launched his lab where he focused on advancing optogenetics research. While Deisseroth was busy perfecting his technique, Hegemann and Nagel were busy discovering channelrhodopsin, a light-sensitive protein in single-celled algae.
When Deisseroth later adapted the protein into a light-controlled switch for neurons in mammalian brains, it allowed researchers to study how specific neural circuits function. The Nobel Assembly at Karolinska Institute commended their work, stating it ‘laid the foundation of a new era in neuroscience.”
According to the institute, the technique has made it possible to directly see how nerve cells shape memories, feelings and behaviors within a living brain.
“Optogenetics provides opportunities for mapping the brain in a way that we could once only dream of,” Per Svenningsson, chair of the Nobel Committee for Physiology or Medicine, said in a statement.
How Light Transformed Brain Science
Optogenetics can show how circuits influence movement, memory, emotions and behavior in the brain. Deisseroth simply described his work as using “light to turn on or off cells in the brain.”
“We can take a molecule from algae and it lets me turn cells on or off, to stimulate them, or to turn them on or off with the flip of a switch — a laser,” he said. “That’s how any 10-year-old would understand a system: by poking it. That’s what we’re doing with optogenetics. We’re poking the brain.”
By activating or blocking neurons with light, researchers can investigate cause-and-effect relationships that are difficult to establish through brain imaging alone. Before the advent of optogenetics, researchers used functional MRI, electrical stimulation and drugs to study brain activity. While these methods could reveal brain activity patterns, they could not show direct cause and effect. Optogenetics, by contrast, allows researchers to investigate how direct activity using light influences neural circuits and behavior.
How Optogenetics Is Changing Clinical Practice
Optogenetics is not yet used in routine clinical practice, but it has given researchers a way to test how specific neural circuits contribute to brain disorders. These findings have helped increase understanding of several conditions, including Parkinson’s disease, depression and anxiety. .
Parkinson’s Disease
Deisseroth and neuroscientist Anatol Kreitzer used the award-winning technique to investigate how different groups of nerve cells in the brain influence movement. The findings helped to explain the underlying mechanism behind Parkinson’s Disease and how changes in the brain signaling contribute to it.
His work also showed that targeting specific nerve cells could reverse Parkinson’s Disease symptoms in mice. The research approach is not yet approved to treat patients.
Vision Loss
The most advanced clinical work on optogenetics is aimed at restoring vision in people with retinal disease. Researchers at GenSight Biologics are currently testing whether the technique can restore vision in people with advanced retinitis pigmentosa, an inherited disease that damages the retina and can lead to blindness.
An experimental treatment currently in Phase 1/2a clinical trial uses gene therapy to make surviving retinal cells sensitive to light. Patients then wear specialized goggles that convert images into light patterns, stimulating those cells to send visual information to the brain.
The company behind the study released the results, calling the potential therapeutic effect encouraging.
Anxiety
Researchers have also used optogenetics to investigate how specific connections in the amygdala, a brain region involved in processing emotion, influence anxiety-related behavior.
In a study published in Nature, scientists manipulated connections between different parts of the amygdala in mice. Activating one pathway reduced anxiety-related behavior, while inhibiting it increased such behavior.
The findings reveal that the effects of neural activity depend on the specific circuit involved, providing a more detailed picture of the brain mechanisms behind anxiety.
Depression
Deisseroth and his colleagues used optogenetics to investigate how dopamine neurons contribute to depression-related symptoms.
In research published in Nature, the team manipulated dopamine-producing neurons in the ventral tegmental area, a region involved in motivation and reward. Stimulating these neurons in mice exposed to chronic stress, improved behaviors associated with motivation and the ability to experience pleasure. Inhibiting the same neurons produced the opposite effects.
The findings helped establish a causal link between specific neural activity and multiple depression-related behaviors.
Autism And Social Behavior
Researchers have used optogenetics to better understand autism and social behavior conditions.
In a study published in Science Translational Medicine, Deisseroth studied mice lacking CNTNAP2gene, a gene associated with autism. The researchers used light to alter the balance between excitatory and inhibitory activity in the prefrontal cortex.
The findings showed that adjusting brain activity reduced hyperactivity and improved social interaction in mice. The research also suggests that these behaviors may be influenced by an imbalance in brain signaling.
Addiction
In a study published in Addiction Biology, Deisseroth used optogenetics to inhibit specific brain regions in rats trained to seek cocaine. The researchers found that suppressing activity in these regions reduced cocaine-seeking behavior when the animals were exposed to cues or conditions associated with the drug. The findings also identified brain pathways that contribute to relapse and potential targets for future addiction research.
Schizophrenia
Optogenetics has allowed researchers to investigate neural circuit dysfunction associated with schizophrenia.
Using the technique to trigger and reverse social-behavior deficits in mice, the researchers found that manipulating specific brain cells produced changes in social interaction. They also discovered it created abnormal brain-wave patterns previously associated with schizophrenia and autism in humans.
The findings provided experimental evidence linking changes in brain activity to social difficulties, helping researchers investigate how similar mechanisms may contribute to psychiatric disorders.
What’s Next for Optogenetics?
There are several ways researchers are trying to develop optogenetics and expand it beyond its current capabilities.
One way is improving how light reaches neurons deep inside the brain. Blue light is widely used in optogenetics. However, this type of light has limits in how far it can reach because it is absorbed as it travels through tissue. To combat that problem, optogenetics researchers are developing red- and far-red-light-sensitive proteins that can respond to longer wavelengths.
Researchers are also aiming to identify targets for treatments that do not require light-sensitive proteins. In a 2025 roadmap published in Nature Neuroscience, Deisseroth and his co-authors describe how discoveries about the brain’s neural circuits could guide the development of medicines and refine approaches such as deep-brain stimulation.
For example, researchers could use optogenetics to identify which circuits contribute to Parkinson’s symptoms, then investigate whether existing or experimental treatments can influence those same pathways. This indirect approach could extend the technique’s impact beyond conditions that can be treated with light.
