Scientists just hacked the brain using lasers. Now they can turn off parts of it

For centuries, the human brain has been the greatest mystery and a dream for scientists to decode. Scientists have tried to debunk how it forms memories, generates thoughts, feelings, and emotions, and makes a person act in a certain way. Recently, three scientists, including neuroscientist Karl Deisseroth of Stanford University, biophysicist Peter Hegemann of the Humboldt University of Berlin, and biophysicist Georg Nagel of the University of Würzburg, have been awarded the Nobel Prize for discovering the field of optogenetics, a revolutionary study about the human brain and a foundation for the new era of neuroscience. The announcement was made on October 5, 2026, and the video has received 171,000 views since.

A breakthrough in neuroscience

Two of the laureates shared their delight with CNN at winning this year’s prize. Deisseroth was at his bedside when he received a phone call. A clip shows him revealing the news to his family members who were jumping with excitement. Nagel, meanwhile, learned that he won the prize while on a terrace in the sun in Italy.

“How does an organ composed of nearly 90 billion remarkably diverse neurons, connected through vast circuits, transform this complex interplay of perception, memory, prediction, and decision-making into a single, purposeful behavior?” asked Abdel El Manira, a member of the Nobel Prize committee and a neuroscientist at the Karolinska Institute in Sweden, during the award announcement. “Answering this question…requires establishing cause and effect.” Deisseroth, Hegemann, and Nagel created a tool to do just that.

Most fascinating biological mystery

Optogenetics works by genetically modifying an animal’s targeted neurons to have special light-sensitive proteins. Shining light on these cells triggers them, allowing researchers to investigate what specific cells do in the brains of live animals. Dr. Joe took the example of firefighters and fire. Where there is fire, there are firefighters, but it doesn’t imply that firefighters caused the fire. Similarly, whenever a person displays a certain behavior, the corresponding brain cells activate, but no one knows whether they caused the behavior or were simply responding to it. The three laureates have created a sort of neuronal switch that can turn nerve cells on and off. Originally, the answer came from blue-green algae.

Algae held the secret

The story began in the early 2000s when Hegemann and Nagel stumbled upon a protein called “channelrhodopsin” in a type of green algae named “Chlamydomonas reinhardtii.” The algae is famous for its ability to swim towards light. Investigation revealed that it senses the light with an eyespot, a tiny orange dot on the surface that contains a light-capturing molecule, retinal. Only half a millisecond after the light reached the eyespot, an electrical impulse was triggered. The protein held the key to this light sensitivity. When opened, the protein allowed charged ions to rush into the cell, triggering an electrical impulse.

Sparks of light

There are approximately 86 billion neurons in the human brain, per a study published in BRAIN. But the entire process worked about 20 times faster than that of a human eye when light reaches it. Adding the protein to other organisms could make them light-sensitive too. Hegemann and Nagel then inserted the protein into an embryonic human kidney to copy the unique property.

Around the same time, Deisseroth was starting his own laboratory at Stanford to study how electrical impulses could be fired by specific neurons. He was struck by his patients’ suffering and their need for help. He often wondered how the brain can work so differently in different people. Why it caused depression in some people, while others felt excited.

DNA debunked the mystery

Deisseroth asked the other two scientists to access the DNA that encoded the protein “channelrhodopsin.” After copying the two genes from the DNA, he put it into rat neurons and made them react to blue laser light, even controlling the movements of mouse whiskers. “It was the approach with the highest risk, but it turned out to be the one that worked best, and that was a valuable lesson,” Deisseroth explained in a statement. “The ability to activate or silence neurons in the brain using laser light has opened the door to unprecedented precision,” Andrea Benucci, a neuroscientist at Queen Mary University of London, tells CNN.

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