Controlling nerve cells in the brain with light, recalling lost memories, or enabling a person who has lost his sight to perceive the objects around him again... Some of these ideas, which once reminded us of science fiction movies, have turned into real applications that scientists are working on in laboratories today.
Discoveries in the field of optogenetics, which combines genetic engineering and light, earned the 2026 Nobel Prize in Physiology or Medicine to Karl Deisseroth, Peter Hegemann and Georg Nagel. The developed method enabled scientists to control the activities of nerve cells with the help of light, with the idea coming from microalgae, and paved the way for new research in different areas, from vision loss to Alzheimer's, from addiction to other neurological diseases.
One of the most remarkable developments in the use of optogenetics in humans occurred in 2021. A patient who had vision loss for nearly 40 years began to partially perceive objects in front of him with the help of special glasses, following experimental treatment. The research, which revealed that the patient was able to regain some visual functions, was considered an important development showing the clinical potential of the method.
Head of the Department of Ophthalmology at the University of Pittsburgh School of Medicine and Director of the UPMC Vision Institute, one of the pioneers of the research that enabled a visually impaired patient to regain some of his visual function with the optogenetic method in 2021. José-Alain Sahel explained this promising method, which we became acquainted with thanks to the Nobel Prize.
Stating that five years later, they conducted a larger study on optogenetic treatment on October 7 and received positive results in 7 out of 10 patients, Sahel said, "Five years ago, we showed for the first time that the optogenetic method could help restore some aspects of visual functions in a visually impaired patient. In our new study, we achieved promising results in a larger group of patients. These findings provide additional evidence that optogenetic treatment can significantly restore visual function in advanced stage retinitis pigmentosa patients." he said.
Sahel explained that they are working on new technologies that will enable visual information to be transmitted to the retina more precisely, and expressed his expectations for the future with the following words: "Although more research and clinical tests are needed, the progress made in the last few years is extremely promising. We are optimistic that continuous improvements in the developed technologies can further increase the visual functions that patients can regain."
The optogenetics method is not limited to studies on vision loss. Scientists also use this technology to understand how memory is affected in Alzheimer's disease and which nerve cells in the brain manage addiction-related behaviors. Some findings from animal experiments show that activating certain nerve cells with light can help recall forgotten memories and change addiction-related behaviors.
Biotechnology expert Dr. Semih Tareen evaluated the potential of optogenetics in Alzheimer's and dementia research. "The field of optogenetics can actually be a positive treatment for diseases such as Alzheimer's disease, which causes dementia, memory loss and so on. We know this from mouse experiments," Tareen said.
Explaining that researchers were able to reactivate certain nerve cells in mice with Alzheimer's-like memory loss with the help of light, Tareen explained how this method works as follows:
"They give this receptor called channelrhodopsin to the brains of mice, and in this way, ion exchange is enabled and this is triggered by light. In other words, two signals are needed to the mouse's brain. First, this channel needs to be inserted. They do this with genetic engineering."
The channelrhodopsin that Tareen mentioned is a light-sensitive protein found naturally in some microalgae. Through genetic engineering, certain nerve cells are made to produce this protein. Then, light can be given to these cells and their activities can be controlled. Thus, scientists can examine the effect of activating specific memory-related neurons on behavior.
Explaining the second stage of the method used in the experiments, Tareen said, "Secondly, they activate it with an optical light using optical fiber, and thanks to that activation, ion exchange is provided to these cells. In this way, these nerve cells are activated, they come to life, and in this way, they enable mice with memory loss to regain this memory, and in these experiments, there are experiments of scaring the mice I mentioned and freezing them in the face of that frightening signal. They can remind a mouse that has forgotten to do this there again."
This is not being specifically studied in human experiments at the moment, but this may happen one day, and even a scientist named Karl Deisseroth, one of the Nobel Prize winners, has a company called MapLight Therapeutics, and this company wants to focus on such studies.
Tareen stated that remarkable results were also obtained in animal experiments regarding addiction. Explaining the experiments carried out with rats showing 'drug'-seeking behavior, Tareen said, "When the relevant nerve cells are activated with light, this 'drug'-seeking behavior, that is, reward-seeking behavior, disappears."
Similar experiments are being conducted on the use of optogenetics in addiction. There are experimental models for 'drug' addiction, especially in rats. For example, a rat learns that it will be given a 'drug' when it presses a button, and develops addictive behavior by pressing this button repeatedly.
Two steps are required to use optogenetics in these rats. The first is the insertion of light-sensitive ion channels into certain nerve cells in the brains of rats through genetic engineering. The second is to give light through a fiber optic cable to activate these nerve cells.
They observe that when these nerve cells are activated by light, the rats' drug-seeking behavior, that is, reward-seeking behavior, disappears.
