Nobel Prize in Physiology or Medicine "Optogenetics": Precisely controlling brain nerves and thinking with a beam of light

An official illustration from the Nobel committee depicts a woman playing chess, her brain neurons being precisely illuminated by the beam of a light switch. This picture vividly symbolizes the revolutionary breakthrough of scientists using the photosensitive properties of green algae to install switches on brain cells, achieving precise control of thinking and behavior with a beam of light. (Extracted from Nobel official website)

The human brain has tens of billions of intertwined nerve cells. In the past, it was almost impossible to control a few of these cells independently without affecting their neighbors. Optogenetics, which won the Nobel Prize in Physiology or Medicine this year, is a revolutionary technology that installs "exclusive light-sensitive switches" on specific brain cells.

Popular science information from the Nobel Committee points out that traditional research on the brain mainly relies on electrode stimulation or drugs. However, currents will rush along the brain tissue, and drugs will spread throughout the body and act slowly. It is always difficult for scientists to accurately determine "which cells are responsible for which emotions or actions." The break in this impasse that has plagued the academic community for decades actually comes from single-celled green algae in ponds.

German scholars Peter Hegemann and Georg Nagel discovered that although green algae have no eyes, they can swim towards the sun accurately. The key lies in the fact that there is a special "photosensitive protein" on the surface of green algae. As long as specific light is illuminated, it will open a channel to allow electric current to pass through. American scholar Karl Deisseroth then suddenly had the idea to use genetic engineering to put this "green algae photosensitive gene" into specific brain nerve cells of animals.

Instant switch on and off when illuminated, blind patients clinically regain their sense of light

In this way, only the target nerve cells equipped with the green algae switch will respond to the light, while the millions of surrounding cells without the switch will not be affected at all. Scientists can "turn on" or "turn off" target cells at any time within a thousandth of a second by shining light through optical fibers thinner than a hair. In animal experiments, researchers can make already-fed mice instantly start eating or directly switch specific fear and memory responses by simply turning on the light source.

The technology has become a standard tool in labs around the world to unravel brain circuits for memory, sleep, depression and Parkinson's disease. Due to the need to implant genes and optical fibers, direct manipulation of the brain at this stage is still focused on animal experiments; however, the medical community has advanced it to human ophthalmic clinical trials. By injecting photosensitive proteins into the retina, patients who are blind due to genetic eye diseases can successfully see the outline of objects again.