Here’s a look at the Nobel Prizes for science

It’s Nobels season — that time of the year when we find out which groundbreaking, paradigm-shifting, world-changing achievements beat out the rest to win what is arguably the most prestigious award on Earth. From a light switch for the brain to the discovery of an ultra-elusive subatomic particle hailing from beyond our solar system to a solution to one of the most enduring puzzles in all of organic chemistry, the researchers behind this year’s scientific prizes each revolutionized the ways that scientists understand the world around them. Take a look at the science behind each of this year’s awards.

A galaxy of nearly 90 billion neurons exists within a single human brain. But unlike stars in the void, neurons communicate with one another via some 100 trillion connections, allowing the human mind to learn, adapt and interact with its surroundings. For scientists to understand how individual actions arise from such complexity, they needed a tool to directly link neural circuits to specific behaviors, said Abdel El Manira, a neuroscientist at the Karolinska Institute in Stockholm.

Enter the bright idea that won. It’s a technology called optogenetics, which involves using light to precisely activate specific cells, like neurons, and watch how behavior changes. For their foundational contributions to optogenetics, biophysicists Peter Hegemann of Humboldt University in Berlin and Georg Nagel, of the Julius-Maximilians-Universität Würzburg in Germany, and neuroscientist Karl Deisseroth of Stanford University shared this year’s prize.

The prize winners’ story starts in an unlikely place: the eye spot of a single celled green alga called Chlamydomonas. In the early 2000s, Hegemann, then at the Max Planck Institute for Biochemistry in Martinsreid, Germany, and Nagel, at the Max Planck Institute for Biophysics in Frankfurt, discovered a unique protein in the alga’s eye spot. When illuminated, the protein generated an electrical impulse, enabling the organism to move.

Further research revealed that when the protein, called channelrhodopsin, was exposed to light, it opened like a pore, allowing positively charged ions to flow into a cell, generating the electrical impulse. Building on the Hegemann and Nagel’s work, Deisseroth began testing whether channelrhodopsin could be used to activate brain cells. He and his colleagues first inserted the gene for channelrhodopsin into cultures of rat nerve cells and found that the cells reacted to light instantaneously.

They then introduced the gene into nerve cells in the brains of living mice, along with optical fibers fed through the rodents’ skulls. By beaming blue light through the fibers, the researchers were able to control the movements of the rodents’ whiskers. This technology gave researchers the ability to test the links between certain brain circuits and behaviors.