Karl Deisseroth, a Stanford University professor of bioengineering, psychiatry, and behavioral sciences, will receive the 2018 Kyoto Prize for advanced technology. Deisseroth, who is also a Howard Hughes Medical Institute investigator, will be honored for pioneering optogenetics and the optogenetics-enabled development of causal systems neuroscience — the science of establishing causal relationships between nerve-circuit activity and behavior, rather than merely observing correlations between them. Optogenetics allows scientists to manipulate the activity of nerve cells in an animal's brain. Genes encoding light-sensitive proteins, called opsins, are inserted into specific nerve cells. Then a pulse of laser light, delivered through a hair-thin optical fiber implanted in the brain, can turn these cells' signaling activity on or off. By observing how the animal behaves when the signaling is either active or inactive, scientists can deduce the cells' function. The tool has enabled researchers to better understand brain disorders such as schizophrenia, depression, and Parkinson's disease. "A brilliant and innovative investigator, Karl has created a revolutionary technology that has broadened our understanding of brain disorders and may one day yield treatments to the millions with these disorders," said Lloyd Minor, dean of the Stanford School of Medicine. "His receipt of the Kyoto Prize is inordinately well-deserved and the product of his unmatched scientific vision." The Kyoto Prize has been awarded annually since 1985 by the Inamori Foundation, a Japanese charitable organization, in three separate categories: advanced technology, basic sciences, and arts and philosophy. The prizes, which consist of a diploma, a 20-karat-gold medal and a gift of 100 million yen ($913,000), will be awarded at a ceremony in Kyoto, Japan, in November. A delegation from the foundation visited Deisseroth at Stanford to inform him that he would be receiving the award. "I can tell you I didn't do much math or engage in abstract thought for the rest of that day," Deisseroth said. Deisseroth is the youngest recipient of the prize ever. "This technology has been a long time in the making and has undergone a lot of development and improvement from the outstanding students, postdoctoral fellows, and staff members in the lab,” Deisseroth said. “Meanwhile, we and others around the world are continuing to achieve new discoveries and insights with optogenetics." Deisseroth's lab developed the basic components of optogenetics between 2004 and 2009. Between 2008 and 2018, his lab elucidated the inner workings of opsins, allowing them to develop variations of these molecules and enabling more richly detailed, precise, and versatile exploration of neural circuits. Today, thousands of laboratories around the world routinely employ Deisseroth's methodology and opsins to identify the brain circuitry responsible for specific behaviors, both healthy and maladaptive. Their findings have given rise to thousands of publications in peer-reviewed journals.