Per Svenningsson, chair of the Nobel Committee for Physiology or Medicine, explained: “Optogenetics provides opportunities for mapping the brain in a way that we could once only dream of.”

Before, the inner workings behind feelings, behaviours and bodily functions were more of a mystery to scientists.

Optogentics is a way to illuminate brain pathways, using a special protein borrowed from algae that scientists use to control cell electrical activity using light.

In the early 2000s, Hegemann and Nagel discovered channelrhodopsin, the algal protein with unique properties.

Researchers have since been able to study nerve cells and pathways in animals to see and discover more about what they do.

The Nobel Committee said: “Using light, researchers are now able to switch individual neural circuits on or off in the brain. They can bring memories to life, create feelings, drive behaviours and study the types of neurons that are involved in various psychiatric and neurological disorders.”

That is providing important insights into how the nervous system interacts with various cells in other areas of the body, such as in the heart and gut, the committee added.