The Nobel Prize in Physiology or Medicine has been jointly awarded to Karl Deisseroth, Peter Hegemann and Georg Nagel for their research on light-gated ion channels and optogenetics.

The prize is worth 12 million Swedish kronor, equivalent to about $1.2 million, according to France 24.

Deisseroth, 54, Hegemann, 71, and Nagel, 73, were recognised for research that led to the development of optogenetics, a method that uses light to control cells and has become an important tool for studying the brain.

The Nobel Committee said the method “is now being used in laboratories around the world to reveal the brain’s mysteries.”

Deisseroth is based at Stanford University in California, while Hegemann is affiliated with Humboldt University in Berlin and Nagel with the University of Wurzburg in Germany.

The prize was announced at the Karolinska Institute in Stockholm, marking the start of this year’s Nobel week.

Last year, the Nobel Prize in Physiology or Medicine was awarded to three scientists for their discoveries concerning the immune system.

The medicine prize will be followed by the physics prize on Tuesday, chemistry on Wednesday and literature on Thursday. The Nobel Peace Prize will be announced on Friday, while the Nobel Memorial Prize in Economic Sciences will be announced on October 12.