Kateriya, now a professor at Jawaharlal Nehru University in New Delhi, worked in Hegemann's lab in Germany between 2000 and 2004. During that period he identified two DNA sequences in the single-celled green alga Chlamydomonas that encode channelrhodopsins, light-sensitive proteins that let cells generate electrical signals when exposed to light. He published those findings in 2002 and 2003, with his name listed as a co-author on both studies.

That biological mechanism gave Deisseroth and others the tool they needed to build optogenetics, a technique that uses light to control nerve cells with precise timing. Researchers have since used it to study memory, behavior, and other brain functions with a level of temporal precision not available through earlier methods.

Kateriya has continued collaborating with Hegemann, co-authoring more than 25 papers with him since their work together began. "I am really content and satisfied," Kateriya said of the prize.

The Physiology or Medicine announcement opened this year's Nobel announcements. The Physics prize went to Francis Halzen for his contributions to the IceCube neutrino observatory at the South Pole, which detects high-energy neutrinos from space using a cubic kilometer of ice as its detector. The Chemistry prize was awarded to Henri B. Kagan and Kenso Soai for discovering non-linear effects and autocatalysis in asymmetric organic synthesis, work that addresses why life favors a single molecular orientation, known as homochirality.

Anne Carson won the Nobel Prize in Literature; the committee described her work as "bold and inventive," saying she creates new forms for contemporary literature through dialogue with classical tradition. The Peace Prize went to Navi Pillay, a South African jurist recognized for her efforts fighting apartheid and building international justice, including work tied to Rwanda and the United Nations.

The Nobel Prize in Economic Sciences, added in 1968, is expected to be announced on Monday.