Nobel Prize in medicine honors pioneers of light-controlled brain research

On Oct. 5, the Nobel Assembly at the Karolinska Institute in Stockholm awarded the 2026 Nobel Prize in Physiology or Medicine jointly to Karl Deisseroth, Peter Hegemann and Georg Nagel for their contributions to understanding how the brain works and developing optogenetics.

Optogenetics is a technique that uses light-sensitive proteins to control nerve cell activity, allowing researchers to study how neural circuits shape memories, feelings and behavior in the living brain.

According to the press release, in the early 2000s Hegemann and Nagel discovered the light-sensitive protein channelrhodopsin in the single-celled alga Chlamydomonas, driven by Hegemann’s interest in how it could swim toward a source of light. They found that the protein opened a channel when exposed to blue light, allowing charged ions to flow into the cell and creating an electrical impulse. They also found that cells became light-sensitive when the protein was introduced into them.

Deisseroth introduced the gene for channelrhodopsin into rat nerve cells. By illuminating the cells with blue light, he triggered a nerve signal. In 2005, Deisseroth published the results. Two years later, he used this light-controlled switch to control nerve cells in the brains of living mice.

Optogenetics lets researchers study neural circuits more precisely and is being explored for clinical use, including attempts to restore sight in people with visual impairment.

The prize money of 12 million Swedish kronor (about $1.2 million) will be divided equally among the three researchers.