Over decades, scientists have pieced together what different neurons in the brain and spinal cord do by studying genes active in specific cell populations and by deleting those cells to observe the effects. But those methods have limits: brains can adapt to the loss of neurons, and early developmental losses can alter how remaining circuits form. A far more powerful approach would be to turn neurons on and off in an otherwise intact brain.
That capability is now a reality thanks to optogenetics. The Nobel Committee announced today that Karl Deisseroth, Peter Hegemann and Georg Nagel share this year's prize for developing the technique. Starting from studies of single-celled algae that swim toward light, the three researchers and many collaborators built a method that lets scientists mark neurons carrying specific genes and alter their activity with beams of light.
Optogenetics has become a cornerstone of modern neuroscience, enabling experiments that were previously impossible. Researchers can now activate or inhibit selected neurons in real time to probe their roles in behaviour, memory, disease and more. The Nobel citation highlighted how the work has opened new avenues for understanding the brain and for potential future therapies.