Light switches neurons: Stanford video explains the Nobel-winning method optogenetics

Stanford Medicine has published an explainer video on optogenetics on its official YouTube channel – the method for which Stanford researcher Karl Deisseroth shares the 2026 Nobel Prize in Physiology or Medicine with Peter Hegemann (Humboldt University of Berlin) and Georg Nagel (University of Würzburg). The Nobel committee honoured discoveries that make it possible to switch the activity of individual nerve cells in a living brain on or off.

The principle, according to Stanford: light-sensitive proteins from microorganisms, called opsins, are genetically introduced into specific nerve cells. Ultrathin, flexible optical fibres deliver light into the brain; an opsin that responds to blue light makes the cells fire, while one for yellow light inhibits them. The original protein, channelrhodopsin, was discovered in algae by Hegemann and Nagel. Deisseroth's team found that mammalian brains already contain a natural cofactor it needs.

In experiments on mice, Deisseroth used the method to identify circuits involved in Parkinson's disease and reverse symptoms, and to induce and relieve depression-like symptoms. According to Stanford, the technique can also be adapted to cells such as those in the heart or pancreas and might one day be used in humans with the help of gene therapy.