2026 Nobel Prize in physiology or medicine honored Karl Deisseroth, Peter Hegemann and Georg Nagel for their work developing optogenetics – a technique that allows researchers to control the activity of neurons with light.

The Conversation Weekly podcast talked to Karl Deisseroth, a neuroscientist at Stanford University, about his journey developing optogenetics and its potential to treat a wide range of neuropsychiatric conditions. What follows is an edited transcript of the podcast.

Take us back to the early 1990s. You’re training to be a doctor and you start a rotation working with psychiatric patients. What questions about the brain did that raise for you?