The 2026 Nobel Prize in Physiology or Medicine was jointly awarded on Monday to Karl Deisseroth, Peter Hegemann and Georg Nagel for their work in optogenetics, a field of neuroscience that looks at the activity of individual neurons to link them to specific behaviors.
Here & Now host Robin Young spoke with Deisseroth, one of the three Nobel winners and professor of bioengineering and psychiatry and behavioral sciences at Stanford University, shortly after he learned he had won the prestigious prize.
“It was very disorienting, unexpected,” Deisseroth, a Boston native, told Young. “I had I’m a bit of a night owl, but I was working late, and I had just gone to bed and was at the interface between sleep and wake. And then the call came, and so I was not sure if it was a dream or not. I’ll tell you that.”
4 questions with Karl Deisseroth
What is optogenetics?
“What we figured out was how to use light to control cells in the brain.
“And so, this is different from how you normally think about light as an imaging tool to look at things. In this case, it’s totally different. We’re using light to make things happen, to turn cells on or off, but deep within a brain that’s functioning in an animal or even a person that’s moving and behaving and living.
“And this is so powerful because what we can do, the way this works is we make cells sensitive to light by introducing a gene from algae. From single-celled algae that gives rise to a light responsive ion current, a flow of charged particles, which is electricity. So basically, long story short, we can use light to create electricity in exactly the cells we give the gene to.”
And maybe change the way the brain is reacting to something?
“Yes, for example. So normally, we take for granted the choices we make and the priorities we think. Of course, survival-drives like hunger and thirst will do what it takes to make them happen. If we need to nurture our young or if we need to be aggressive or defensive, we’ll do the right thing.
“In reality, all these actions and priorities are set by cells, and the cells are competing with each other and deciding what to do based on the connectivity of the neural circuits. And what optogenetics has let us do is to tease that apart and say, ‘OK, here’s why this action is taken, here’s why this priority is rising to the top, and here’s how to change it.’
“So, it’s interesting to get to that level of understanding of why we do what we do.”
You’re also a psychiatrist, and we’re reading that your work made you very frustrated because you couldn’t explain to patients why they were having their suffering. Is that part of this?
“Yes, it is very much so. So, psychiatry is probably the field of medicine that is most in need of explanatory power like that. Why is something happening? What is the biological basis for it? And this is in part not through any lack of effort or trying, but because the brain is very complicated. It’s very hard to study, very fragile and intricate.
“And what optogenetics does is it gives us the tools to pierce through that intricacy. Optogenetics is fast. Optogenetics is precise, just like the brain. So, we can keep up with the brain and make things happen.
“As a psychiatrist, it’s so exciting to look at this and think, ‘Oh, this is a way we can come to a deeper understanding of ourselves.”
How can the discovery be used to treat people?
“It’s already been tested in human beings who are blind, and this is a disease called retinitis pigmentosa where there’s loss of cells that’s due to neurodegeneration.
“And optogenetics has been used to confer light sensitivity back on these people and let them see things that they couldn’t see before. And that’s just one of many examples.
“But once you understand the cells that matter, which is something we’ve lacked for so long in psychiatry. Once you understand the cells that matter, you can design any kind of treatment. You could design a medication that targets those cells grounded for the first time and knowing what matters. And that’s the real power of optogenetics as it tells you what matters.”
This was edited for clarity.
Hafsa Quraishi produced and edited this interview for broadcast with Michael Scotto. Scotto adapted it for the web.
This article was originally published on WBUR.org.
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