Earlier this week, the Royal Swedish Academy of Sciences awarded the 2026 Nobel Prize in medicine to Peter Hegemann, Georg Nagel, and Karl Deisseroth for their discoveries leading to optogenetics, a technology that makes it possible to peer into the inner workings of the brain like never before.
After taking the call from Stockholm at 12:30 a.m. PT, Dr. Deisseroth, a neuroscientist and physician from Stanford University, spent the rest of the night fielding media calls, pausing to make school lunches before waking up his children to share the news.
“Dad, you’ve won all the prizes!” said his 10-year-old daughter Sophie, according to colleagues present for the big reveal.
Deisseroth was just heading to bed when he received the call from Stockholm that he had won the 2026 Nobel Prize in medicine. (AP Photo/Noah Berger)
“I woke up at 7 a.m. and saw a text from my mom that said, ‘We have news!!’” said Deisseroth’s 18-year-old son Alexander. “We all knew he deserved this, and he’s deserved it for a while. We’re insanely proud of him.”
Quirks & Quarks host Bob McDonald caught up with Deisseroth shortly after his win.
What was it like to get that call from Stockholm?
It was very unexpected… I’d just gone in to lie down and go to sleep and I was drifting off — not quite fully asleep — and at about 12:30 the call came.
My bedside phone was buzzing, but I didn’t react in time so it went to voicemail. And then they called my wife — they had her number somehow, I don’t know how — and she picked up and they said, ‘Can we speak to Karl?’
I’ve seen videos of you telling your kids the news. What was it like to share that moment with them?
It was very moving. They’re sweet kids, I love them. They know they always come first ahead of everything, but they also know and appreciate that their parents work hard and are curious about the natural world and biology and medicine, and so they have some appreciation for that. So I think they appreciated it also in that moment, and their excitement sort of comes through.
WATCH | Karl Deisseroth tells his family he won the Nobel Prize:
You share the prize with Peter Hegemann and Georg Nagel, how did you take their discovery and turn it into a tool to peer into the brain?
I’m interested in understanding how the brain works, and how it fails to work. It’s very hard to do precise interventions in the brain. You can observe things, you can record things, but it’s very hard to make a precise perturbation. But that’s really how you figure out how things actually work, right? You poke or wiggle the system somehow, the more specific the better.
And there wasn’t a good way of doing that.
So in 2004, I carried out a screen for genetic ways of targeting neurons so that we could affect their electrical activity. It was in a 24-well plate, so I could do many conditions at once. And, as is usual for me, I mixed high-risk and low-risk strategies together. It’s a nice way of hedging bets. So I tried some very low-risk, almost obvious, things. And then along with these I did the high-risk experiment, including this algal gene that Peter and Georg had described a couple years earlier.
Portraits of Deisseroth, Peter Hegemann and Georg Nagel are shown on a screen as they are awarded the 2026 Nobel Prize in Physiology or Medicine. (Pontus Lundahl/TT/TT News Agency)
I put that gene into neurons, and some of those wells in the plate I exposed to light and others I didn’t. And I looked for differences in the activation of the cell in terms of what we call depolarization of the membrane. And yeah, it was quite amazing that this high-risk strategy actually was the one that worked well.
How does it actually work then, in practice?
If you’re interested in testing what a cell type does in the brain, you build your DNA with the right targeting, and then you include this microbial light-gated channel as part of it. You wrap that up into what we call a vector, basically a modified virus that helps deliver the gene to cells. You concentrate that down, and then you inject a tiny bit of this very concentrated virus carrying your light-gated ion channel gene into your, let’s say it’s a mouse or a rat, and you put it into the right part of the brain that you’re interested in exploring. And then those cells become the only ones that are light sensitive in the brain.
Deisseroth celebrates with colleagues at Stanford University on Monday. (AP Photo/Noah Berger)
And then the final step is you bring in light. We have holographic displays that can deliver thousands of spots of light in three dimensions through the brain. And then you can see what happens.
Now that you have this tool, what can you do now that you weren’t able to before?
You can answer that very fundamental question: which cells actually matter for function? And now, there have been more than 10,000 papers published around the world — you know, which cells mediate survival drives like hunger and thirst, which cells mediate complex motivated behaviours, aggression and violence, or parenting and nurturing. There’s beautiful work done by Sheena Josselyn and Paul Frankland at [Toronto’s] Sick Kids Hospital on memory using optogenetics, which cells actually form memories.
And all these things you could never have done before because there would have been no way to just perturb one kind of cell or another. And that’s the power of the approach.
What’s next for you?
I feel as though the opportunities are still opening up. There’s so much more I want to do. I want to discover principles about brain function. I want to help people. I want to be able to tell my patients that we’re making progress on these very serious disorders. And I want to be able to do more outreach to the public.
Not only do people have the right to hear these stories and see what the science is telling us, but also they should know how science got here, and how it is that a gene from algae is helping us to understand ourselves. That’s not obvious, right? And it is important for people to understand how science can take a twist and a turn like that.
This interview was edited for length and clarity.
