Skip to main content

Scientists manipulated mice to make them lose track of time

Scientists manipulated mice to make them lose track of time


Dopamine makes the time fly

Share this story

SV Darmstadt 98 v FC Ingolstadt 04 - Bundesliga
Photo by Simon Hofmann/Bongarts/Getty Images

The mystery of why “time flies when we’re having fun” is a little closer to being solved thanks to scientists who manipulated mice brains using light.

In a study published today in the journal Science, researchers at Portugal’s Champalimaud Centre for the Unknown stimulated certain brain cells (or neurons) in mice to make them produce more of a much-hyped chemical called dopamine. Dopamine can play a role in everything from attention to reward, and previous work suggests that it influences time perception, too, according to study co-author Bassam Atallah. When the scientists made mice produce more dopamine, the creatures underestimated time — meaning that it probably felt like time was going more quickly than it objectively was. Blocking the neurons from producing dopamine made them overestimate the amount of time that passed.  

Though the study isn’t in humans, we do have very similar brain structures, says Atallah. The results tell us more about the biology behind measuring time and suggest that one day we could understand exactly what’s going on when it seems like the day is dragging or flying by.

Producing more dopamine can slow down the internal clock

Before they could control mice brains, researchers had to spend months teaching the animals how to estimate time. It worked like this: There was a contraption with three holes. The mouse stuck its nose in the hole in the middle, and a tone played. Some time would pass, and then another tone would play. If time that passed between the two tones was longer than 1.5 seconds, the mouse would get a reward only if it put its nose in the hole on the left. If the tone was shorter than 1.5 seconds, the mouse would get a reward only for putting its nose in the hole on the right.

By observing whether the mice knew which hole to go to, the researchers could figure out whether the animals could tell if more or less than 1.5 seconds had gone by. “The mice take two to three months to get very good, but the best ones are arguably as good as humans are,” says Atallah. “Though some mice are brighter than others.”

The next step was figuring out what’s happening in the brain as the mice make their decisions. To do this, the scientists inserted special proteins into the brains to make the dopamine-producing neurons light up whenever they’re active. This way, by measuring how much light gets released when the mice were being tested, they could see how much dopamine was involved in the process. The amount of dopamine increased when they heard both the tones.

This isn’t just correlation

But that could be a coincidence. It doesn’t necessarily prove that dopamine actually causes mice to figure out how much time passed. To do this, the researchers manipulated the neurons using a very precise technique called optogenetics. In optogenetics, you use light to turn on or turn off certain neurons. The researchers stimulated the neurons of four mice to make them produce more dopamine, and blocked the neurons of four mice to make them produce less. It turns out that dopamine does seem to slow down the internal clock. Plus, the overestimation or underestimation only happened when the neurons were being manipulated, so it wasn’t because the mice were learning to adjust.

It’s important not to generalize the results too much. Dopamine is produced in lots of places in the brain, but the research focused on one area called the substantia nigra pars compacta. They chose this area because people with Parkinson’s disease have trouble judging time, and that the disease destroys this region.

In addition, the team was measuring dopamine indirectly, says Patrick Simen, a neuroscientist at Oberlin College who was not involved in the study. Directly measuring dopamine is hard, and the scientists were instead measuring the general activity of the neurons that release dopamine. This is usually pretty accurate, but sometimes factors other than dopamine cause a cell to become activated. Still, “this is an example of the incredible power of optogenetics,” says Simen. A lot of previous work measured dopamine throughout the entire brain, which gives us less useful information. “The strongest point is that they then went on and specifically found those neurons,” he adds. “They said, ‘let’s not just do a correlational thing, let’s actually perturb those neurons.’ It’s remarkable.”

Today’s Storystream

Feed refreshed 7 minutes ago Striking out

Andrew Webster7 minutes ago
Look at this Thing.

At its Tudum event today, Netflix showed off a new clip from the Tim Burton series Wednesday, which focused on a very important character: the sentient hand known as Thing. The full series starts streaming on November 23rd.

The Verge
Andrew WebsterAn hour ago
Get ready for some Netflix news.

At 1PM ET today Netflix is streaming its second annual Tudum event, where you can expect to hear news about and see trailers from its biggest franchises, including The Witcher and Bridgerton. I’ll be covering the event live alongside my colleague Charles Pulliam-Moore, and you can also watch along at the link below. There will be lots of expected names during the stream, but I have my fingers crossed for a new season of Hemlock Grove.

Andrew Webster1:05 PM UTC
Looking for something to do this weekend?

Why not hang out on the couch playing video games and watching TV. It’s a good time for it, with intriguing recent releases like Return to Monkey Island, Session: Skate Sim, and the Star Wars spinoff Andor. Or you could check out some of the new anime on Netflix, including Thermae Romae Novae (pictured below), which is my personal favorite time-traveling story about bathing.

A screenshot from the Netflix anime Thermae Romae Novae.
Thermae Romae Novae.
Image: Netflix

Welcome to the new Verge

Revolutionizing the media with blog posts

Nilay PatelSep 13
Tom WarrenSep 23
Has the Windows 11 2022 Update made your gaming PC stutter?

Nvidia GPU owners have been complaining of stuttering and poor frame rates with the latest Windows 11 update, but thankfully there’s a fix. Nvidia has identified an issue with its GeForce Experience overlay and the Windows 11 2022 Update (22H2). A fix is available in beta from Nvidia’s website.

External Link
If you’re using crash detection on the iPhone 14, invest in a really good phone mount.

Motorcycle owner Douglas Sonders has a cautionary tale in Jalopnik today about the iPhone 14’s new crash detection feature. He was riding his LiveWire One motorcycle down the West Side Highway at about 60 mph when he hit a bump, causing his iPhone 14 Pro Max to fly off its handlebar mount. Soon after, his girlfriend and parents received text messages that he had been in a horrible accident, causing several hours of panic. The phone even called the police, all because it fell off the handlebars. All thanks to crash detection.

Riding a motorcycle is very dangerous, and the last thing anyone needs is to think their loved one was in a horrible crash when they weren’t. This is obviously an edge case, but it makes me wonder what other sort of false positives we see as more phones adopt this technology.

External Link
Ford is running out of its own Blue Oval badges.

Running out of semiconductors is one thing, but running out of your own iconic nameplates is just downright brutal. The Wall Street Journal reports badge and nameplate shortages are impacting the automaker's popular F-series pickup lineup, delaying deliveries and causing general chaos.

Some executives are even proposing a 3D printing workaround, but they didn’t feel like the substitutes would clear the bar. All in all, it's been a dreadful summer of supply chain setbacks for Ford, leading the company to reorganize its org chart to bring some sort of relief.

Spain’s Transports Urbans de Sabadell has La Bussí.

Once again, the US has fallen behind in transportation — call it the Bussí gap. A hole in our infrastructure, if you will.

External Link
Jay PetersSep 23
Doing more with less (extravagant holiday parties).

Sundar Pichai addressed employees’ questions about Google’s spending changes at an all-hands this week, according to CNBC.

“Maybe you were planning on hiring six more people but maybe you are going to have to do with four and how are you going to make that happen?” Pichai sent a memo to workers in July about a hiring slowdown.

In the all-hands, Google’s head of finance also asked staff to try not to go “over the top” for holiday parties.

External Link
Insiders made the most money off of Helium’s “People’s Network.”

Remember Helium, which was touted by The New York Times in an article entitled “Maybe There’s a Use for Crypto After All?” Not only was the company misleading people about who used it — Salesforce and Lime weren’t using it, despite what Helium said on its site — Helium disproportionately enriched insiders, Forbes reports.

James VincentSep 23
Nvidia’s latest AI model generates endless 3D models.

Need to fill your video game, VR world, or project render with 3D chaff? Nvidia’s latest AI model could help. Trained on 2D images, it can churn out customizable 3D objects ready to import and tweak.

The model seems rudimentary (the renders aren’t amazing quality and seem limited in their variety), but generative AI models like this are only going to improve, speeding up work for all sorts of creative types.