How placebos ease pain in the mouse brain

Hello Nature readers,
Today, we find out what happens when AI models learn from AI-generated text, learn about new clues to how the placebo effect works and discover that memory for music doesn’t fade with age.

AI fed AI-generated data spews nonsense

Training successive versions of artificial intelligence (AI) models on text generated by the previous iteration quickly leads to the system producing gibberish. This collapse happens because each new model learns not from reality, but from the previous model’s prediction of reality, with errors getting amplified over time. Even before complete collapse, learning from AI-generated texts means less common information in the dataset gets ‘forgotten’. “The message is we have to be very careful about what ends up in our training data,” says AI researcher and study co-author Zakhar Shumaylov.

How placebos ease pain

In mice, the placebo effect seems to activate parts of the brain typically associated with movement and coordination. The animals were conditioned to expect pain relief, mimicking how some people can get pain relief from taking a sugar pill they believe contains a drug. Analysis of the mice’s neurons in the active regions revealed that 65% had opioid receptors — the same kind that are activated by powerful painkillers. The research “provides a new target that we can look for in human studies”, says neuroscientist Tom Wager.

Music memory is age-resistant

Eighty-year-olds can identify tunes just as well as teenagers can. “You’ll hear anecdotes all the time of how people with severe Alzheimer’s can't speak, can’t recognize people, but will sing the songs of their childhood or play the piano,” says music scientist Sarah Sauvé, who tested how well roughly 90 healthy volunteers, aged 18 to 86 years, could recognize themes across three pieces of music. Musical memory and recognition did not vary with age, even when the music was unfamiliar.

Protect scientists’ thinking time

Digital devices and instant messaging have enormous benefits, including speeding up research. But they are also a distraction, argues a Nature editorial. In his book Slow Productivity, computer scientist Cal Newport says that having to concentrate without interruptions is key to high-quality work. More studies should explore the impact of lost concentration time on science, the editorial suggests, and whether tools to automate routine tasks could free up more thinking time — or have the opposite effect.

The climate scientist turned whistleblower

“I don’t want to be here, but if not me, who?” asks climate scientist Virginia Burkett, who is demanding better policies to protect US government scientists against political interference. In a lengthy whistleblower complaint, she is seeking an investigation into “abuse of authority and gross mismanagement” under former US president Donald Trump. Burkett says that, in 2017, she was demoted after criticizing the government for dismantling climate research programmes, cutting science budgets and attempting to water down an influential climate report. “This is not about what happened to me, it’s about what could happen to others,” Burkett says.

Did complex life start on Snowball Earth?

More than 500 million years ago, the globe was covered in glaciers and sea ice. This Snowball Earth seems hostile to life, yet it was probably during this time that single-celled organisms first evolved into complex, multicellular creatures. One possible answer to this conundrum: when seawater gets colder, it gets more viscous, so individual cells could have started to stick together to move through it more efficiently in search of food. In experiments with modern single-celled green algae, cells living in viscous gels formed coordinated groups to keep swimming.