Scientists froze slices of mouse brains at -150°C for up to a week. After warming them up, the slices showed almost normal electrical activity, New Scientist reports. The New Scientist article is paywalled but PDFs of the entire magazine issue are easy to find.

A preprint published in bioRxiv describes the methods and results of this study. Popular Mechanics covers the story.

This discovery could help us learn how to cool and revive whole brains someday. We might use this for cryonics and suspended animation during long space flights. Research leader Alexander German feels cautious excitement about the idea.

Freezing living tissues is tricky because ice crystals form and damage cells. Cryopreservation means freezing tissues without harming them. Ice crystals tear apart molecules and blood vessels as they grow.

Some animals, like the brown tree frog, make cryoprotectants. These are special chemicals that stop ice from forming. This helps them survive cold temperatures. In the 1980s, researchers Greg Fahy and William Rall used cryoprotectants on mammal cells, with encouraging but preliminary results.

Memories might survive in a whole frozen brain

Now, German’s team tried new mixes of cryoprotectants. They cooled mouse brain slices to -196°C with liquid nitrogen. After a week at -150°C, they warmed the slices. Tests showed the slices worked like unfrozen ones. Synapses, which connect nerve cells, stayed intact. This might mean memories might survive in a whole brain. German says more tests are needed to be sure.

Other studies revived rat hearts in 2021, livers in 2022, and kidneys in 2023. German believes this could work for whole brains and even entire rodents. He thinks humans could be cryopreserved too.

Other experts doubt this will work for whole brains soon. But even if it only works for slices, it’s helpful. Brain slices from surgery could be stored and studied later. This could improve research on brain diseases and treatments, Fahy says.

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