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A Mammal’s Brain Has Been Cryonically Preserved and Recovered

A team lead by a researcher at MIT says it has thawed a cryonically-frozen rabbit brain without causing structural damage.

A big thing just happened in the world of cryonics, and it has nothing to do with Ted Williams' permafrozen remains.

Officials from the Brain Preservation Foundation, a nonprofit that funds brain preservation research, just awarded its five-year old "Small Mammal Brain Preservation Prize" to 21st Century Medicine.

In a recently published article in the journal Cryobiology, the team, lead by MIT graduate Robert McIntyre, announced it has cryonically frozen the brain of a small mammal and recovered it in near perfect condition. According to the Foundation's press release, "it is the first demonstration that near-perfect, long term structural preservation of an intact mammalian brain is achievable."


Scientists in the cryonics community have long sought better ways to preserve the collection of the brain's more than 86 billion neurons and the map of their synaptic connections. By preserving the brain's neural structure, it's hoped that long term memories can be recorded for later recovery or even uploaded to machines. The ultimate goal is to create a sort of medical time travel where an individual could store their identity so that future society may re-animate them once technologies have sufficiently advanced. It's basically the plot of the first 20 minutes of Austin Powers, but for real.

"The next step for cryonics research is to demonstrate these techniques work on larger animal brains"

The promise of such a technique has been out of reach to scientists since the chemical process of preservation has proven far too damaging for any brain's future revival. The challenge comes from today's standards of cryonics freezing, which according to officials at the foundation, causes massive dehydration in the brain, squashing the neural connections and rendering it useless for imaging. That's why 21st Century Medicine's achievement is so exciting.

McIntyre's team reportedly demonstrated the ability to cryonically preserve the neural connections inside an intact rabbit brain, and fully thaw the thing back. The approach used what's called an "Aldehyde-Stabilized Cryopreservation" protocol, meaning the researchers dispersed a collection of chemicals through the vascular system of the brain which fixes the neurons in place, then converted it to a glasslike object by cooling it to -210 degrees F (-130 C) for long term storage. Later, the brain was rewarmed and the cryoprotectant chemicals were removed.


Judges at the Brain Preservation Foundation then used traditional electron microscopy to image hundreds of brain regions to ensure that the synaptic connections in the rabbit brain remained undamaged.

"Every neuron and synapse looks beautifully preserved across the entire brain," Kenneth Hayworth, president of the Foundation and a prize judge, said in the announcement. "Simply amazing given that I held in my hand this very same brain when it was frozen solid."

"This is a big deal," John Smart, co-founder of the Brain Preservation Foundation, told Motherboard. "It's the first time that we have a procedure that can protect everything neuroscientists think is involved with learning and memory. Given the results announced today, it seems to me that long-term memories are successfully preserved by this technique. This is not yet certain or universally agreed, but seems highly likely from my position."

The small brain challenge had two submissions. The other was from Shawn Mikula from the Max Planck Institute of Neurobiology in Germany, who also submitted a promising candidate to the small brain challenge. His approach used a form of plastination, a way of turning the brain into a plastic-like block, so that it could be preserved at room temperature.

The promise of a deathless future at the heart of cryonics research presumes that immortality may be achieved by uploading our neural structures into machines. The technologies are advancing toward a world where we might see communities of future-people living inside their computers. It is still unclear, however, if memory preservation reaches far enough into the realms of personality to preserve the "who you really are" aspects of a person.


"As to knowing that these techniques capture 'the rest of the person' including personality and consciousness: We will get there, but more slowly," Smart said. "Consciousness is still not definitively understood in neuroscience, though neuroscientists are beginning to offer promising materialist models."

At this point, if someone preserves the neurons in their brain, there's no guarantee that it's enough to preserve their "soul," whatever that may end up meaning.

The next step for cryonics research is to demonstrate these techniques work on larger animal brains, and so the Foundation has an unclaimed prize out for the first team who can preserve a pig brain, or one with similar size. That breakthrough may not be far off, as 21st Century Medicine has already submitted a candidate that is now under review. It's the only one to submit so far to the larger brain challenge.

The weirdness of preserving your brain for a future era could prove far too alienating for widespread adoption, but Smart hopes that today's announcement will stimulate a renewed sense of interest for those who wish to sign up for preservation at death.

"It's a highly personal decision, but we believe that if these techniques can be validated in large animals, we should be able to make them increasingly available in society," he said. "I think the question of preservation will be one of the more valuable social conversations we can have."

"In short, this is a very exciting time to be alive," he said. If things keep moving, that 'time to be alive' part may last a while.

Correction: An earlier version of this story said standard cryonics freezing renders the brain useless according to the Brain Preservation Foundation; in fact, what they said was that the procedure renders it useless only for electron microscopy imaging.