Come with me if you want to live. – The Terminator

'Close enough' only counts in horseshoes and hand grenades. – Traditional

After 10 years of research my company, Nectome, has created a new method for whole-body, whole-brain, human end-of-life preservation for the purpose of future revival. Our protocol is capable of preserving every synapse and every cell in the body with enough detail that current neuroscience says long-term memories are preserved. It's compatible with traditional funerals at room temperature and stable for hundreds of years at cold temperatures.

The short version

We're making a non-Pascal's wager version of cryonics.
Our method is an end-of-life procedure for whole-body, whole-brain human preservation with the goal of eventual future revival.
Preservation occurs after legal death.
Even without the near-term possibility of revival we can be confident that preservation actually works.
We preserve the whole body, including the brain, at nanoscale, subsynaptic detail. We are capable of preserving every neuron and every synapse in the brain, and almost every protein, lipid, and nucleic acid within each cell and throughout the entire body is held in place by molecular crosslinks.
It works by using fixative to bind together the proteins and cryoprotectants to prevent ice over the long term, and cold temperature to extend the stable preservation time period to centuries.
We've won the Large Mammal Brain Preservation prize from the Brain Preservation Foundation for preserving animal brains, which involved examining the preserved synapses across many regions of the brain.
Unlike previous cryonics methods that required extremely low-temperature liquid nitrogen coolant, our method is stable for months at room temperature and compatible with traditional funeral practices.
Biology imposes a strict time limit for successful, real-world preservation: we've found that if you want high-fidelity preservation, you must start the procedure within twelve minutes post-mortem. This means that all of our procedures are planned, and we do not offer emergency preservation.
We don't yet have the technology to revive someone who has been preserved, but we do have the evidence to say that we preserve all the information that would be needed for revival.
We're agnostic towards revival methods: uploading, biological revival, or any other sort, and we think that regardless of method, our starting point offers the best chance.
We're offering limited pre-sales now.
We'll be hanging out in the comments section for the next several hours to engage with your questions. We also have a Manifold poll, embedded near the bottom, about what next post would be most valuable to the community.

"Maybe" isn't good enough for me

A brief refresher: traditional cryonics uses two things to preserve people: cold to preserve the brain, and cryoprotectants to prevent the catastrophic damage caused by the formation of ice crystals. Unfortunately, cryoprotectants themselves crush neurons through osmotic effects, damaging the structure of the brain.

Traditional cryonics works in "emergency mode", where cryonics organizations are first notified after one of their members dies, then attempt to preserve them in response, often with a delay of hours or even days during which time the brain is damaged. Traditional cryonics takes place after a "natural death" in most cases. However, natural deaths take a long time, and brain damage sets in well before legal death. For me, all this damage calls into question whether memories are really preserved.

The strongest argument for traditional cryonics is that any kind of preservation is better than nothing, and that cryonics is "not a secure way to erase a person". This is true enough as far as it goes: certainly, no physical process truly "destroys" information. What we really care about with preservation is how accessible the information is and whether it's still contained within a person's preserved body or not. This is a really important question for me, so I ran the experiments myself and was not impressed.

I set out to build something that feels to me like less of a Pascal's Wager. I want a preservation protocol that, according to our best theories of neuroscience, does work. At the same time, I wanted to craft an experience that normal people would be comfortable with – I want our parents and grandparents to be willing to come into the future with us.

The result is a protocol that my company, Nectome, has spent the past ten years developing. After years of experiments in the lab and in the field, learning about the complexity of end-of-life biology, and after refining our protocol to make it robust and repeatable for real people in real-world clinical settings, we are now ready. We've developed a whole-body, whole-brain, human end-of-life preservation protocol based on neuroscience first principles. We are capable of preserving every synapse and almost every protein, lipid, and nucleic acid throughout the whole body. Brains are connectomically traceable after preservation^[1]. Our preservation is so comprehensive that current neuroscience theories imply it preserves all relevant information necessary for future restoration of a preserved person.

Further reading: "Brain Freeze", Aurelia Song, Asterisk Magazine

A preservation protocol that's worthy of us

Cryonics in my opinion has had two main issues holding it back, both of which we've solved.

The Quality Problem: The first issue is that traditional cryonics methods haven't been shown, even under ideal circumstances, to preserve brains well enough that they're connectomically traceable afterwards. We solved this issue by adding crosslinks to the mix. In 2015 I published a protocol in Cryobiology using crosslinks, cryoprotectants, and cold to preserve animal brains with near-perfect quality. In 2018 I won the Brain Preservation Foundation's Large Mammal Brain Preservation Prize using aldehyde-stabilized cryopreservation.

The Timing Problem: The second issue is with the emergency response model of traditional cryonics. Doing preservations as an emergency response and after a natural death causes damage independent of whatever protocol you're using. Severe damage happens before legal death as a result of inadequate blood circulation and partial brain ischemia. Even more damage occurs post-mortem due to cell autolysis and other degradation pathways. Shortly after death it becomes almost impossible to completely perfuse brains (this is the problem that ended up giving us the most trouble).

We worked from 2018 to 2025 trying to solve the Timing Problem to our satisfaction, and eventually succeeded in creating a protocol that gave comparable results to our ideal laboratory version, but could be used in the real world. There's a cost, of course, for this quality: we've learned that preservations must start within twelve minutes post-mortem after a quick respiratory death. That means preservations have to be scheduled in advance, and they have to be done in conjunction with medical aid-in-dying (MAiD).

The images above are taken from the BPF's Accreditation page. On the left, you can see the pig brain which I preserved, winning the Large Mammal prize. The cellular structure is intact and it's easy to trace the connections between the neurons. The right-hand image shows the damage caused by traditional cryopreservation, even under ideal circumstances. Real preservation cases are far worse due to pre- and post-mortem brain damage. Maybe a superintelligence could reconstruct the structure – but it's unclear whether the information to do so remains.

We've published a preprint of some of our most relevant experiments on bioRxiv, where we show we can get the same excellent quality we got in 2018, except now under realistic end-of-life conditions. We've also performed experiments which have undergone independent evaluation; we'll discuss those in a subsequent post, but for now here's a sneak peek:

This is a section taken from a rat brain preserved 5 minutes post-mortem in a manner that's consistent with the surgical time we can achieve with pigs. All axons, dendrites, and synapses pictured are connectomically traceable. After preservation, we stored this brain at 60°C for ~12 hours before imaging! **Click through for a "Google Earth"-style presentation of the whole slice, which is around 5 GB of data**.

What does preservation look like for you?

In order to work within the limits of biology, Nectome does preservation exclusively as a planned, scheduled procedure. We do not offer an emergency response model because there is no emergency response model we could do which would meet our standard. To receive a preservation which meets our standard of care, terminally ill patients must plan in advance, travel to a preservation center, and use medical aid-in-dying.

Our business model is different than traditional cryonics: we sell transferable preservations in advance instead of using a membership + insurance model. When you buy a preservation, you buy the ability to designate a person of your choice (including yourself) to be preserved. We will then work with that person to understand their preferences for preservation, the most important of which are:

Chain of custody: In the event of an impending loss of custody of your preserved body, such as major government changes, what do you want us to do? Do you want us to cremate you, or do you want us to do our best to make sure you stay preserved, even if it means we will no longer be in control of what happens later?
Method of revival: Do you want to restrict which revival methods may be used to restore you in the future? Nectome is officially agnostic on revival method. Do you want to restrict the use of destructive uploading to revive you? Wait for 100 years and then only do it if there's not another option? Do it but only after 1,000 people have done it before you and liked it? This is a very personal question and we want to get as much information in advance so we can respect your choice.

When it's time, we'll invite clients and their families to stay for a few days at a beautiful preservation center in the peaceful Oregon foothills, where they can spend time together, say their goodbyes, and participate in any farewell ceremonies they choose. After the procedure the preserved person is stable for months at room temperature, allowing for a standard open-casket funeral in their home state.

In the long term, preserved people will be maintained at -32°C. In all cases, they will remain in a whole-body state; Nectome never does brain-only storage.

Conclusion

I've introduced here a new kind of cryonics which I hope will move the field away from Pascal's wager and towards a rigorous discipline that will become a mainstream part of end-of-life care.

We can preserve people following MAiD with a protocol that can preserve every synapse and virtually all biomolecules, throughout a person's entire body. That's good enough that our current theories of neuroscience say it does work to retain sufficient information about a person such that they could be restored with adequate future technology.

We know that our protocol doesn't serve everyone, and we hope that continuing scientific and legal advances will allow us to preserve an increasing fraction of people. But it serves many people (most people don't die suddenly!), and we want to offer something that verifiably works, not a shot in the dark.

We don't yet have the technology to revive someone who has been preserved, but we do have the evidence to say that we preserve all the information that would be needed for revival.

Over the next posts in this series, I'll go over the information-theoretic basis we use for preservation, the reasons why it has to be an end of life protocol, our hope for the long-term future, why this all still makes sense even given short AI timelines, and several other things.

In the meantime, below you'll find several of the links in this post and descriptions of why you might want to read them.

I want you to live

Why did I spend the last 10 years of my life on this project?

We all start out life born in twin prisons: the gravity well of the earth, keeping us on a tiny speck of dust compared to the wider universe beyond, and the limit of our natural lifespan, confining us to a tiny sliver of the universe's grand history.

When preservation becomes a new worldwide tradition, even before revival is technically possible, it will expand peoples' personal planning horizons. I expect to see people start 1,000 year projects believing they will personally see the end result. I'd like to see what they choose to make.

I believe that Preservation is for everyone and that the future loves you and wants to welcome you back with a desire that can't be conveyed with words on a page. Let's get there, together.

Our whitepaper detailing how preservation will work and why we think it works. https://nectome.com/personal-preservation
Our work published last week preserving pigs under real world end-of-life conditions. https://www.biorxiv.org/content/10.64898/2026.03.04.709724
Our paper describing the technique that won both Brain Preservation Prizes: https://www.sciencedirect.com/science/article/pii/S001122401500245X
Brain Preservation Prize large mammal announcement: https://www.brainpreservation.org/large-mammal-announcement/
"The Case for Glutaraldehyde" an analysis of why fixation likely preserves sufficient information about a person for future reconstruction: https://nectome.com/the-case-for-glutaraldehyde-structural-encoding-and-preservation-of-long-term-memories/
"Brain Freeze", an article in Asterisk Magazine talking about the problems facing traditional cryonics: https://asteriskmag.com/issues/10/brain-freeze
The BPF's plan for accreditation. Nectome hopes to become fully accredited and begin preserving people this year. https://www.brainpreservation.org/accreditation/

I'm looking forward to talking with you all in the comments. I'll be around for a while once this post is up. There's a lot to discuss! Vote for what we should cover next:

"Connectomically traceable" means that each synapse can be physically traced to its originating neurons in a gigantic 3D map. For more info, I like Sebastian Seung's TED talk. ↩︎