Plastination versus Cryonics
gwern.net
gwern.net
I'm not worried about neurotransmitter levels or electrical activity, there are enough events during a normal lifetime where these can be severely compromised without any long term effects. What I am worried about, though, is the fine structure of "custom" proteins - meaning proteins that have been specifically generated by the brain to modulate the activity of one or more very specific neurons. It's not unreasonable to suspect that these serve an important role in long term memory formation and function.
I strongly suspect digitizing the connectome by itself may not be enough in the same way that saving the structure of an artificial neural network without preserving info about any weights, activation functions, and other parameters is not enough to reproduce the network later.
> by copying the digital data to many archives and formats online and offline. No such option is available to a cryonics brain unless it abandons cryonics entirely
How you judge this depends on what you're trying to achieve with cryonics. In theory, a destructive scan of a cryo-preserved brain should yield more and better data than that of a plastinated one. The question becomes: do we need that additional data or not?
I'd like cryonics to preserve brains until it becomes clear how to scan them adequately. By comparison, cryonic preservation is a relatively gentle process, whereas plastination imposes some heavy chemical changes on the brain to the point where it's entirely likely that too much information could be lost. The promise of cryonics lies not in a biological resurrection at a later date, but in giving researchers enough time to figure out how to actually do an upload. It may well turn out that plastinated remains are a sufficient data source, but contrast that with cryonics where much fewer doubts about the preservation of the necessary information exist.
Of course, cryonics is beyond problematic - it requires constant and costly upkeep. And more importantly, just a few days of political, economical, or technological instability can easily wipe out every cryo-preserved brain in existence. So it's clear this can't be a solution for the next few hundreds or years. It's a solution for the next few decades at best (until the first provider goes bankrupt).
The options, in a word, all suck.
Could you say why you think this? Were you convinced by the experiments done by the Cryonics Institute or Alcor? I haven't been able to contact a disinterested neuroscientist willing to take a serious look at that research.
>just a few days of political, economical, or technological instability can easily wipe out every cryo-preserved brain in existence
Political, maybe, if the the legal status of patients changes so that they are required to be thawed. But why economical or technological? I think I read somewhere that it would take like a month or something for the liquid nitrogen to evaporate enough for the patients to thaw.
During my time as a medical research minion I did some work on preserving tissue samples and even whole organs, including plastination and similar resin casts. What you need to be aware of is that, while the finished specimen look very good and life-like, they are radically altered on a biochemical level. All the water and lipids get replaced by resin. That requires soaking them in formaldehyde, acetone, and other chemicals before resin can even be applied. This process absolutely destroys proteins, in fact it relies on that. Also, the whole process takes days to complete, and during that time bio matter is actually being washed out and the whole structure is in motion. There is absolutely no question that information is lost here, in droves. If you believe plastination has a decent chance of preserving people's minds, you're operating under the assumption that the connectome itself will yield enough data for an upload.
Compared to that, freezing is, well freezing. Molecular motion almost ceases, so the most important aspect to gauge information loss in cryonics is what happens to the brain until it's finally cooled down. There are three main problems here. The first is the formation and shape of ice crystals which can (and do) destroy cells. This is a bit more relevant to in-vivo reanimation enthusiasts, because the physical shearing should probably be algorithmically correctable in a scan scenario. The second is the effect of the cryo fluid they pump into patients to prevent said ice crystals from forming, because it's also toxic to proteins. It's not as invasive as plastination, but it's still pretty bad. The third aspect is the time span from asystole to the halting of information loss. This might be a problem, but since current research indicates that a lot of ischemic brain damage is actually a cascade triggered by re-perfusion, there is cause for the assumption that anything up to a few hours might actually be fine.
> Were you convinced by the experiments done by the Cryonics Institute or Alcor?
I have to admit to only a passing knowledge of their in-house research efforts. Alcor's that is, I know next to nothing about CI. The problem is, they - nor anyone else for that matter - are not in a position to make any substantive claims about information fidelity beyond the continuing efforts to preserve the brain as faithfully as possible. A lot of their statements seem to focus on future viability of the tissue, and options for biological reanimation - but these are things I have no interest in (because I think it's both unrealistic and a bad deal). In fact, the last time I visited Alcor's site I couldn't find any reference to uploading at all, maybe I just missed it though.
> Political, maybe, if the the legal status of patients changes so that they are required to be thawed.
Yes, I agree. It's a massive taboo, ask any random person on the street and they'll be horrified. It's not difficult to imagine neuropreservation might get outlawed as soon as it looks like it might actually be feasible. In fact, we're seeing the same thing happening now with AGI. One can only imagine the public outcry involving bringing conserved brains back to life will be magnitudes larger than whatever will happen in respect to AGI soon.
> But why economical or technological?
By definition, cryonics companies have to operate on the fringe. That makes them especially vulnerable to disruption from relatively minor events. But even if they were as stable as, say a major bank: well, those fail, too. And if they're not going bankrupt, one might imagine a power outage lasting for months. Or some other infrastructure catastrophe that results in these companies being unable or unwilling to maintain services. Us western countries are kind of operating under the assumption that we're stable and eternal, which is an illusion.
That's why I said it's a solution for the next decades at best. During that time, if we really want to put resources behind it, we could theoretically figure out a destructive scanning -> uploading workflow (simulation can come later in principle). But if we're talking about biological reanimation... there is not even a tenuous time frame imaginable. We could easily talk hundreds of years until our nano tech is sufficiently advanced. And that's too long for two fragile companies to keep afloat in the face of economic crises, religious and cultural disapproval, incompetence and malice, accidents, disasters, and world events - any single one of which can wipe everything out.
>If you believe plastination has a decent chance of preserving people's minds, you're operating under the assumption that the connectome itself will yield enough data for an upload.
Ok I think this makes sense. I doubt that the connectome is sufficient.
>A lot of their statements seem to focus on future viability...
IIRC they talk about uploading issues under the code word "information-theoretic criterion of death", meaning that a preserved brain could be totally non-viable while still containing enough information to be uploaded; you're only dead if that information is destroyed, i.e. irretrievable "in principle" to an observer with full knowledge of human neurobiology and perfect scanning technology.
>future viability of the tissue, and options for biological reanimation - but these are things I have no interest in
Agree, I'm not particularly worried about viability. Side note: it is a lot easier to pitch reanimation than uploading to most people (not that it's easy either way).
>One can only imagine the public outcry involving bringing conserved brains back to life will be magnitudes larger than whatever will happen in respect to AGI soon
This being mildly hilarious, because the risks from non-human strong AGI are way way larger than those from reanimated humans or even uploads...
>But even if they were as stable as, say a major bank: well, those fail, too.
This isn't clear to me. Cryonics companies have a totally different business plan from banks. Each customer pays a large fixed cost up front before services are rendered, creating an endowment thing that should pay for them indefinitely. Specifically, they could make very conservative investments, such that it would take a world collapse to drive them under. In theory.
>hundreds of years until our nano tech is sufficiently advanced.
Hmmm... I think I would be pretty surprised if it took an unregulated nanotech industry more than 50--100 years to develop near-arbitrary capabilities. The roadblock to biological reanimation would be knowing what to specify to build, not the building part. (I agree that intuitively, scanning, if not actual uploading, should be much easier.)
>And that's too long for two fragile companies to keep afloat in the face of economic crises, religious and cultural disapproval, incompetence and malice, accidents, disasters, and world events - any single one of which can wipe everything out.
This is a pretty complicated question, but how do you think each of these risk factors would respond to broader adoption of cryonics? My guesses:
economic crises: significantly mitigated, because of economies of scale making it cheaper and overall scale making companies less vulnerable to variance. E.g. cryonics companies could build their own liquid nitrogen condensation plants, which are not that expensive at scale, I believe.
incompetence and malice: similar---at scale, companies could afford to defend against these
religious and cultural disapproval: unclear to me; how much of a threat would this be, and how hard would it be to get people to come around?
accidents: not much to do about this. Hypothetically, with extremely wide adoption of cryonics, there could be safety policy decisions made based on the calculation "How many accidents leading to non-cryopreservable brains will this lead to?".
disasters and world events: no help here. At scale, could slightly defend against tamer disasters with underground bunkers or something.
To be fair, this applies to any type of preservation/reanimation scenario.
> Specifically, they could make very conservative investments
As you said, in theory. In theory, so could banks ;)
> The roadblock to biological reanimation would be knowing what to specify to build, not the building part.
Exactly. Well, speaking from today's perspective, it's both. But yes, how to repair it and keep it alive would be a huge hassle, not to mention we simply don't have anything approaching this capability yet, even in principle. Not to forget, that at the end of this really long road, the problem has just been deferred by a few decades ;)
> but how do you think each of these risk factors would respond to broader adoption of cryonics?
No, I was talking about the other way around, since cryonics is not yet a factor in anything, it's susceptible to everything that may happen externally! We might disagree about the weight and probability of individual events, but I think we're clear on the fact that for quite a bit of time to come, cryonics is a vulnerable storage facility critically dependent on the infrastructure and benevolent indifference of our civilization - and not a concept that changes the course of anything (yet).
Right, I agree. I was wondering about evaluating the potential business or philanthropic benefits of interventions on cryonics; e.g. funding research on effectiveness of current protocols or on developing better protocols, seeding larger operations and capturing economies of scale, advertising/PR, lobbying for rights, etc. I haven't properly thought this through at all, but I suspect that there might actually be a pretty good philanthropic argument for some kind of preservation.
Society could save big on healthcare (not to mention the disutility of being kept alive to the bitter end) by preserving anyone whose health is in severe decline; anyone who has brain cancer, Alzheimer's, Parkinson's, etc.; anyone with imminently terminal diseases; and so on, all voluntarily of course. I believe end-of-life healthcare can typically cost tens of thousands of dollars, which is commensurate with preservation costs.
Further, it seems like I'd much rather save one person to live a long life (at the very least, thousands of years), than save two lives to live a standard life of ~50 more years. Though admittedly this depends on what you think your terminal values are, and also on difficult-to-estimate effects, e.g. the instrumental benefits of having more people alive now to help with morale or with doing stuff. And for obvious reasons this is uncomfortable to have to consider, and even more uncomfortable to actually propose as philanthropic policy.