Here’s an analysis of the respective benefits and drawbacks of Plastination vs. Cryonics in respect to neuropreservation: http://www.gwern.net/plastination
However, a part of the argument is missing. Namely how absolutely awful plastination is for any purpose that needs to feature the preservation of protein structures. I believe people have been mislead by how awesome the specimen look to the naked eye and microscope that they forget it’s an aggressive multi-step extraction and replacement procedure taking days to complete. The overall biochemical information loss is in fact more severe than just letting the organs soak in formalin for a few decades.
current plastination techniques sufficing to create connectomes, but what does it miss?
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.
The Real Difference between Cryonics and Plastination, from an Information Theoretic Point of View
Plastination: 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.
Cryonics: 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.