34
votes
Frozen human brain tissue was successfully revived for the first time
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- Authors
- Joshua Hawkins, Andy Meek, Joe Wituschek, Jacob Siegal, Chris Smith
- Published
- May 18 2024
- Word count
- 399 words
I thought that in general, cryofreezing small cells and even larger samples like the 3mm cube, was already achievable. I'm guessing the big breakthrough is the prevention of cell death pathways via MEDY and the cell revival? But the biggest roadblock to Futurama style freezing is that a human body can't be frozen fast enough to preserve due to its size - how could MEDY be used to overcome this hurdle? I'm not much of a cryogenicist but I don't think you could just pump it into a body and freeze them from the inside out. A bath in it doesn't seem like it'd be fast enough either.
Nevertheless, I'm always excited to hear about advances in cryogenics! It's such an interesting field and the implications that perhaps one day we will cure all/most diseases is a nice bit of hope in an otherwise bleak world.
It's become routine to do rapid hypothermia down to < 14 °C within 5 minutes for cardiac surgery. ECMO machines can achieve flow rates ~ 4 - 6 L/min, so it's reasonable to expect that you could rapidly exchange blood for anti-freeze agents...
That being said, I agree and have doubts that you can perfuse all the human brain's microvasculature efficiently enough to preserve function in the absence of oxygen and prevent microcrystalline ice from forming. Brain ice cream?
Current state of the art, most cardiac patients on ECMO and deep hypothermia get "pump head" - transient or permanent neurological deficits after surgery, maybe due to microclots. Spouse could work after a month, but was still somewhat ditzy for 4 - 6 months.
I think this is the same news, or at least the same team?
On a more philosophical front, would you undergo a freezing medical treatment? Even assuming you're 99.9% certain you'll be brought back without side effects, and assuming your assets will grow with compound interest during that time, would you choose to "pause" your life and come back to a whole new world, one without your loved ones, where you will know exactly zero people and have zero friends and family, and one where your skills and knowledge are likely entirely obsoleted? What if your partner goes with you -- what would be the risks and are they justifiable to risk someone else's (quality of) life?
If you had asked me this four years ago, I would have said no. But since then I've completely upended my life, moved 5000 km to a city with no friends other than my partner, no job, new culture, etc. I don't have much contact with family so didn't even really have that to fall back on.
Fast forward today and I have more here, but if given the opportunity, I think I would undergo freezing. I feel like I'm more mature and less anxious than before that I could handle going into an unknown future. I guess it would depend on the age though. Freeze me now? No, I have a family and a lot to accomplish still. Freeze me around 70? Sure, at the least I'll get to see the future for a few years. It'll either be depressing or fantastic. Or I die on the way there, in which case at least everybody will have already been able to say goodbye and it's painless for me.
Thanks for the interesting thought experiment. Definitely made me look back on myself at the least and see how far I've come. Cheers!
Oh that's a good point -- if given the opportunity before expiring at a ripe old age maybe more of us would give it a go.... I wonder if that would be a more compassionate alternative to those seeking medically assisted suicide .... Roll the dice one more time so to speak....
My concern is if the you that is frozen is the you that awakes on the other side. I also wonder if we in some sense die every time we sleep, or even every time we lose focus. We don’t understand what consciousness is. It could be resilient but it could also be incredibly fragile.
Ooooh ~ kind of like, if we have teleporters, is the person coming through the other side really you?
(Long ramble follows)
Obviously I don't have any proof, but I wonder if we actually exist on a different kind of dimension, that our physical bodies + current consciousness are just the shadow, or a projection from the other side. When we sleep, the projection appears static to other people awake, meanwhile we're experiencing something else "in reality" or sort of a mix, which get remembered all weird when we the projection wake up. Sort of like watching a live stream and the audio/video pauses a bit while the streamer deals with their mom bursting into the room.
Near death experiences might be flickering a bit or has a dimmer on or the aperture closes slightly, and the image is interrupted briefly.
And then when we really die, the projection is no longer displayed in our dimensions, and other projected alive people lose the ability to reach us temporarily. And maybe we awaken to our true lives, in a sort of "well that was a good game, time to get up, stretch and eat dinner" type way.
Currently, you and I are just a projection. Just like how a 2d person cannot understand a 3d person, all of our dimensions are just a Flatland projection of reality. We can't fully understand who we truly are on the real side: we've just been told to be kind because some of us say there's a bit more after the end, or else be kind precisely because there's no more.
It might explain near death visions, how rarely we can speak with the dead, how they're (probably) aware of what's going on here, and how we can be resurrected etc.
I don't think this "you" that you are talking about exists at all. I don't think there is any more of an essence to the self than there is to the Ship of Theseus. Maybe something closer would be the belief that we die each moment and someone with our memories is born (a teaching similar to how some Zen Buddhists make sense of Saṃsāra), but this is still doesn't fully capture this rather ineffable concept.
From neuroscience, to philosophy, to first hand experiences, we can have very strong reasons to believe that this "self" that seems to persist from moment to moment doesn't exist.
On the materialist, physicalist front, Daniel Dennet has presented some thought experiments that demonstrate the absurdities that are entailed with believing in a self. That read is long but worthwhile. The book The Self Illusion: How the Social Brain Creates Identity by Bruce Hood is a commonly recommended perspective from neuroscience.
In Eastern philosophy, it's long been held that we can directly observe the fact that there isn't a self through introspection. This isn't something unique to mystics or something; atheist naturalists like Sam Harris also believe we can discover no-self through meditation [video]. While traditionally held to be ineffable, Sam Harris does a great job explaining in that clip just how meditation can lead to these insights. This is something I have been able to directly observe first-hand through specific contemplative and meditative practices (and I am far from a monk), and I think you might be able to as well with little training and practice.
Edit: Updated URL to correct clip
I've never been convinced by the arguments for identity through the "continuity of consciousness" approach. To my mind, the physical continuity view offers a more compelling framework for understanding personal identity, especially in addressing the challenge of identity persistence through periods of unconsciousness, such as sleep.
The physical continuity view proposes that personal identity is maintained through the persistence of the physical body, particularly the brain. According to this perspective, an individual remains the same person over time as long as there is an unbroken chain of physical and biological continuity, with the brain playing a crucial role as the seat of cognitive functions and memories.
In contrast, the continuity of consciousness view argues that personal identity is tied to the uninterrupted flow of conscious experience. Under this view, an individual remains the same person over time if there is a continuous stream of consciousness, often linked with memory and psychological states.
One major criticism leveled against the continuity of consciousness view, raised by philosophers, is the so-called "sleep problem" @teaearlgraycold alluded to. If identity were purely a matter of continuous consciousness, individuals would cease to exist every time they lose consciousness, such as during sleep. Upon waking, a new individual would emerge, lacking identity with the person who fell asleep. This implication is counterintuitive and problematic.
Viewing identity through the physical continuity view has a number of advantages:
The physical continuity view elegantly resolves the sleep problem. Since identity is grounded in the physical structure, particularly the brain, it remains intact during periods of unconsciousness. The brain continues to exist and function even when consciousness is temporarily suspended, thus preserving the individual's identity.
The physical continuity view aligns with our scientific understanding of biology and neuroscience. The brain's physical structure, including neuronal connections and patterns of activity, underpin our memories, personality, and cognitive functions. This provides a tangible, empirically grounded basis for personal identity.
While the physical continuity view focuses on the physical substrate, it can still accommodate psychological aspects like memory and personality. These elements are stored and processed within the brain's physical structure, so maintaining the brain indirectly maintains psychological continuity.
The physical continuity view can accommodate changes and growth within the same individual. Even as cells regenerate and the body evolves, the continuous existence of the brain and its patterns of activity ensure that identity remains intact. (In other words, it answers the question of how "I" am the same person that I was when I was 10 years old, despite the differences between me then and now.)
In medical contexts, conditions like coma, anesthesia, or other states where consciousness is disrupted do not imply the creation of new identities under the physical continuity view. The person remains the same because the physical basis of their identity—the brain and body—continues to exist, even if consciousness is interrupted.
In my opinion, the physical continuity view for personal identity offers a scientifically grounded and philosophically coherent account of what it means to remain the same person over time. By anchoring identity in the persistent physical structure, particularly the brain, it avoids the counterintuitive implications of the continuity of consciousness view, such as the notion that we die and are reborn every time we sleep. Moreover, it aligns with our empirical understanding of biology and neuroscience, providing a robust and coherent framework for understanding personal identity, even through periods of unconsciousness. That said, this is a complex issue that has been debated by philosophers for centuries, and reasonable perspectives can differ.
And maybe the above is just my psych degree talking.
Well, those aren't the only options. The problem with a physical continuity view is the ship of theseus. All of the matter in your body is regularly being replaced. From a physical standpoint, your body is not the same body as it was a decade ago, or a year ago, or even a day ago. Biological processes are exchanging oxygen atoms for other oxygen atoms, carbon atoms for other carbon atoms, and so on. Many cells die and are replaced with new ones on a regular basis. You could argue that the pattern those atoms are arranged in are what make a person, but if you were to make an exact copy of yourself, then those are clearly two different people. Only one of them is "you".
The most clear solution is that consciousness is simply an illusion caused by memory. You are an infinite number of individuals existing through time with only your shared memory linking you. If you made a clone of yourself with the same memory, it wouldn't share the same consciousness as you, and it wouldn't not share the same consciousness as you, because consciousness is an llusion created by having memory of being that person in the past, despite the fact that you merely shared similar pieces of matter, or configurations of that matter.
Asking the question "if you go through a teleporter, is it still you that comes out the other side?" Isn't really relevant, because "you" doesn't really exist. Anything you could think of as "you" is constantly ceasing to exist at every moment of every day, so using a teleporter that instantly kills you and creates a copy of you would, from a metaphysical standpoint, be no different than just existing for a couple moments.
I would argue that physical continuity bypasses the Ship of Theseus problem because of the "continuity" part of it. From one moment to the next, the physical substrate of my consciousness (i.e., my brain) passes along through time. I can talk about myself in the past because there is a causal chain linking 10-year-old me (and all of the constituent matter that made me up over three decades ago) to the version of me that is composing this post. The causal chain is the critical part — it doesn't have to be the exact same atoms present then and now. As long as the material in the structure passed from one moment to the next, we have continuity.
Transporters break the physical continuity if they operate Star Trek style (i.e., breaking the individual down, shooting all of their matter-energy across space, and then reassembling it). Continuity is broken. You die and a new version of you is built with the old parts.
Clones break physical continuity because, although their structure is identical to the original individual's, there is no continuity with that original individual's matter.
Thank you for your reply! This is really interesting stuff.
What does "personal identity" mean? Is it simply how I conceive of myself? Or is personal identity the same thing as "the self" or "ego" (as it used to be called in psych circles)? I don't think many would disagree that your social identity or your intuitions of the self are tethered to your physical body in some way. I think the contention is whether you have some sort of essential self that, say, dies if you go through a teleporter or if you get uploaded to a computer (i.e. lose this physical continuity.)
I also had some hangups on some of the perceived advantages of this view:
and 5. Why is the "sleep problem" a problem? I wouldn't think that a view having unpleasant implications should be a mark against its likelihood to be true.
and 3. it seems like perhaps these would apply in the case you upload your consciousness, assuming that the underlying neurology could be sufficiently emulated?
There may be conflicting intuitions here, but I don't see how accommodating change or growth would increase one's credence in this view. Even in common language, we often talk about how we aren't the same people we once were.
In the Ship of Theseus, one could argue that the identity of the ship is maintained as long as there is a physical continuity of the ship (one plank replaced at a time.) But it seems this continuity isn't some essential property of the ship, but exists in the minds of people who conceive of and talk about the ship. You could argue that it is within one's own mind of oneself that this continuity of the self takes place, but this seems to beg the question.
This may be my own ignorance, but this view seems just as arbitrary as believing the self is a continuity of consciousness. I'm still not sure why one should think that there is any continuity of the self at all (or even that the self exists).
It's a problem only if you maintain that you are the same individual that you were yesterday. Which I do. But I understand why someone else might not. (Particularly those who subscribe to continuity of consciousness.)
Fair enough. And maybe all of this is motivated cognition.
If I am to maintain that I am the same person I was yesterday, much less years in the past, I certainly cannot say that it's on the basis my present consciousness. That was, indeed, interrupted when I went to sleep last night. However, if I conceive of myself as my brain (which I do, independent of the question of continuity of identity), the continuity of consciousness question seems easier to explain. While I was sleeping, my brain was in a different state, true, but why does that mean that I did not exist until I became conscious this morning? (This is a rhetorical question. I understand why a proponent of continuity of consciousness might think this.)
Not in my view. There would be a copy of my brain somewhere, but it would not be my brain. If we are, indeed, unique entities (i.e., I am me and not you, anyone else, my desk, or my keyboard), then that presupposes that there cannot be two versions of us active at the same time. If a simulated version of my brain can be active at the same time that the physical brain that is responsible for this post is, then that must be a different thing. Furthermore, there was no point at which the matter in my head in its current configuration changed to become the simulation — the simulation was created by looking at that matter. It was not a transformation of it (in the way that thinking, growing, experiencing transform one's brain and therefore person/identity). If you hold up a piece of paper that you have drawn a triangle on and I painstakingly reproduce it on another piece of paper, you would not say that I have your original drawing. The identity of the drawing you created has been maintained and is independent from my reproduction.
Personally, I don't believe that, for an identity to be coherent over time, it must also be immutable. Certainly, there are plenty of philosophers who would reject this. For people in that camp, a thing is only a thing if it does not change, and, as soon as it does, it becomes a different thing. However, I believe that I am the same thing that is writing this sentence and I will be the same thing that clicks the "Post comment" button when I'm done.
At the end of the day, the only thing each of us can know with certainty is that we exist. But the nature of that thing is highly debatable. As a materialist, I believe that what I am is an extension of the processes of the jellylike substance in my skull called the brain. Additionally, I believe that things can change over time and still meaningfully be referred to as the same entity. In other words, I believe that I am a four dimensional object, and the continuity along the time dimension is how I can coherently say I exist despite the changes to myself.
Absolutely. No question. The future has more of the past within it, and more history would be excellent to be holding the hands of.
That's a very interesting take! Pessimistically, what if the future has more of the current bad? As a risk adverse person, what of the current good that might be lost? Is it the excitement of seeing more, and the confidence that whatever's present and lost will be preserved via history so you won't be missing much?
I wonder if it's because I'm primarily risk adverse? I would not take the deal myself and cannot imagine what could possibly entice me to do it at all :D how fascinating
The way you described it here, I was drawn to the thought of “hey, super deep down, isn’t that just the entire argument for conservative versus progressive?”
I don't understand why conservatives are the way they are and I don't understand how any of their policies could lead to what they say they want. :/
Presumably the school textbook version of conservatives are those who hold to a sort of older tradition and are resistant to change even at the risk of missing out on new opportunities, at least they are more concerned about holding on to what's currently there.
But in real life they don't preserve natural resources, they don't value hard faught for workers rights, they don't uphold the law when it comes to big corporate cheaters.....they ruin the things that make their present so darn good. I don't understand them at all
I suppose that's the difference between "conservatism" and "conservationism." The former is more concerned about preserving existing power structures and hierarchy than anything else. Conservationism is a threat to the status quo and is therefore likely to be opposed. "We never had to worry about how much gas we were burning in the past, so why should we start worrying about it now? This must be an invented problem." (I imagine this happening on a subconscious level. It's why climate denialism aligned with the Right because it justifies maintaining our current way of life.)
Ah, yeah I was definitely thinking of the platonic ideal of “conservative” in the old school definition.
Nowadays, I feel like any version of conservative is a lot closer to “unfettered capitalism at any cost, because one day I’ll totally be at the top of the food chain so I never wanna fight against it” if there’s a coherent idea at all.
Worth mentioning I also think that “progressive” is similarly no longer attached to the actual old-school definition of the word, but language use always changes over time, so I’m not going to try to say anyone is doing progressivism or conservatism “wrong”
My intense risk aversion leads me to want to avoid the oblivion of death, personally.
And any potential future where you would be revived has to be one that has the technology and interest to bother doing that.
Oh dude --- what if our frozen bodies get bundled and sold out to secondary and third tier scalpers like the stupid mortgage debt. And we are revived by slave owners looking to extract rather than to help. Gross. No thank you.
A society which has the technology and interest to revive the frozen head/bodies of the long dead seems like they could have easier methods of having manual labor performed for them. Like robots. Automation is already a looming issue now – I can't imagine it getting worse in the future.
On the other hand, maybe we never figure full automation out and they need our brains to operate robotic laborers. You never know.
But the oblivion of death scares me a lot more than that. So it would be a risk I would be willing to take.
What a fascinating perspective! I hope you find eternity :D
I think I read a character who did that in a book once, probably Peter F Hamilton (since that’s a majority of what I’ve read)? The character has already been leaping forward through time by the time they meet up with a protagonist. He just pops out for a few years, experiences the developments of civilisation for a bit, then pops back into stasis for a few decades before popping back out again later.
Also reminds me of Dr Who :)
There's another time travelling character who traverses backwards in time and meets the Doctor in reverse order, so that the last time they part is when one of them meets the other for the first time. Tragic love story 🥲
I haven't read it, but isn't that part of the premise for Vernor Vinge's 1986 novel Marooned in Realtime?
Also, this from elsewhere in the thread
One of my favorite books, Pandora's Star and Judas Unchained (double volume that form one long story, not two parts but one) by Peter F Hamilton, is set in a very technologically advanced 24th century human society.
One of the technologies of the setting is "Relife", enabled by their ability to both record/read/upload human memories as well as highly advanced genetic manipulation and growth technology that allows them to, among other things, clone human bodies. Everyone basically has a cranial implant that records memories, and they offload it every day or three or whatever to "long term" backup.
If anything happens, like death, those who have the means are relifed. Over about eighteen months their replacement body will be grown, and all their stored memories uploaded. After they "wake up", they go through a few months of physical therapy and they're off again.
People can also go through rejuvenation, which is the genetic de-aging of their existing body. They're "rewound" back to their late teens or whatever, and after a rehab period following the month or whatever the procedure takes, they have another five or eight decades to play with before it comes up again. The extremely wealthy will rejuvenate much more frequently, to stay actually youthful (rather than simply looking cosmetically youthful). The middle class basically pay into a rejuvenation insurance fund over decades, to ensure and insure they'll get to continue living when it's time (whether that's due to natural causes or a sudden accidental death).
The book does touch on how people in the society, a human collection of dozens of settled planets with a collective population that numbers somewhere in the low hundred billions, consider relife. Some of them hate it, hate the whole concept, consider it an abomination (and not just religious fanatics; some scientific minds dislike the break in continual chain-of-consciousness).
Others treat it exactly the same as going to sleep. Something happens, some accident or whatever, and you wake up in a new body. Same as you'd go to sleep and wake up the next morning.
Some fixate on what they "know" had to have happened, that they died. Since the memory updates aren't shown to be real-time, people will lose hours or maybe some number of days that weren't in their memory store. So few people actually know exactly what happened to their old self, even second hand. They just know they're young again, with a "memory gap", unscheduled which has to mean they encountered death. But someone who has a critical medical issue will usually have their final memories downloaded before they're put under for the rejuvenation that'll fix them back up good as new. It's accidents that have those gaps.
One of the characters dies, and goes through relife, and it fucks him up. Turns him into a neurotic wreck. Oddly enough, eventually the characters, including him, come to find out what happened to his old self. Which (plot stuff) had basically been vivisected by aliens.
Upon not just learning this, but being reunited (more plot stuff) with the continuous chain-of-consciousness old self (the old self had lived through (plot stuff), just the body had died), the character returns to normal. Isn't a neurotic mess anymore. The knowledge, even the grisly first-hand knowledge of his old body's death, the actual memories of being cut apart by aliens while helpless, he finds soothing and acceptable compared to what he'd been dealing with before; absolutely not knowing what had happened.
One of the things I've always found completely befuddling though, about the setting as depicted, is how they handle serious crime. You don't go to prison, you're put in suspended animation. They basically convict you, and then your body is shut down and you're stored medically. Unconscious.
This confuses me because I'm not sure how I'm supposed to see that as a punishment? Like, today's prisons you can't leave. You have to live through that experience. You're trapped, you're controlled, and you have little to no say over anything in or involving your environment. Books and anything else, you're at the mercy of the prison authorities as to whether or not you get them. Or get to keep them.
Meanwhile, in The Commonwealth (the society depicted in the books), you're just basically switched off for the duration of your sentence. After the years roll by, they wake you back up and your time is done.
Except now you're in the future. Further, the future you technically didn't have to pay to get to. Normal law abiding people in The Commonwealth have to maintain their rejuvenation insurance to be assured of getting to the future. Plus, you know, all the other stuff that goes into life like shelter and food and all that. Day by day, paying for it, arranging for it, everything. After you've lived "a life", when it's time, you rejuvenate and keep going. Again, on your dime and as something you have to arrange for.
Meanwhile, a prisoner gets to basically just time travel into the future for free. The Commonwealth doesn't even do any creepy memory modifications or personality manipulation or mind control or anything of the sort. The way it's shown, you just get tried, convicted, suspended, woken up, and presto it's now decades later.
Technology and everything else will march on. In the follow up trilogy that takes place in the same universe (just ~1100 years or whatever later), you see humanity has effectively turned into magicians. Matter manipulation technology at the atomic level, teleportation, organic "cybernetics" that turn you into a superhero, that kind of thing.
It's just always puzzled me, trying to figure out why getting a free ride into the future would be bad, would be a punishment. What's the problem? You don't have control? Well, you wouldn't most of the time anyway unless you were super wealthy. Life happens and it's not like most of us have any actual control over what's going on around us, so I don't consider that a very compelling argument.
You lose access, time with, people you know? Is that supposed to be the big penalty, that family and friends will move on? But it's not like they'll die, odds are greatly in favor of them still being alive whenever you "get out" of suspension. They won't even be wizened little elderly people with age ravaged bodies; they'll be who they were when you last saw them.
So there's not even the gut punch you'll sometimes see in such stories (Aliens comes to mind, so does Demolition Man) where revived/awoken characters have to grapple with knowing a descendant lived and died while they were suspended.
Like, right now, if I could suspend for, say, a century? Hell yes. Right now has a ton of limitations. Most of them are artificially imposed, and just about all of them suck. Getting to skip ahead, and maybe come out in a world where those specific annoyances aren't annoying anymore? Sign me up.
Of course, "the future" doesn't mean "paradise" or anything. People are people, and stuff that's stupid now will just be replaced with new stupid. But at least it would be new. And if nothing else, I guess I could just go resume tossing bricks through store windows or whatever until they suspend me again. Do not pass go, just go straight to suspension and try again a few decades later.
Oddly enough, the same author (Hamilton) had a character in another story's future society setting that was "leapfrogging" through time. He'd self-suspend himself for a century or so, then wake up and bomb around for five years before suspending again. Obviously the narrative in those books (Neutronium Alchemist) took place during one of that character's awake periods. I always though that sounded completely awesome, and that society wasn't even shown to have immortality tech IIRC.
The follow up trilogy brings back a character from the first story. Well, a number of characters reappear since immortality is a thing in that setting, but one in particular hadn't had a smooth ride between the first and second stories. They'd ended up being put in suspension for most of the time period between the first story and the follow on. Basically a big chunk of a millennia before being woken back up.
The narrative doesn't go into a slice of life examination or anything, but that awoken character isn't shown to have been kicked to the curb and left to drown and starve penniless in a heartless future. It's not explicitly covered, but you get the impression the society offered him a bit of help to get restarted as a proper citizen. There's retraining so they have a modern skillset, and when we first touch base we see they're living just fine. No sign they'd "lost" something like six or eight hundred years of life.
Immorality is something I think humanity will have to have in hand, and further live with for probably several centuries at a minimum, before we begin to come to terms with it. If such a thing is even possible, either immortality or coming to terms. But it would be interesting. And can't be much worse than what we have today, with the planet sort of moving towards another global war.
Maybe that's something immortality would fix; the loss of collective memory. Because it hasn't been lost on me that just as the longest lived people who actually fought in or lived through World War II have begun to finally die off (folks who've made it to ~100), and we're left with no actual living witnesses to it, it's starting to look like we're headed for a third global war. Coincidence? Maybe, but maybe once the stories become mere history people are more likely to forget just why we'd learned what a horrible idea it was the last time?
If we could suspend and wake back up after all the fighting, I'd sign up. Better than living through one I'd wager.
Wait, this is unfamiliar to me, and I thought I’ve been reading most of Hamilton’s stuff — can you tell me the name of the book(s) that’s set in the same universe following on from Night’s Dawn trilogy?
I was referring to Void as a followup to Commonwealth, not that there's a followup to Alchemist. Honestly, I'm not even much of a fan of Alchemist. The whole dead zombifying the living aspect is just super creepy to me, and the universe itself isn't nearly as interesting as the Commonwealth is to me.
Ah, right, that makes a lot more sense to me! I just finished the Void series and the only other one I haven’t finished yet is Greg Mandel (currently half way through) and Salvation which is on my shelf ready to go, but I haven’t picked it up yet. I was wondering if Salvation series was going to be tied into the Night’s Dawn series somehow.
I definitely agree that the Commonwealth sagas are much more compelling, I wonder if it’s because Hamilton has become a better writer over time or if there’s something to the setting itself that’s pulling me in? It took me a while to like the blending of sci-fi and fantasy, but I’m definitely sold on it now.
I have some experience with brain cell culturing (though, about a decade past, so I tried to read a couple more modern sources to make sure my info isn't completely ancient).
Freezing cells (in single-cell suspension) generally is long established. But, different types of cells can be more/less difficult to cryopreserve, and neurons are particularly tricky to work with. I can say from experience, at least with culturing, there's a huge degree of finesse and craft needed to be successful that's impossible to convey in the methods of a research paper. Take a look at this commercial description of Gibco-cryopreserved neurons (Gibco is a very common brand in cell culturing): They advertise that 50-80% of cells remaining alive after thawing is a huge success compared to competitors.. Also bear in mind, unlike other cell types, you only get the neurons that live, they don't replicate and make more in culture (assuming we're talking neurons, and not neural stem cells). Another consideration is, because mature neurons have incredibly complex, fragile shapes, they often need to be cultured from either extremely juvenile neural cells or from neural progenitor cells (i.e., stem cells that can be manipulated to turn into neurons).
In terms of cryopreserving three-dimensional clumps of different types of cells: Now you're trying not only to keep single cells alive but different types of cells while also preserving their structure. I don't have any first-hand experience here, but it's a rather recently advancing area (e.g., in this review most references are within last 7-8-ish years; PDF accessible via Google Scholar).
I think it's worth mentioning that most of the experiments in this study (it's open access) were conducted on organoids (single-suspension stem cells cultured into 3d clumps that then could differentiate into different cells types). In the one experiment on actual tissue, I felt like the authors obfuscated the results a little. They note "most neurons and astrocytes in MEDY-cryopreserved brain tissue were well preserved" [compared to normal, non-cryopreserved tissue]. What they don't mention, but clear in Fig. 6K and L, there was a 10-percentage point drop in mature neurons (NeuN-positive cells) from the non-cryopreserved tissue vs. the 'normal' tissue. I say this not to detract from the study, just to convey that result more realistically. A 10-percentage point drop in viable mature neurons (from 40% in normal to 30% MEDY-cryopreserved) may be fine for research purposes. Probably not so much if you want to thaw grandpa.
Related/not: I just finished reading the book "We are Legion: We are Bob" that considered a lot of the ethics of this kind of thing (although more in line with artificial consciousness via "stored" neural information). Would highly recommend the read.