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How to approach the problem of brain preservation?

by lsparrish
Tags: brain, preservation
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lsparrish
#1
Aug13-14, 05:38 PM
P: 2
Although we have nerves throughout the body, a person's essential personality and memories are thought to be stored more or less completely in the brain. In theory, you could transplant a brain into a new body, and the individual who would awaken would be the one whose brain is used. It would be more of a "body transplant", in a sense.

This has the interesting consequence that an individual could be preserved after multiple organ failures, if only their brain could be prevented from losing its memories irrecoverably at the moment of death, and transitioned to a stable state. Even if the preservation mechanism were to turn the brain into a completely inert substance devoid of ongoing consciousness, the hope of reanimating them and restoring consciousness would remain for as long as scientific progress continues and their storage is maintained.

There are several general approaches to rendering living tissue inert over a long period of time: plastination, dehydration, and cryopreservation.

Although human cells can tolerate dessication under some conditions (http://www.ncbi.nlm.nih.gov/pubmed/11578120), this is unlikely to translate to organized brain tissue. Not only would there be extreme morphological distortion and cytostructural damage, the concentration of proteins within cells in the absence of protective sugars like trehalose tends to be harmful. Lyophilization (freeze drying) has similar problems, although it is not as harmful.

Plastination (replacing the water with a resin or plastic that solidifies at a higher temperature) for EM tends to rely on formalin fixation, which renders cells nonviable. So we would have to be very confident that we can make use of the raw morphological data, if this approach were to be used on a living patient. More problematically, fixing and plastinating something as large as the brain has never been done successfully.

Cryopreservation has problems as well. If low concentrations of cryoprotectants are used, ice tends to form, as heat cannot be removed from a large organ like the brain fast enough for supercooling to the glass transition temperature. High concentrations must be used instead. This renders cells nonviable, given realistic cooling times. Nonetheless, it does provide a route to morphological preservation (considered the current best case scenario in cryonics).

Some progress has been achieved in reducing the toxicity of cryoprotectants, and reducing the concentration required. The osmolar concentration is what determines freezing point depression, however cooling below the freezing point is possible to some degree. Ice blockers can be used for this. The tissue being vitrified may also be placed under high hydrostatic pressure as a way to prevent ice formation. In 2004 a rabbit kidney was reversibly vitrified, and implanted successfully. (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2781097/)

It seems strange to me that there are not more people interested in neural cryobiology, particularly the effects of high-osmolality vitrification. It seems that most interest in this is fueled by cryonics/transhumanism in some fashion, e.g. the Brain Preservation Foundation prize. Nonetheless, it is an empirical field where observations regarding viability and morphological preservation can be made.
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DiracPool
#2
Aug14-14, 04:04 AM
P: 611
Is there a question here other than, perhaps, the title of the thread? It looks to me as though you've done your research and are perhaps more of an authority on the subject than most people.

That said, it is a very interesting topic that is in an early stage in its development and has all sorts of interesting consequences surrounding it. Obviously, the solution at the end of the day isn't going to be as simple as it is when I freeze one of the two rib eye steaks I got on sale at QFC and eat it two months later whereby it tastes just about as delicious as the first one

The other problem is dealing with the senescence factors of the genes and the existing structural degredation of the neural networks pre-preservation. To me, that's the real practical, even ethical consideration of cryogenics/preservation. Grandma's about to get the plug pulled and you want to cryo-preserve her. Fine, say you can and keep everything intact, "as is." But what's going to happen later on when you thaw her out 100 years later? You're just going to have grandma back in ICU ready to die again. So the issue isn't really about preservation per se. It's a much, much more complicated issue.
Ryan_m_b
#3
Aug14-14, 08:42 AM
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Whole organ cryopreservation is a technology that is under research, mainly for the boon it would give to transplants and regenerative medicine. But it's a fiendishly complicated thing to do for the reasons you've mentioned. Brain preservation is another matter entirely because of the question "then what"? So you have a frozen brain, why is that useful? Are you going to keep it in a vat for decades, hoping that some radical future technology will allow a new body to be grown for it? Who is going to pay for that and how likely is that technology to come about in any reasonable time frame? Aside from niche interest few people actually care about preserving their brains to await some utopic future. Therefore research is focussed on practical uses that can be achieved in the near future.

On a related note there have been surgeries performed with the brain cooled to a much lower temperature for preservation: http://www.bbc.com/news/health-11389464

zoobyshoe
#4
Aug17-14, 12:10 AM
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How to approach the problem of brain preservation?

In the same vein as DiracPool's remarks...

I read this book a couple years ago:

http://www.amazon.com/Case-Frozen-Ad.../dp/1614993319

and in it the author asserts that everyone's substantia nigra deteriorates with age. Parkinson's is a pathological acceleration of that normal aging process. If our bodies lasted longer and we lived to be, say, 140, we'd all end up with Parkinson's. A 'body transplant' would only doom the recipient to that fate.
lsparrish
#5
Aug17-14, 04:40 PM
P: 2
Quote Quote by Ryan_m_b View Post
Brain preservation is another matter entirely because of the question "then what"? So you have a frozen brain, why is that useful? Are you going to keep it in a vat for decades, hoping that some radical future technology will allow a new body to be grown for it?
Yes, of course. Perhaps over a century, even. The physics allow it.

Who is going to pay for that and how likely is that technology to come about in any reasonable time frame?
It isn't all that expensive to store tissue cryogenically for a long period of time. A few thousand dollars (usually paid with life insurance) generates the necessary compound interest under conservative assumptions. (People in cryonics actually do this, despite the fact that they know the tissue is no longer viable, just morphologically preserved.)

On the second question, it cannot be answered without speculation. Since this is not a forum for speculation, we can't really take this line of reasoning any further in this venue (other than to note that the reasonable amount of time for this purpose can be fairly long).

Aside from niche interest few people actually care about preserving their brains to await some utopic future. Therefore research is focussed on practical uses that can be achieved in the near future.
It does seem to be a marginalized interest, currently. However, the niche might be more influential than one would think, at least on the side of things interesting to larger scale applications in tissue engineering. For example, Brian Wowk and Greg Fahy (who you cited) are prominent cryobiologists as well as cryonicists.

Their focus has been on the kidney, and they have written extensively about non-cryonics uses for the technology; however, there are clear pragmatic reasons for this. (Those uses are nearer term, less controversial/politicized, and clearly interesting for health applications, including life extension.) Their company is currently competing for the brain preservation prize, nonetheless.

On the other hand, cryofixation for EM is usually rapid-cooling vitrification (Luyet's approach), not high-osmolality (Fahy's approach), and many scientists seem unaware of the existence of the latter. (One example that might be familiar is Michio Kaku's strikingly uninformed critique of "cryogenics", which does not even mention vitrification.) This may be because the idea has only been known to be useful for a short period of time (e.g. in reproductive medicine), so older scientists did not have exposure to the concept during their early careers.

On a related note there have been surgeries performed with the brain cooled to a much lower temperature for preservation: http://www.bbc.com/news/health-11389464
Although the temperatures are lower than is typical in hypothermic medicine, this is still a significantly different matter from the prospect of long-term storage. It is interesting though, and any mechanism for preserving the brain would probably involve a hypothermic stage.

Quote Quote by zoobyshoe
If our bodies lasted longer and we lived to be, say, 140, we'd all end up with Parkinson's. A 'body transplant' would only doom the recipient to that fate.
That is an interesting point, however a body transplant should still be useful in conjunction with the development of anti-Parkinson's treatments (and treatments for any other manifestations of neural senescence). The fact that fetal stem cells aided the recovery of some of the victims in the book makes me think we have already made significant progress.

Quote Quote by DiracPool
So the issue isn't really about preservation per se. It's a much, much more complicated issue.
It is true that there is a lot of complexity associated with the issue, including the inherently speculative aspect of whether a new body/functional analogue can be made, as well as organizational stability and so forth. But I think preservation is the most interesting and least speculative aspect from the current scientific perspective. How can we improve preservation, in light of the obstacles I mentioned?


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