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There is a helpful web page on the probability that cryonics will work.

There are also some useful facts at the Alcor Scientists' Cryonics FAQ.

The neuroscientist might wish to pay attention to the answer to "Q: Can a brain stop working without losing information?" The referenced article by Mayford, Siegelbaum, and Kandel should be particularly helpful.

To quote a discussion of long term memory and the specific synaptic changes that take place from Molecular Repair of the Brain:

What, exactly, might these changes be? Very strong statements are possible in simple "model systems". Bailey and Chen, for example, identified several specific changes in synaptic structure that encoded learned memories from sea slugs (Aplysia californica) by direct examination of the changed synapse with an electron microscope[36].

"Using horseradish peroxidase (HRP) to label the presynaptic terminals (varicosities) of sensory neurons and serial reconstruction to analyze synaptic contacts, we compared the fine structure of identified sensory neuron synapses in control and behaviorally modified animals. Our results indicate that learning can modulate long-term synaptic effectiveness by altering the number, size, and vesical complement of synaptic active zones."

  1. "Morphological basis of long-term habituation and sensitization in Aplysia" by Craig H. Bailey and Mary Chen, Science 220, April 1, 1983, pages 91-93

A few comments:

1) Sign up for cryonics now. Do not delay because you think "Plastination might be better someday in the future".

  • No one is offering plastination now, and you can die now.
  • It's not clear when, if ever, anyone is going to offer plastination.
  • It's not clear that plastination, if actually offered, will actually be better than cryonics.

2) With chemical preservation, good vascular perfusion is critical. Brain tissue which is not perfused is lost.

3) With cryopreservation, good vascular perfusion results in excellent preservation by vitrification. Brain tissue which is not perfused is still preserved.

4) Most of the costs for neuropreservation are from the up-front logistical and surgical costs. If you want minimal ischemic time and good vascular perfusion for chemical preservation you're still going to have to pay most if not all of those costs.

You'll need to read Molecular Repair of the Brain. Note that it discusses a variety of repair methods, including methods which carry out repairs at sufficiently low temperatures (between 4K and 77K) that there is no risk that "molecular drift" would undo previous work. By making incredibly conservative assumptions about the speed of operations, it is possible to stretch out the time required to repair a system the size of the human brain to three years, but really this time was chosen for psychological reasons. Repairing a person "too quickly" seems to annoy people.

You might also want to read Convergent Assembly. As this is a technical paper which makes no mention of controversial topics, it provides more realistic estimates of manufacturing times. Total manufacturing time for rigid objects such as a human brain at (say) 20K are likely to be 100 to 1000 seconds. This does not include the time required to analyze your cryopreserved brain and determine the healthy state, which is likely to be significantly longer. Note that some alterations to the healthy state (the blueprints) will be required prior to manufacture, including various modifications to facilitate manufacture, the inclusion of heating elements for rewarming, and various control systems to monitor and modulate the rewarming and metabolic start-up processes as well as the resumption of consciousness.

After you've had time to digest the paper, I'd be interested in your comments. As Ciphergoth has said, there are no (repeat no) credible arguments against the feasibility of cryonics in the extant literature. If you have any, it would be most interesting.

As a neuroscientist, you might also be amused by Large Scale Analysis of Neural Structures.

For recent work on vitrification, I refer you to Greg Fahy at 21st Century Medicine.

The Alcor FAQ has a question and answer relevant to this discussion:

Q: Why haven't more people signed up for cryonics?

A: People don't sign up for cryonics because: it's not traditional, they're skeptical of anything they haven't seen work, it costs money, they're afraid of what their friends might think, they live in denial of their own death, they don't want to think about the subject, they procrastinate, they don't like life well enough to want more of it, or they are afraid of a future in which they may be alienated from friends and family and a familiar social environment.

Typical Alcor members (if any Alcor member could be called "typical") tend to be highly educated independent minded people who enjoy life and think cryonics has a reasonable chance of working. They pay for it with life insurance and think the future is likely to work out pretty well. They often have friends or relatives who are Alcor members. They expect Alcor to revive them using nanomedicine and expect to continue their lives with as much passion and joy as today — only with much more amazing technology.

You might want to read Cryonics, cryptography, and maximum likelihood estimation.

Short summary: if cryptanalytic methods can recover the wiring of World War II rotor machines knowing only some input-output pairs and with only limited information about the actual wiring, then similar algorithms should be able to recover the neuronal "wiring" between different cortical areas when we already have a wealth of information about that wiring plus a good knowledge of acceptable input-output pairs.

How many bytes in human memory? is a very brief article providing estimates of just that. Evidence from human learning experiments suggests that, after using a very good data compression algorithm, human long term declarative memory holds only a few hundred megabytes.

How much of that information is common knowledge, such as knowledge of the English language, memories from media such as books or television, or knowledge of local buildings and streets, is unclear.

Additional information specific to an individual could be gained from email, internet posts, and other personal electronic information and written records, such as diaries; as well as individual genomes, which will soon be ubiquitously available.

The modest information content of human declarative memory might be relevant to some of the discussions on this thread.

General advice: if you can afford it, sign up with Alcor. If you can't, sign up with CI.

If you want more information, I'd recommend the Alcor FAQs.

I should provide some context for my comments on Alcor's previous track record on creating endowments: we had just received a $7M bequest, had placed $3.5M into the Patient Care Trust Fund, and the Board had decided to put the other $3.5M into an Endowment and withdraw only 2% per annum, or about $70,000 per year, for Alcor's operational needs. Some members were feeling quite euphoric and were proposing that we spend some significant amount of the principal on various worthy projects, including reduced dues for said members and increased spending on certain pet projects. It seemed advisable to inject a note of sobriety into the discussion and to somewhat deflate the expanding expectations. While helpful, this bequest did not free us from the constraints of fiscal responsibility, and explaining why the Board was being so parsimonious with this windfall seemed appropriate at the time.

Given this context, I wouldn't interpret these comments as "disturbing".

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