20. June 2012 · Comments Off · Categories: Cryonics, Death, Neuroscience

It is generally not the task of scientists to consider the legal, financial, and logistical limitations when searching for biomedical breakthroughs but there are good examples where considering the real-world applications of a technology can be instructive. Research aimed at preservation of brains (or the “connectome”) is such an example. Even if chemopreservation can be demonstrated to preserve the intricate wiring of the brain, it can be safely assumed that there will not be a massive change in demand for brain preservation technologies (especially if the technology is too strongly tied to mind uploading). As a consequence, providers of chemopreservation will most likely operate in the same environment as providers of cryonics. That means that, as a general rule, there will be a delay between pronouncement of legal death and the start of procedures.

There is now more than 40 years of mainstream biomedical research demonstrating that even short interruptions of circulation (under normothermic conditions) can produce perfusion impairment in the brain. As has been demonstrated by cryonics researcher Mike Darwin and my own lab, Advanced Neural Biosciences, this “no-reflow” can produce poor distribution of cryoprotectants (including vitrification agents) and associated freezing. One serious concern that cryonics researchers have about chemopreservation-in-the-real-world is that poorly chemically fixed brains will be prone to autolysis during long-term storage. This limitation of chemopreservation applies to both “conventional” biological resuscitation scenarios as to whole brain emulation. One can only recover (or “upload”) what is preserved – or can be inferred. And as far as we understand things today, the advantage of temperature as a long-term preservation method is that it does not depend on a healthy, non-ischemic circulatory system. Cryopreservation of an ischemic brain can produce ice formation, but as soon as it is placed in liquid nitrogen, cold will “fix” whatever there is without further degradation. The same thing cannot be said about chemopreservation under poor conditions.

There is an understandable tendency to compare brain preservation protocols under ideal conditions and favor the method that produces the best preservation. But support for either technology cannot be solely based on results produces under controlled lab conditions. Personal survival technologies should be evaluated under conditions that are most likely to be encountered by organizations that will offer them. Demonstrating that chemical fixation (and plastination) can preserve the connectome is a laudable goal but the case for chemopreservation as a clinical experimental preservation method requires a persuasive response to the objection that delays in fixation can frustrate the aims of chemopreservation in the most fundamental manner.

One interesting aspect of the cryonics vs chemopreservation debate, though, is that it appears that some people simply feel more comfortable with one of the approaches. People who have shown the slightest interest in human cryopreservation can get really excited about the idea of chemical brain preservation. This indicates that if both approaches would be pursued actively, the growth of chemopreservation would not necessarily be at the expense of cryonics but there would be a growth in the total number of people making bio-preservation arrangements aimed at personal survival. But as Mike Darwin has recently pointed out, chemopreservation is not at the stage where it can be responsibly offered. The growth of this field requires a committed group of individuals who will research, develop, and implement this program. Chemopreservation does not need to be perfected before being offered (neither was cryonics) but so far most advocacy has been mostly at the conceptual level.

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