A common complaint against cryonics is that existing cryopreservation technologies may not be good enough to preserve the ultrastructure of the human brain. Advocates of cryonics often object that such views do not reflect actual inspection of the evidence of cryopreserved brains but instead reflect misconceptions about “freezing” and ice formation rupturing cells. But the more fundamental misconception rests on the view that for cryonics to work flawless preservation of the brain is absolutely essential.

This view is not only mistaken but holds cryonics to higher standards than those applied in conventional medicine. In medicine it is routine for patients to present themselves with conditions in which an organ or tissue has been changed from its normal condition (or appearance) as a result of disease or trauma. Restoring normal structure or function is the essence of most medical treatments.

One might object that in the case of cryonics we are concerned with the brain, which distinguishes itself from other organs that encodes highly individual information. If a portion of the brain is erased we cannot consult another brain or medical textbook to infer its original state. We can admit that this is a valid observation but it is not necessarily a fatal argument against cryonics, provided the damage has not reached the point of complete destruction or indecipherability.

There is a difference between damage and obliteration. If we look at electron micrographs of brain tissue produced at various points in time after circulatory arrest (“death”) we will observe progressive alterations of synapses, cell membranes, organelles etc. We describe such changes with a mental (or actual) map of how they normally look like in mind. At this level the fact that the brain is a highly individual organ is no longer relevant because we know the universal biochemical language in which this identity is written. At this point the real question becomes at which point is it not even possible to infer the original condition of the brain. As far as we understand this today, this may be a question of many hours, if not days.

This robustness of identity-critical information in the brain may seem to contradict the routine observation in emergency medicine that there is a much narrower time limit for successful resuscitation from cardiac arrest. The crucial difference here is that we are no longer talking about the ability to infer identity-critical information but restore physiological function. But function is a lot more vulnerable to metabolic and biochemical changes than the wiring of the brain. In fact, if function were a necessary requirement to infer information a lot of existing forensic and archeological science would be impossible.

In approaching cryonics it is important to recognize the distinction between preserving and inferring. In this way we can better assess the prospects for resuscitating patients who were cryopreserved under nonideal conditions and/or with older technologies.

Originally published as a column in Cryonics magazine 2012-5.