What data support brain cryopreservation?
Prior to the 1990s, estimations of freezing damage in the brain relied mostly on indirect information. This information included numerous studies showing recovery of neuronal cells and synapse metabolism following freezing to cryogenic temperatures with modest cryoprotection. Even whole brains were known to briefly recover normal electrical activity after freezing to -20ºC for five days with glycerol cryoprotection. In 1995, a study showing excellent preservation of brain structure following perfusion with 7.4 Molar (68% w/v) glycerol and freezing to -90ºC was published on the Internet and in a cryonics periodical. The study essentially duplicated in large dogs the best cryonics protocols used on humans at that time. Although cooling was only to -90ºC, no further ice formation would be expected during cooling to liquid nitrogen temperature (-196ºC) because the remaining unfrozen solution is too concentrated to freeze. 70% w/v glycerol is almost unfreezable. This means that after formin
