In this 2020 Ask My Anything Video, Elon Musk is asked about cryonics. In a nutshell, Elon answers that if the brain is frozen quickly after death, then it would be possible to extract enough information to revive the person. While the brain is a stunning organ, it is still a material entity and its original state could be inferred from the damaged state, according to Musk.

He also appears to refer to rat studies in which learned behavior (such as navigating a maze) can be inferred from the brain after freezing. It is not completely clear which studies Musk is referring to here.

Pichugin and Fahy have demonstrated recovery of potassium/sodium ratio’s after vitrification of hippocampal rat brain slices. This work has been further extended at 21st Century Medicine, who, in 2007, reported maintenance of long-term potentiation (LTP) in vitrified rabbit brain slices. The most impressive demonstration of preservation of whole-brain viability was reportedly achieved by Isamu Suda in 1996 and 1974 who recovered organized electrical activity (i.e., EEG) in cat brains after freezing with low glycerol concentrations and prolonged refrigerator storage. To this date, this research has not been duplicated but whole-brain recovery research is currently conducted by research companies such as Advanced Neural Biosciences and 21st Century Medicine.

Although recovery of whole-brain viability after cryopreservation (vitrification) would further bolster the science and practice of cryonics, this achievement is not necessary for cryonics to succeed. If the fine structure of the brain is adequately preserved, or at least in a state from which the original state can be inferred through deep learning (i.e., reconstructive connectomics), revival of the original individual should be possible in principle.