Two-year-old Matheryn Naovaratpong of Thailand died in January 2015 from a rare form of brain cancer. But her parents live in hope of seeing her again some day. The couple has given their daughter’s brain to a facility in Arizona to be preserved until medical technology advances to a stage when she can be revived. Kim Souzzi’s brain is also in deep freeze at the Arizona lab. Souzzi, an American, died in January 2013 at the age of 23.

The Arizona lab belongs to a company called Alcor that has received more than 100 bodies to preserve by freezing them. Alcor CEO Max Moore describes cryonics as “the next level in critical care”. The philosophy behind the operation is that death today has been determined by how far medical science has progressed, to the point where doctors have been told to let go. Preserving a body might give medical science a chance to catch up.

A person can choose to donate his or her whole body or just the brain to Alcor, which promises to try to revive them, if ever medical technology to do so becomes available. The bodies and brains are preserved in large cans of liquid nitrogen.

Tissue engineering is already sophisticated enough to allow almost any body part to be regenerated from living cells or manufacturing using biosynthetics. At the same time scientists around the world are exploring the functioning of a brain with great rigour. They are probing the borders between the physical brain and the intangible mind, mapping synaptic connections between neurons that might determine human qualities of memory and identity.

Cryonics deserves open-minded discussion, argues a new editorial in the MIT Technology Review. The authors say that although no one understands the cell physiology in entirety, almost every kind of cell has been successfully cryopreserved. “Similarly, while the neurological basis for memory, behaviour, and other features of a person’s identity may be staggeringly complex, understanding this complexity is a problem largely independent of being able to preserve it,” they say.

Matheryn’s parents believe, just like Souzzi did, that it might just be possible that scientists will have a breakthrough and the person who died will return, as though they have woken up from a coma.