For some people, the idea of decapitation seems like the ultimate horror—a head without a body, a body without a head! It’s very strange, then, to think that having people cut off your head—at the right time, in the right way—might just save your life.

In cryonics—the experimental science of storing "dead" persons at very low temperatures in a way that may facilitate their potential revival at in the future—this is called "neuropreservation" or "neurosuspension." In this procedure, which cryonics organization Alcor first undertook in 1976, cryonicists store only the head of a neuropatient instead of preserving the whole body.

I am a "cryonicist," meaning I have signed up for cryonic preservation (in my case, this "neuro," head-only type). The science, though partly speculative, really matters to me. My new book Frozen to Life: A Personal Mortality Experiment explores the radical science and philosophy of brain, mind, and "self" involved. It also dives into my personal journey to this heady, but not hasty, decision.

SUSPENDED HEAD, SUSPENDED SELF?

Most philosophers (and scientists) think that the "self" (or whatever you like to call what makes you you) is generated as an emergent property of the physical processes of your brain. So, your brain is the crucial physical part of you that technicians will need to retain and preserve after your death if your self is ever again going to enjoy the warm glow of sunshine. And it’s easier to retain your brain within the protective casing of your skull than to remove it, risking damage.

Of course, many cryonicists choose whole-body preservation. For non-cryonicists, that choice evokes less revulsion than head-only; strong social taboos against cadaver dismemberment persist. To me, however, neuro makes good sense. Being much smaller than a whole body, a head is easier and cheaper (for example, it requires only one-tenth as much liquid nitrogen) to preserve and store efficiently. Intuitively, revival from whole-body is more plausible; in actuality, provisioning and connecting a new body is far from being the biggest technical challenge cryonic revival will involve.

HOW THE PROCESS WORKS

To maximize your chances of successful preservation, it’s best to die near to a cryonics facility. If you signed up with Alcor, Scottsdale, AZ., is a good place to breathe your last breath. After a doctor pronounces you brain dead, Alcor’s standby team takes over. First, they place you in an ice bath to begin the cooling process and to slow cell degradation. Then they attach a "thumper"—a mechanical chest compression device—to your body to keep blood circulating, oxygenating your brain. Anticoagulants such as heparin, introduced intravenously, help stop blood clotting. At that point, the team considers you "stabilized" and ready for transport back to Alcor’s facility.

There, surgeons cool the body further to around 0°C, before performing the neuroseparation procedure (cutting through the neck to remove the head). They wash out the blood and replace it with a "cryoprotectant" solution containing antifreeze-type chemicals. After surgeons have attached a monitoring device and placed the cephalon (head) in a "neurocan," it is ready for a multistage cooling process, which eventually takes it down to the final storage temperature of -196°C.

HEAD OF GLASS

If you want to keep a brain’s structure intact and potentially recoverable, freezing it won’t work well. Instead, you need to "vitrify" it. Blood plasma is watery, and ice crystals rupture cells. The heavy concentration of cryoprotectant and careful cooling promote a smooth, glass-like vitrified tissue state.

But what use is a vitrified head? It’s true that we can’t bring the dead back to life, and also that no living human head has ever been re-attached to a donor body. However, we aren’t discussing doing those things using today’s technologies; we’re talking about trying to put a human brain "on pause" so that, when the necessary technologies and procedures arrive, future medics can reboot it.

To do that, they would likely use advanced forms of nanomedicine. Repairing fine-scale damage in the wiring of a brain—what neuroscientists call its connectome—is currently impossible, but who knows what the future holds? A suitably repaired and rebooted brain might find itself getting to grips with a newly cloned body (or a cybernetic one, or a convincingly virtual one).

SPECTRUMS, NOT SPECTRES

A recent New York Times article discussed the case of Kim Suozzi, who died in 2013 of brain cancer at the age of just 23, and was neuropreserved at Alcor. While she was fundraising to be cryopreserved, her father had disapproved of her decision, saying to her, "We don’t get to live forever, Kim." But cryonicists don’t generally expect to "live forever." Cryonicists don’t speak of death with the finality that most people do. We see life and death on a spectrum, with true death being the complete dissolution of the information-carrying capacity of the brain. Cryptographer Ralph Merkle coined the term "information-theoretic death" to describe the absolute dead-end of the life/death spectrum.

The debate about cryonics is only just getting started. We’re so used to our customary ways of dealing with the dead, that the idea they might not be irretrievably gone may come as a bit of a shock. Nevertheless, perhaps it’s about time we at least took a more nuanced view of death. After all, people used to think that death occurred the moment the heart stopped beating, and that turned out to be woefully incorrect.

And, of course, the soul is something of a stumbling block to changing our approach to death. If you think that some essential, non-material part of you survives your death anyway, why would you go to all the trouble of having your head frozen in the first place?