Cryonics (from Greek κρύος 'kryos-' meaning 'icy cold') is the low-temperature preservation of animals and humans who cannot be sustained by contemporary medicine, with the hope that healing and resuscitation may be possible in the future.
Cryopreservation of people or large animals is not reversible with current technology. The stated rationale for cryonics is that people who are considered dead by current legal or medical definitions may not necessarily be dead according to the more stringent information-theoretic definition of death. It is proposed that cryopreserved people might someday be recovered by using highly advanced technology.
Some scientific literature supports the feasibility of cryonics. An open letter supporting the idea of cryonics has been signed by 63 scientists, including Aubrey de Grey and Marvin Minsky. However, many other scientists regard cryonics with skepticism. As of 2013, approximately 270 people have undergone cryopreservation procedures since cryonics was first proposed in 1962. In the United States, cryonics can only be legally performed on humans after they have been pronounced legally dead, as otherwise it would be considered murder or assisted suicide.
Cryonics procedures ideally begin within minutes of cardiac arrest, and use cryoprotectants to prevent ice formation during cryopreservation. However, the idea of cryonics also includes preservation of people long after legal death because of the possibility that brain structures that encode memory and personality may still persist and be inferable in the future. Whether sufficient brain information still exists for cryonics to successfully preserve may be intrinsically unprovable by present knowledge. Therefore, most proponents of cryonics see it as an intervention with prospects for success that vary widely depending on circumstances.
- 1 Premises
- 2 Obstacles to success
- 3 Neuropreservation
- 4 Legal issues
- 5 Standby services and transportation
- 6 Ethical considerations
- 7 History
- 8 In popular culture
- 9 See also
- 10 References
- 11 External links
A central premise of cryonics is that long-term memory, personality, and identity are stored in durable cell structures and patterns within the brain that do not require continuous brain activity to survive. This premise is generally accepted in medicine; it is known that under certain conditions the brain can stop functioning and still later recover with retention of long-term memory. Additional scientific premises of cryonics are that (1) brain structures encoding personality and long-term memory persist for some time after legal death, (2) these structures are preserved by cryopreservation, and (3) future technologies that could restore encoded memories to functional expression in a healed person are theoretically possible. At present only cells, tissues, and some small organs can be reversibly cryopreserved.
Cryonics advocates say it is possible to preserve the fine cell structures of the brain in which memory and identity reside with present technology. They say that demonstrably reversible cryopreservation is not necessary to achieve the present-day goal of cryonics, which is preservation of brain information that encodes memory and personal identity. They say current cryonics procedures can preserve the anatomical basis of mind, and that this should be sufficient to prevent information-theoretic death until future repairs might be possible.
A moral premise of cryonics is that all terminally ill patients should have the right, if they so choose, to be cryopreserved. Some cryonicists believe as a matter of principle that anyone who would ordinarily be regarded as dead should instead be made a "permanent patient" subject to whatever future advances might bring.
Obstacles to success
Long-term cryopreservation can be achieved by cooling to near 77.15 Kelvin (approximately -196.01°C), the boiling point of liquid nitrogen. It is a common mistaken belief that cells will lyse (burst) due to the formation of ice crystals within the cell, since this only occurs if the freezing rate exceeds the osmotic loss of water to the extracellular space. However, damage from freezing can still be serious; ice may still form between cells, causing mechanical and chemical damage. Cryonics organizations use cryoprotectants to reduce this damage. Cryoprotectant solutions are circulated through blood vessels to remove and replace water inside cells with chemicals that prevent freezing. This can reduce damage greatly, but freezing of the entire body still causes injuries that are not reversible with present technology. The difficulties of recovering complex organisms from a frozen state have been long known. Attempts to recover large frozen mammals by simply rewarming were abandoned by 1957.
When used at high concentrations, cryoprotectants stop ice formation completely. Cooling and solidification without crystal formation is called vitrification. The first cryoprotectant solutions able to vitrify at very slow cooling rates while still being compatible with tissue survival were developed in the late 1990s by cryobiologists Gregory Fahy and Brian Wowk for the purpose of banking transplantable organs. These solutions were adopted for use in cryonics by the Alcor Life Extension Foundation, for which they are believed to permit vitrification of some parts of the human body, especially the brain. This has allowed animal brains to be vitrified, warmed back up, and examined for ice damage using light and electron microscopy. No ice crystal damage was found. The Cryonics Institute also uses a vitrification solution developed by their staff cryobiologist, Yuri Pichugin, applying it principally to the brain.
Vitrification in cryonics is different from vitrification in mainstream cryobiology because vitrification in cryonics is not reversible with current technology. It is only structural vitrification. When successful, it can prevent freezing injury in some body parts, but at the price of toxicity caused by cryoprotectant chemicals. The nature of this toxicity is still poorly understood. Cryonicists assume that toxicity is more subtle and repairable than obvious structural damage that would otherwise be caused by freezing. If, for example, toxicity is due to denatured proteins, those proteins could be repaired or replaced.
Ischemia means inadequate or absent blood circulation that deprives tissue of oxygen and nutrients. At least several minutes of ischemia is a typical part of cryonics because of the common legal requirement that cryonics procedures do not begin until after blood circulation stops. The heart must stop beating so that legal death can be declared. When there is advance notice of impending legal death, it is sometimes possible to deploy a team of technicians to perform a “standby procedure”. The team artificially restores blood circulation and breathing using techniques similar to cardiopulmonary resuscitation as soon as possible after the heart stops. The aim is to keep tissues alive after legal death by analogy to conventional medical procedures in which viable organs and tissues are obtained for transplant from legally deceased donors. Legal death does not mean that all the cells of the body have died.
Often in cryonics the brain is without oxygen for many minutes at warm temperatures, or even hours if the heart stops unexpectedly. This causes ischemic injury to the brain and other tissues that makes resuscitation impossible by present medical technology. Cryonicists justify preservation under such conditions by noting recent advances that allow brain resuscitation after longer periods of ischemia than the traditional 4-to-6-minute limit, and persistence of brain structure and even some brain cell function after long periods of clinical death. They argue that definitions of death change as technology advances, and the early stages of what is called “death” today is actually a form of ischemic injury that will be reversible in the future. They claim that personal survival during long periods of clinical death is determined by information-theoretic criteria.
Those who believe that revival may someday be possible generally look toward advanced bioengineering, molecular nanotechnology, or nanomedicine as key technologies. Revival would require repairing damage from lack of oxygen, cryoprotectant toxicity, thermal stress (fracturing), freezing in tissues that do not successfully vitrify, and reversing the effects that caused the patient's death. In many cases extensive tissue regeneration would be necessary. Hypothetical revival scenarios generally envision repairs being performed by vast numbers of microscopic organisms or devices. These devices would restore healthy cell structure and chemistry at the molecular level, ideally before warming. Mind uploading is another possibility that is frequently discussed. Transferring the information content of a cryopreserved brain into an artificial brain may be no more or less feasible than re-growing a biological body, especially to a society with technology capable of reviving cryopreserved brain tissue.
It has sometimes been written that cryonics revival will be a last in, first out process. People cryopreserved in the future, with better technology, may require less advanced technology to be revived because they will have been cryopreserved with better technology that caused less damage to tissue. In this view, preservation methods would get progressively better until eventually they are demonstrably reversible, after which medicine would begin to reach back and revive people cryopreserved by more primitive methods. Revival of people cryopreserved by early cryonics technology may require centuries, if it is possible at all. The "last in, first out" view of cryonics has been criticized because the quality of cryopreservation depends on many factors other than the era in which cryopreservation takes place.
It has been claimed that if technologies for general molecular analysis and repair are ever developed, then theoretically any damaged body could be “revived”. Survival would then depend on whether preserved brain information was sufficient to permit restoration of all or part of the personal identity of the original person, with amnesia being the final dividing line between success and failure.
Neuropreservation is cryopreservation of the brain, often within the head, with surgical removal and disposal (usually cremation) of the rest of the body. Neuropreservation, sometimes called “neuro,” is one of two distinct preservation options in cryonics, the other being "whole body" preservation.
Neuropreservation is motivated by the brain's role as the primary repository of memory and personal identity. (For instance, spinal cord injury victims, organ transplant patients, and amputees retain their personal identity.) It is also motivated by the belief that reversing any type of cryonic preservation is so difficult and complex that any future technology capable of it must by its nature be capable of generalized tissue regeneration, including growth of a new body around a repaired brain. Some suggested revival scenarios for whole body patients even involve discarding the original body and regenerating a new body because tissues are so badly damaged by the preservation process. These considerations, along with lower costs, easier transportation in emergencies, and the specific focus on brain preservation quality, have motivated many cryonicists to choose neuropreservation.
The advantages and disadvantages of neuropreservation are often debated among cryonics advocates. Critics of neuropreservation note that the body is a record of much life experience. While few cryonicists doubt that a revived neuro patient would be the same person, there are wider questions about how a regenerated body might feel different from the original. Partly for these reasons (as well as for better public relations), the Cryonics Institute preserves only whole bodies. Some proponents of neuropreservation agree with these concerns, but still feel that lower costs and better brain preservation justify concentrating preservation efforts on the brain. About two-thirds of the patients stored at Alcor are neuropreservation patients. Although the American Cryonics Society no longer offers the neuropreservation option, about half of their patients are "neuros".
Legally, cryonics patients are treated as deceased persons. A long established legal tradition, the concept of "lost persons," permits a person who has been declared legally dead to later be declared legally alive. Cryonics providers tend to be treated as medical research institutes. In France, cryonics is not considered a legal mode of body disposal; only burial, cremation, and formal donation to science are allowed. However, bodies may legally be shipped to other, less restrictive countries for cryonic freezing.
Standby services and transportation
Standby and transportation is a critical phase in a cryopreservation process. Cryonics patients need a professional response team to stand ready for suspended animation, when the patients are declared legally dead. Standby services include stabilization, cooling, and other procedures to ensure that the damage to the patient during transportation is minimal. Some cryonics services providers may provide standby as well as transportation services to their client.
Cryonics is based on a view of dying as a process that can be stopped in the minutes, and perhaps hours, following legal death. If death is not an event that happens suddenly when the heart stops (and "legal death" is often pronounced) this raises philosophical questions about what exactly death is. In 2005 an ethics debate in the medical journal, Critical Care, noted “…few if any patients pronounced dead by today’s physicians are in fact truly dead by any scientifically rigorous criteria.” Cryonics proponent Thomas Donaldson has argued that “death” based on cardiac arrest or resuscitation failure is a purely social construction used to justify terminating care of dying patients. In this view, legal death and its aftermath are a form of euthanasia in which sick people are abandoned. Philosopher Max More suggested a distinction between death associated with circumstances and intention versus death that is absolutely irreversible. Absolutely irreversible death has also been called information-theoretic death, which implies destruction of the brain to such an extent that the original information content can no longer be recovered. Bioethicist James Hughes has written that increasing rights will accrue to cryonics patients as prospects for revival become clearer, noting that recovery of legally dead persons has precedent in the discovery of missing persons.
Ethical and theological opinions of cryonics tend to pivot on the issue of whether cryonics is regarded as interment or medicine. If cryonics is interment, then religious beliefs about death and afterlife may come into consideration. Resuscitation may be deemed impossible by those with religious beliefs because the soul is gone, and according to most religions only a deity can resurrect the dead. Cryonics advocates say theological dismissal of cryonics because it is interment is a circular argument because calling cryonics "interment" presumes a priori that cryonics cannot work. They believe future technical advances will validate their view that cryonics patients are recoverable, and therefore never really dead. If cryonics is regarded as medicine, with legal death as a mere enabling mechanism, then cryonics is a long-term coma with uncertain prognosis.
Alcor has published a vigorous Christian defense of cryonics, including excerpts of a sermon by Lutheran Reverend Kay Glaesner. Noted Christian commentator John Warwick Montgomery has defended cryonics. In 1969, a Roman Catholic priest consecrated the cryonics capsule of Ann DeBlasio, one of the first cryonics patients. Many followers of Nikolai Fyodorovich Fyodorov see cryonics as an important step in the Common Cause project.
At the request of the American Cryonics Society, in 1995, Philosopher Charles Tandy, Ph.D.  authored a paper entitled “Cryonic-Hibernation in Light of the Bioethical Principles of Beauchamp and Childress.” Tandy considered the four bioethical factors or principles articulated by philosophers Beauchamp and Childress as they apply to cryonics. These four principles are 1) respect for autonomy; 2) nonmaleficence; 3) beneficence; and 4) justice. Tandy concluded that in respect to all four principles “biomedical professionals have a strong (not weak) and actual (not prima facie, but binding) obligation to help insure cryonic-hibernation of the cryonics patient.”
In 1922 Alexander Yaroslavsky, member of Russian immortalists-biocosmists movement, wrote "Anabiosys Poem". However, the modern era of cryonics began in 1962 when Michigan college physics teacher Robert Ettinger proposed in a privately published book, The Prospect of Immortality, that freezing people may be a way to reach future medical technology. (The book was republished in 2005 and remains in print.) Even though freezing a person is apparently fatal, Ettinger argued that what appears to be fatal today may be reversible in the future. He applied the same argument to the process of dying itself, saying that the early stages of clinical death may be reversible in the future. Combining these two ideas, he suggested that freezing recently deceased people may be a way to save lives. In 1955 James Lovelock was able to reanimate rats frozen at 0 Celsius using microwave diathermy.
Slightly before Ettinger’s book was complete, Evan Cooper (writing as Nathan Duhring) privately published a book called Immortality: Physically, Scientifically, Now that independently suggested the same idea. Cooper founded the Life Extension Society (LES) in 1964 to promote freezing people. Ettinger came to be credited as the originator of cryonics, perhaps because his book was republished by Doubleday in 1964 on recommendation of Isaac Asimov and Fred Pohl, and received more publicity. Ettinger also stayed with the movement longer. Nevertheless, Alcor's in-house historian, R. Michael Perry, has written “Evan Cooper deserves the principal credit for forming an organized cryonics movement.” The first LES newsletter credits Lawrence Neil Jensen, an art professor at Castleton State College, as "one of the original formulators of the 'freeze and wait' theory." Jensen helped raise awareness of the concept through such means as a letter to President Kennedy, a presentation at Green Mountain College, and an appearance with Ettinger on the Mike Douglas Show in 1965.
Cooper’s Life Extension Society became the seed tree for cryonics societies throughout the United States where local cryonics advocates would get together as a result of contact through the LES mailing list. The actual word “cryonics” was invented by Karl Werner, then a student in the studio of William Katavolos at Pratt Institute in Brooklyn, NY, in 1965 in conjunction with the founding of the Cryonics Society of New York (CSNY) by Curtis Henderson and Saul Kent that same year. This was followed by the founding of the Cryonics Society of Michigan (CSM) and Cryonics Society of California (CSC) in 1966, and Bay Area Cryonics Society (BACS) in 1969 (renamed the American Cryonics Society, or ACS, in 1985). Neither CSNY nor CSC are currently in operation. CSM eventually became the Immortalist Society, a non-profit affiliate of the Cryonics Institute (CI), a cryonics service organization founded by Ettinger in 1976. Alcor now has more current cryonics patients than any other organization, 110 as of December 2011.
Although there was at least one earlier aborted case, it is generally accepted that the first person frozen with intent of future resuscitation was James Bedford, a 73-year-old psychology professor frozen under crude conditions by CSC on January 12, 1967. The case made the cover of a limited print run of Life magazine before the presses were stopped to report the death of three astronauts in the Apollo 1 fire instead. Bedford is still frozen today at Alcor.
Cryonics suffered a major setback in 1979 when it was discovered that nine bodies stored by the head of the CSC, Robert Nelson, in a cemetery in Chatsworth, California, had thawed due to depletion of funds by relatives, after being maintained for a year and a half at the personal expense of Nelson. Some of the bodies had apparently thawed years earlier without notification. Nelson was sued, and negative publicity slowed cryonics growth for years afterward. Of 17 documented cryonics cases between 1967 and 1973, only James Bedford remains cryopreserved today. Strict financial controls and requirements adopted in response to the Chatsworth scandal have resulted in the successful maintenance of almost all cryonics cases since that era.
The cryonics organization who was established as a nonprofit organization by Fred and Linda Chamberlain in 1972 as the Alcor Society for Solid State Hypothermia (ALCOR). In 1977, the name was changed to the Alcor Life Extension Foundation. In 1982, the Institute for Advanced Biological Studies (IABS), founded by Mike Darwin and Steve Bridge in Indiana, merged with Alcor. During the 1980s, Darwin worked with UCLA cardiothoracic surgery researcher Jerry Leaf at Alcor to develop a medical model for cryonics procedures. They pioneered the first consistent use of a cryonics procedure now known as a “standby”, in which a team waits to begin life support procedures at the bedside of a cryonics patient as soon as possible after the heart stops.
The oldest incorporated cryonics society still in existence is the American Cryonics Society (ACS). This tax-exempt 501(c)(3) membership organization was incorporated in 1969 as the Bay Area Cryonics Society (BACS) by a group of cryonics advocates that included two prominent Bay Area physicians, M. Coleman Harris and Grace Talbot. The first suspensions under BACS auspices were performed in 1974 by Trans Time, Inc., a for-profit company started by BACS members. BACS researcher Paul Segall, working with Jerry Leaf of CryoVita, developed a medical model to induce hypothermia shortly after pronouncement of death. Segall later went on to pioneer blood substitutes for use in both cryonic suspension and in mainstream medicine.
Cryonics received new support in the 1980s when MIT engineer Eric Drexler started publishing papers and books foreseeing the new field of molecular nanotechnology. His 1986 book, Engines of Creation, included an entire chapter on cryonics applications. Cryonics advocates saw the nascent field of nanotechnology as vindication of their long held view that molecular repair of injured tissue was theoretically possible. In the late 1980s Alcor member Dick Clair (who was dying of AIDS) sued for, and ultimately won for everyone, the right to be cryonically preserved in the State of California. Alcor’s membership expanded tenfold within a decade, with a 30% annual growth rate between 1988 and 1992. But since 2013, membership began to fall after growing discontent and economic reality. (According the Cryonics Magazine of Alcor, July 2013)
On July 24, 1988, a Ph.D. in computer science named Kevin Brown started an electronic mailing list called CryoNet that became a powerful tool of communication for the cryonics community. Numerous other mailing lists and web forums for discussing cryonics and the affairs of particular organizations have since appeared, but CryoNet remained a central point of contact for cryonicists until it was shut down on March 17, 2011.
Alcor was disrupted by political turmoil in 1993 when a group of activists left to start the CryoCare Foundation, and associated for-profit companies CryoSpan, Inc. (headed by Paul Wakfer) and BioPreservation, Inc. (headed by Mike Darwin). Darwin and collaborators made many technical advances during this time period, including a landmark study documenting high quality brain preservation by freezing with high concentrations of glycerol. CryoCare ceased operations in 1999 when they were unable to renew their service contract with BioPreservation. CryoCare’s two patients stored at CryoSpan were transferred to Alcor. Several ACS patients stored at CryoSpan were transferred to CI.
There have been numerous, often transient, for-profit companies involved in cryonics. For-profit companies were often paired or affiliated with non-profit groups they served. Some of these companies, with non-profits they served in parentheses, were Cryonic Interment, Inc. (CSC), Cryo-Span Corporation (CSNY), Cryo-Care Equipment Corporation (CSC and CSNY), Manrise Corporation (Alcor), CryoVita, Inc. (Alcor), BioTransport, Inc. (Alcor), Trans Time, Inc. (BACS), Soma, Inc. (IABS), CryoSpan, Inc. (CryoCare and ACS), BioPreservation, Inc. (CryoCare and ACS), Kryos, Inc. (ACS), Suspended Animation, Inc. (CI, ACS, and Alcor). Trans Time and Suspended Animation are the only for-profit cryonics organizations that still exist.
The cryonics field seems to have largely consolidated around three non-profit groups, Alcor Life Extension Foundation, Cryonics Institute (CI), and the American Cryonics Society (ACS), all deriving significant income from bequests and donations. In 2006, a non-profit called the Cryonics Society was formally incorporated but the group is devoted solely to promotion and public education of the cryonics concept.
As research in the 1990s revealed in greater detail the damaging effects of freezing, there was a trend to use higher concentrations of glycerol cryoprotectant to prevent freezing injury. In 2001 Alcor began using vitrification, a technology borrowed from mainstream organ preservation research, in an attempt to completely prevent ice formation during cooling. Initially the technology could only be applied to the head when separated from the body. In 2005 Alcor began treating the whole body with their vitrification solution in a procedure called "neurovitrification with whole body cryoprotection". In the same year, the Cryonics Institute began treating the head of their whole body patients with their own vitrification solution.
As of November 2014, the Cryonics Institute has 1301 members. At its Clinton Township, Michigan facility, about a fifth of the cryopreserved humans and a smaller portion of the pets came to the CI facility through contract with the American Cryonics Society (which has no storage facilities of its own). As of May 2014, Alcor maintains 124 cryonics patients and about 45 pets in Scottsdale, Arizona. Cryonics Institute and Alcor have support groups in Canada, Europe and Australia. There is also a smaller cryonics company in Russia called KrioRus, which maintains 20 human patients and 10 pets, and the new not-for-profit company Stasis Systems Australia plans to build the first facility in the southern hemisphere. There are also plans being developed by renowned architect Stephen Valentine for a multi-acre futuristic high security facility called Timeship to be built in an undisclosed location in the United States, as well as for an underground facility in Switzerland. Trans Time, a small company, currently maintains 3 cryonics patients.
DARPA currently funds several research projects aimed on sending the human body into a state of suspended animation, essentially “shutting down” the heart and brain until proper care can be administered that can be regarded as a step to cryopreservation of humans.
In popular culture
Suspended animation in fiction is a popular theme in science fiction and fantasy settings, appearing in literature, comic books, films, and television. A survey in Germany found that about half of the respondents were familiar with cryonics, and about half of those familiar with cryonics had learned of the subject from television or film.
The best known cryopreserved patient is baseball player Ted Williams. The urban legend suggesting Walt Disney was cryopreserved is false; he was cremated and interred at Forest Lawn Memorial Park Cemetery. Robert A. Heinlein, who wrote enthusiastically of the concept in The Door into Summer, was cremated and had his ashes distributed over the Pacific Ocean. Timothy Leary was a long-time cryonics advocate, and signed up with a major cryonics provider. He changed his mind, however, shortly before his death, and so was not cryopreserved.
Hal Finney and L. Stephen Coles were cryopreserved in 2014. Among cryopreserved are also James Bedford, Dick Clair, Thomas K. Donaldson, Fereidoun Esfandiary, Jerry Leaf, and John-Henry Williams.
- Alcor Life Extension Foundation
- Chemical brain preservation
- Cryonics Institute
- Indefinite lifespan
- Information-theoretic death
- Life extension
- Suspended animation
- Vitrification in cryopreservation
- McKie, Robin (13 July 2002). "Cold facts about cryonics". The Observer. Retrieved 1 December 2013.
Cryonics, which began in the Fifties, is the freezing - usually in liquid nitrogen - of human beings who have been legally declared dead. The aim of this process is to keep such individuals in a state of refrigerated limbo so that it may become possible in the future to resuscitate them, cure them of the condition that killed them, and then restore them to functioning life in an era when medical science has triumphed over the activities of the Banana Reaper.
- "What is Cryonics?". Alcor Foundation. Retrieved 2 December 2013.
Cryonics is an effort to save lives by using temperatures so cold that a person beyond help by today's medicine might be preserved for decades or centuries until a future medical technology can restore that person to full health.
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- Merkle RC (September 1992). "The technical feasibility of cryonics". Medical Hypotheses 39 (1): 6–16. doi:10.1016/0306-9877(92)90133-W. PMID 1435395.
The extant literature supports but does not prove the hypothesis that cryonics is a feasible method of saving the lives of people who would otherwise certainly die.
- "An open letter to scientific critics of cryonics". Paul Crowley's Blog. Retrieved 2010-02-14.
Though many experts in cryogenics and other relevant fields are quoted in the media as condemning cryonics practice, none have written at greater length to explain their reasons. ... this is my plea to the scientific critics of cryonics: Please criticise cryonics. If you thought that someone else had done it, if you thought that the article you’d want a cryonics hopeful to read had already been written, I hope that the surveys above show you that it really hasn’t.
- "Scientists Open Letter on Cryonics". Retrieved 2013-03-19.
- Lovgren, Stefan (18 March 2005). "Corpses Frozen for Future Rebirth by Arizona Company". National Geographic. Retrieved 15 March 2014.
Many cryobiologists, however, scoff at the idea...
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- Mayford M, Siegelbaum SA, and Kandel ER (April 10, 2012). "Synapses and Memory Storage" (PDF). Cold Spring Harb Perspect Biol. doi:10.1101/cshperspect.a005751.
Procedural and declarative memories differ dramatically. They use a different logic (unconscious vs. conscious recall) and they are stored in different areas of the brain. Nevertheless, these two disparate memory processes share several molecular steps and an overall molecular logic. Both are created in at least two stages: one that does not require the synthesis of new proteins and one that does. In both, short-term memory involves covalent modification of preexisting proteins and changes in the strength of preexisting synaptic connections, whereas long-term memory requires the synthesis of new proteins and the growth of new connections. Moreover, both forms of memory use PKA, mitogen-activated protein kinase (MAPK), CREB-1, and CREB-2 signaling pathways to convert short-term to long-term memory. Finally, both forms appear to use morphological changes at synapses to stabilize long-term memory
- Guyton, Arthur C. (1986). "The Cerebral Cortex and Intellectual Functions of the Brain". Textbook of Medical Physiology (7th ed.). W. B. Saunders Company. p. 658. ISBN 0-7216-1260-1.
We know that secondary memory does not depend on continued activity of the nervous system, because the brain can be totally inactivated by cooling, by general anesthesia, by hypoxia, by ischemia, or by any method, and yet secondary memories that have been previously stored are still retained when the brain becomes active once again. Therefore, secondary memory must result from some actual alterations of the synapses, either physical or chemical.
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Each patient is a free agent entitled to full explanation and full decision-making authority with regard to his medical care. John Stuart Mill expressed it as: `Over himself, his own body and mind, the individual is sovereign.' The legal counterpart of patient autonomy is self-determination. Both principles deny legitimacy to paternalism by stating unequivocally that, in the last analysis, the patient determines what is right for him. ... If the [terminally ill] patient is a mentally competent adult, he has the legal right to accept or refuse any form of treatment, and his wishes must be recognized and honored by his physician.
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The really key idea in cryonics is the idea of freezing (or otherwise preserving) people when we don't know if we can ever revive them.... The cryonics proposal is to treat everyone with these conditions as a permanent patient, until means are found to bring them back to life.
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