Whole-body transplant

A whole-body transplant, or brain transplant, moves the brain of one being into the body of another. It is a procedure distinct from head transplant, which involves transferring the entire head to a new body, as opposed to the brain only. The necessary technology currently does not exist to fully and safely perform this procedure.

Although many scientists would challenge the feasibility of this process, few would say that it is not eventually possible given current research into organ transplant and human cloning. Some bioethicists would argue that there are difficult moral problems involved in either harvesting a brain-dead body, especially one deliberately created using human cloning, or otherwise acquiring a body (say, of a criminal due to be executed for a crime, or an individual who is not dead but is soon to die of a brain-based illness).

Existing challenges
One of the most significant barriers to the procedure is the inability of nerve tissue to heal properly; scarred nerve tissue doesn't transmit signals well (this is the reason a spinal cord injury is so devastating). However, recent research at the Wistar Institute of the University of Pennsylvania involving tissue-regenerating mice may provide pointers for further research as to how to regenerate nerves without scarring.

There is also a potential problem of the new interface at the spinal cord, in that even if all the nerves are connected successfully, they may not transmit the same information as the same nerve connection in the old body. For example, a nerve that used to control the right index finger's muscle group might be connected to a different finger's muscle group, or another body part entirely. If this were to happen to the majority of the connections, the person undergoing the transplant might find themselves in a body which transmitted sensory input to the wrong destination, making it uncomprehendible and requiring many years of rehabilitation.

Also, for the procedure to be practical, the age of the donated body must be sufficient — an adult-sized brain could only fit into the skull of a body at least nine to twelve years old, as that is when the head reaches adult size.

Partial brain transplant
An arguably more reasonable scenario is a partial brain transplant involving only enough tissue to provide key memories and a sense of continuity of identity. A fairly large but indeterminate amount of the brain is devoted to processing and controlling sensory, motor, and autonomic functions such as vision, olfaction, movement, appetite, etc.; if the goal is to move memories and/or identity from one body to another then these portions of the brain are likely both difficult and unnecessary to transplant. The recipient body of such a transplant probably would have to possess a naive and never-conscious brain or partial brain, such as in a never-conscious cloned soma. This possibility provides the basis for I of Persistence, a human life-extension manifesto and science fiction story. One particularly innovative aspect of this story is the concept that the older transplanted brain tissue is eventually removed and replaced with youthful tissue, restoring complete youthfulness, but providing continuity (or persistence) of conscious identity.

In 1982 Dr. Dorothy T. Krieger, chief of endocrinology at Mount Sinai Medical Center in New York City, achieved notable success with a partial brain transplant in mice. A partial brain transplant would accomplish essentially the same goal — movement of a person's "identity" from one body to another — and thus qualify as a whole-body transplant no less than a full brain transplant. As Dr. Krieger demonstrated, barriers to accomplishing this feat might be much lower than transplantation of the entire brain.

Whole-body transplants in popular culture
Transplantation of a human brain from one body into another has appeared on occasion in popular literature. The intended effect is most often either horrific or comedic.


 * The transplant has been a common subject in horror films, most notably Frankenstein.


 * The Ultra-Humanite, one of the main villains opposing the Golden Age Superman and Justice Society of America, often "died" at the end of an encounter, only to have his surviving brain transplanted into a new (not always human) body by robots and/or henchmen.


 * The novel I Will Fear No Evil by Robert A. Heinlein features an elderly multibillionaire who has his brain transplanted into the body of his deceased secretary.


 * The 1983 Steve Martin comedy movie The Man with Two Brains revolves around brain transplantation.


 * In "The Defenseless Dead", a short story by Larry Niven, a criminal tries to hide by this means.


 * The novel Eva by Peter Dickinson focuses on the eponymous 14-year-old girl whose brain is transplanted into the body of a chimpanzee.


 * The premise for the 1999-2000 TV program Now and Again was the transplantation of lead character Michael Wiseman's brain into a genetically-engineered body to make him into a top-secret super-agent.


 * On the fictionalized version of the TV program Days of our Lives as shown on Friends, Dr. Drake Ramoray, the character played by Joey Tribbiani (Matt LeBlanc), is resurrected for the show by means of a brain transplant.


 * The novel My Brother's Keeper by Charles Sheffield is based on a partial brain transplant. Identical twins suffer major injuries in a crash, including damage to one side of each of their heads.  One twin is dying from the loss of vital organs, so a surgeon saves part of his brain by using it to replace part of his brother's.


 * In the 2006 Cartoon Network movie Re-Animated, the main character Jimmy Roberts (Dominic Janes) has to receive an emergency brain transplant because of a freak accident. He receives the brain of the late Milt Appleday (a parody of Walt Disney), and can see cartoon characters with his new brain.


 * In the Australian novel Spare Parts, C-class citizens sell their bodies to the wealthy elite who wish to transplant their brains into younger, better-looking bodies. The main character Kelty sells her body in order to become a cyborg.

Similar concepts
The whole-body transplant is just one of several means of putting a consciousness into a new body that have been explored by both scientists and writers.

A similar procedure often found in science fiction is the transfer of one consciousness to another without moving the brain. This is found in many sources, most often a body swap between two characters of an ongoing television series; it occurs in the original Star Trek series twice, as well as Farscape, Stargate SG-1, Buffy the Vampire Slayer, and many others. Since there is no movement of the brain(s), however, this is not quite the same as a whole-body transplant.

Similar in many ways to this is the idea of mind uploading, promoted by Marvin Minsky and others with a mechanistic view of natural intelligence and an optimistic outlook regarding artificial intelligence. It is also a goal of Raëlism, a small cult based in Florida, France, and Quebec. However, while 'transplanting' sees the ultimate goal as being a new body optimized for that brain by genetics, proteomics, and/or other medical procedures and a transfer of the brain to that body, in the almost equally speculative procedure of 'downloading', the brain itself moves nowhere and may even be physically destroyed or discarded; the goal is rather to duplicate the information patterns contained within the brain.

Another similar literary theme, though different from either procedure described above, is the transplanting of a human brain into a mechanical, usually robotic, body. Examples of this include Robocop; the DC Comics superhero Robotman; full-body cyborgs in manga and anime series Ghost in the Shell; or the Cybermen from the Doctor Who television series. In Star Trek, the episode "Spock's Brain" involves transplantation of the eponymous organ into a large computer-like structure, and in "I, Mudd" Uhura is offered immortality in an android body.