A whole-body transplant or brain transplant is a hypothetical operation in which the brain of one being is transplanted 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. Theoretically, a person with advanced organ failure could be given a new and functional body while keeping their own personality and memories.
Historically, whole-body transplants have not been feasible and were widely regarded as impossible. Today, given progress in organ transplant and human cloning research, many scientists hold that whole-body transplants are theoretically possible and likely to be feasible in the future.
Whole-body transplants and similar concepts have been explored in various forms of fiction.
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One of the most significant barriers to the procedure is the inability of nerve tissue to heal properly; scarred nerve tissue does not transmit signals well (this is why a spinal cord injury is so devastating). However, recent research at the Wistar Institute of the University of Pennsylvania involving tissue-regenerating mice (known as MRL 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 still be connected wrongly, in some cases, thus not transmitting 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 a large number of connections, the person undergoing the transplant might end up with a body which transmitted sensory input to the wrong destination, making it incomprehensible and potentially requiring many years of rehabilitation.
Also, for the procedure to be practical, the age of the donated body must be sufficient: an adult brain cannot fit into a skull that has not reached its full growth, which occurs at age 9–12 years.
There is an advantage however, the brain is an immunologically privileged organ, so rejection would not be a problem, unlike other organs, say the liver, which is usually aggressively rejected by the host's immune system.[1][2]
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.; transplanting these portions is likely to be difficult and, if the goal is to transfer memories and/or identity, unnecessary. The recipient body of such a transplant probably would have to possess a naïve and never-conscious brain or partial brain, such as in a never-conscious cloned soma. This is the premise of I of Persistence, a human life-extension manifesto and science fiction story. In that story, the older transplanted brain tissue is eventually removed and replaced with youthful tissue, restoring complete youthfulness with 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.[3] A partial brain transplant could 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.
In 1998, a team of surgeons from the University of Pittsburgh Medical Center attempted to transplant a group of brain cells to Alma Cerasini, who had suffered a severe stroke that caused the loss of mobility in her right limbs as well as limited speech. The team's hope was that the cells would correct the listed damage.
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, though many of these stories explore the medical, ethical, legal, and other issues that would surround the procedure.
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 Freaky Friday, Farscape, Stargate SG-1, Buffy the Vampire Slayer, Dollhouse, Red Dwarf, Avatar; even in Archie comics. Since there is no movement of the brain(s), however, this is not quite the same as a whole-body transplant.
In horror, the film The Skeleton Key has the protagonist, Caroline, discover that the old couple she is looking after are really poor black Voodoo witch doctors, Mama Cecile and Papa Justify, who stole the bodies of two young privileged white children in their care using a ritual which allows a soul to swap bodies. Unfortunately the evil old couple also trick Caroline and their lawyer, Luke, into falling foul of the same procedure and both end up stuck in old dying bodies unable to speak while the witch doctors walk off with their young bodies. The theme of stealing another persons body is also repeated in the book The Tale of the Body Thief by Anne Rice. In this case the vampire Lestat discovers a man, Raglan James, who can will themselves into another persons body. He demands that the procedure is used on him to allow him to revert to being human once again. However, Lestat soon realises he has made an error and is forced to recapture James in his vampiric form so he can take his body back.
In the Star Wars Expanded Universe, Emperor Palpatine is able to transfer his consciousness into clone bodies. In a sense, this allows him to return to life after the Battle of Endor, as well as other events where his current body dies. The clone bodies aren't quite as good as his original body and waste quickly due to the decaying power of the Dark Side of the Force. Upon realizing this, he tries to take of the body of Anakin Solo, but is unsuccessful and eventually meets his final end.
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 an artificial, usually robotic, body. Examples of this include: Caprica; Fullmetal Alchemist; Ghost In The Shell; RoboCop; the DC Comics superhero Robotman; the Cybermen from the Doctor Who television series; the cymeks in the Legends of Dune series; or full-body cyborgs in many manga or works in the cyberpunk genre. 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. The novel Harvest of Stars by Poul Anderson features many central characters who undergo such transplants, and deals with the difficult decisions facing a human contemplating such a procedure.
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