Many people donate the organs from the body of their deceased loved ones to help save lives. But how would they feel if that body came back to life, but someone else was inside it?
This is, in theory, what would happen in a brain transplant. More accurately, this procedure, which involves replacing a nonfunctional brain with another person’s working brain, would be called a full-body transplant; the brain is given a new body, rather than the body is given a new brain, because the brain is what contains the personality and memories of a person.
Many science fiction novels and movies depict a brain transplant as a simple, innovating procedure that plops a brain into new head and leaves behind only a scar on the back of the head. However, it’s not as easy as that. There are many stumbling blocks that scientists must cross before they can even approach attempting this type of surgery.
The first obstacle is the inability of nerve tissue to regenerate. Cutting the brain out of its safe home (consisting of three meninges layers, cerebrospinal fluid, and the skull) would surely harm some of the surrounding nerves. For the same reason that a spinal cord injury is so devastating, the brain would not function properly because the neurons would not properly send their electrical signals.
Another problem is the possibility of organ rejection. This occurs when the transplanted tissue/organ is rejected by the recipient’s immune system. Because the new tissue doesn’t perfectly match the original tissue, the recipient’s antibodies attempt to kill the foreign substance. However, because significant progress has been made to prevent organ rejection in heart and kidney transplants, scientists could apply similar methods in a brain/fully body transplant.
One obstacle that could be overcome is the disconnection of the brain from the sensory nerves and blood surrounding the brain. Although a little more grotesque, this could be avoided by transplanting a head rather than a brain. A head transplant would reduce the dangers involved with reconnecting the brain to the sensory organs and blood vessels of the head. In fact, in 1970, Dr. Robert White and his colleagues transplanted the head of a Rhesus monkey onto the body of a similar, decapitated monkey (see video below).
Currently, however, the greatest challenge faced by scientists attempting a head or brain transplant is the spinal cord. There is no way to reconnect a severed spinal cord to the brain; transplanting the cord along with the head won’t work either, because the peripheral nervous system (consisting of all the branches of nerves extending to all parts of the body) is connected to it. If the head/full body transplant was carried out, the resultant human would be a quadriplegic, or tetraplegic, meaning that he/she would be paralyzed from the neck down. It is doubtful that this condition would be better than the head’s original body. However, Dr. Sergio Canavero of the Turin Advanced Neuromodulation Group says that the spinal cord does, in fact, have a chance; by “cleanly” cutting off the head, it can be attached to the donor body by using special adhesives, such as polyethylene glycol (PEG). This would “glue” and connect the matching vessels, nerves, and spinal cord. Unsurprisingly, most surgeons and researchers are skeptical of this method, even calling it a “fantasy” and “bad science.”
In addition to the obstacles concerning brain transplants, there is much controversy over its moral and ethical implications. One thing’s for sure though: even though this surgery could one day become possible, you won’t be seeing a mix-match of bodies and heads anytime soon!