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A brain transplant or whole-body transplant is a procedure in which the brain of one organism is transplanted into the body of another. It is a procedure distinct from head transplantation, 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, memories, and consciousness. Historically, only one brain transplant was conducted by neurosurgeon Robert J. White; he transplanted the brain of a monkey into the neck of another monkey. EEG readings showed the brain was later functioning normally. It was thought to prove that the brain was an immunologically privileged organ, as the host's immune system did not attack it at first,〔http://www.washingtoncitypaper.com/articles/45154/what-would-happen-in-a-brain-transplant-personalities-bodies-and/〕 but immunorejection caused the monkey to die after nine days.〔()〕 Brain transplants and similar concepts have also been explored in various forms of science fiction. == Existing challenges == 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. Alternatively a brain–computer interface can be used connecting the subject to their own body. A study〔C. Ethier, E. R. Oby, M. J. Bauman, L. E. Miller: (Restoration of grasp following paralysis through brain-controlled stimulation of muscles ). ''Nature'', April 2012.〕 using a monkey as a subject shows that it is possible to directly use commands from the brain, bypass the spinal cord and enable hand function. An advantage is that this interface can be adjusted after the surgical interventions are done where nerves can not be reconnected without surgery. 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 was at first thought to be an advantage, however, with respect to the immune response. The brain was thought to be an immunologically privileged organ, so rejection would not be a problem. (When other organs are transplanted, aggressive rejection can occur; this is a major difficulty with kidney and liver transplants. However, immune cells of the CNS contribute to the maintenance of neurogenesis and spatial learning abilities in adulthood, so the transplanted brain would not be unhindered from the transplant.〔Ziv, Y.et al (2006). Nature Neuroscience, Immune cells contribute to the maintenance of neurogenesis and spatial learning abilities in adulthood 9, 268 - 275.〕)〔Lou Jacobson: (A Mind is a Terrible Thing to Waste ). ''Lingua Franca'', August 1997.〕〔Mike Darwin: (But What Will The Neighbors Think? A Discourse On The History And Rationale Of Neurosuspension ). ''Cryonics'', October 1988.〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Brain transplant」の詳細全文を読む スポンサード リンク
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