Word: braine
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Dates: during 1990-1999
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...Whole-brain transplants are still science fiction. "I never like to say that something's impossible," says Dr. Evan Snyder, a neuroscientist at Harvard Medical School and Children's Hospital in Boston. "I've been burned too many times by categorically ruling something out. And yet I can't imagine that 20 years from now human-brain transplants will be possible. The connections required are just too complex; they number in the millions. But the future of brain-cell transplants--that's another matter...
...medical science has had only mixed results with brain-cell transplants. Take the treatment of Parkinson's disease, for example, a condition that is gradually depriving more than 1 million Americans of their ability to move and speak. The disease is caused by the slow deterioration of brain cells that produce dopamine, a chemical essential for the transmission of messages from the brain to the rest of the body. A decade ago, Swedish researchers started implanting dopamine-producing cells from human fetuses into the brains of Parkinson's patients. The treatment improved the mobility of many of the patients...
...Decade of the Brain proclaimed by President George Bush draws to a close, neuroscientists are increasingly sanguine that in George Jr.'s lifetime, brain-cell transplants may reverse, if not cure, a host of neurological diseases such as Parkinson's and Alzheimer's, as well as brain damage caused by strokes and head injuries. Even a year ago, such a sweeping claim might have been dismissed as nonsense. But that was before last fall's discovery that the fetal human brain contains master cells (called neural stem cells) that can grow into any kind of brain cell. Snyder extracted these...
When most physicians got their training, they were taught that the adult brain is rigid, that its nerve cells, or neurons, could never regenerate themselves. If you nick your finger with a knife, the cut will heal in a few days because your skin has the ability to generate new cells. But when something bad happens to the brain, it doesn't repair itself. Why's that? "The brain is not plastic," says Snyder. "It doesn't make new cells. You are born with more brain cells than you need, and you lose them progressively and get dumber and dumber...
...path to overturning the dogma of the rigid brain was circuitous. In the early 1960s biologists discovered that new cells were being made in two areas of the adult rat brain, but the discovery was regarded as an unimportant peculiarity of the rodent brain and quickly forgotten. In the mid-1980s, Fernando Nottebohm of Rockefeller University brought new respect to the term birdbrain by demonstrating that the brain of an adult canary has the astonishing ability to regenerate new nerve cells at a rate of up to 20,000 a day. Other researchers reported similar regenerative ability in fish...