134 lines
6.1 KiB
Plaintext
134 lines
6.1 KiB
Plaintext
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This news article was taken from the Dallas Times Herald, Wednesday,
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November 1, 1989. The article originated from the Los Angeles Times.
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SCIENTISTS PROVE BRAIN THEORY
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(Computer-like `hard-wiring' allows cells to store memories)
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LOS ANGELES - Researchers at the University of Southern
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California and the University of Illinois Have for the first time
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experimentally confirmed the longstanding theory that the brain stores
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memories by "hard-wiring" new connections between groups of brain
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cells.
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Their results, to be reported today at a meeting of the Society
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for Neuroscience in Phoenix, Ariz. are the culmination of decades of
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research for the physical mechanisms underlying the mysterious process
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by which the brain stores memories.
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In two separate sets of experiments involving rats and rabbits,
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the researchers clearly identified memory-related changes in the
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physical links among groups of brain cells, or neurons. The changes
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occurred when the animals learned specific physical activities, such
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as blinking an eye in response to the ringing of a bell or learning to
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walk along an elevated pathway.
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The experiments offer an explanation for why some types of
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learned behavior, such as the ability to ride a bicycle, are never
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forgotten. The reason is that the necessary muscle commands for
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riding a bicycle, for instance, are hard-wired into brain cells in the
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same way that some commands for operating a computer are permanently
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stored by wiring transistors together.
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"In terms of vertebrates, we really haven't had any direct
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information about anatomical changes related to specific learning
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events," said neuroscientist Lawrence R. Squire of the Veterans
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Affairs Hospital in San Diego. "This will greatly increase our level
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of certainty" about how memories are formed, he added.
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Psychobiologists Richard F. Thompson of USC and William Greenough
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of Illinois have been studying a so-called Pavlovian response in
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rabbits. The technique is named after Russian physiologist Ivan
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Pavlov, who rang a bell every time he fed a group of dogs. After
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training, the dogs began to salivate evert time the bell was rung,
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even if they were not given food.
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Thompson rang a bell every time he directed a mild puff of air
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into one eye of rabbits, causing them to blink. After training, the
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rabbits would blink every time the bell was rung.
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Implanting microelectrodes throughout the brain, Thompson and his
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colleagues found that the learned blinking was controlled by a small
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group of cells, called Purkinje cells, in the cerebellum, which is the
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brain's coordinating center for muscular activity. When they
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surgically removed the small group of Purkinje cells, the animals no
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longer blinked.
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Thompson then turned the trained animals over to Greenough, whose
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specialty is looking for signs of increased connections between brain
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cells.
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Page 1
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In previous studies with rats, Greenough had shown that rats
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raised in an "enriched" environment - one with lots of toys and other
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mentally stimulating objects - have a much greater number of
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intercellular connections then those raised in a more sterile
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environment. In those cases, however, the increased connections could
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not be associated with specific memories.
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In the new study, Greenough and his students studied the number
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of intercellular connections in the specific area of the cerebellum
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that Thompson had shown controlled the eye-blink behavior. They
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compared the number of connections in this area to the number on the
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opposite side of the cerebellum, controlling the eyelid that was not
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trained, and found a significant difference.
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In the 15 rabbits studied over a two-year period,
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"The differences were statistically reliable and clearly visible,"
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Greenough said. "We really have isolated a case where, in brain
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cells that are clearly involved in the performance of a task, we
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have crystal clear [structural] change that indicated a change in
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anatomical circuitry."
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The discovery of altered numbers of connections, Thompson added,
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"is not surprising, in that it fits theory, but there has been no
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particular evidence [to support the theory] before. We were
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convinced there would be something like this because memories are
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never forgotten."
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The cerebellums of all mammals are remarkably similar, Greenough
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noted, and researchers are confident that discoveries made in animal
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brains are applicable to humans. They also believe that the mechanism
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used for storing memories involved with muscle movements will be
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similar, if not identical to, those involved in storing other types of
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memories.
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Thompson noted that the brain has the potential for "trillions
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and trillions" of such physical connections, so that the physical
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structure of the brain does not limit the number of things that can be
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remembered.
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Both Thompson and Greenough caution that researchers are only
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beginning to unravel the mechanism of memory formation. "This is a
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major advance," Greenough said, "but it is only a first step that
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leads to a lot more research rather then a last step that wraps
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everything up."
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{Gee Wiz it's amazing how medical science is advancing! Just
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think that maybe they will discover that magnetic energies can
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effect the BRAIN !!! }
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R.B.
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Page 2
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