textfiles/bbs/KEELYNET/BIOLOGY/brain1.asc

   

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