Re: virus: Scientists Study Brain Changes Over Time

Date: Thu 19 Dec 2002 - 21:40:22 GMT

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    > Scientists Study Brain Changes Over Time
    > Dec 18, 2:20 PM (ET)
    > Scientists have found a way to track tiny features of individual brain
    > cells in living mice, providing a glimpse at how brains change over
    > time. In one case, they watched the animals' brains rewire after their
    > whiskers were clipped.
    > The technique will help scientists explore how the brain forms
    > memories and reacts physically to its owner's experiences.
    > The advance "will have far-reaching implications" for studying the
    > brain, according to Ole P. Otterson and P. Johannes Helm of the
    > University of Oslo in Norway. They wrote a commentary that accompanies
    > two reports on the technique in Thursday's issue of the journal
    > Nature.
    > Brain cells called neurons signal each other across tiny gaps, called
    > synapses. The signals are received by tiny spines. Researchers in both
    > studies followed the growth and destruction of the spines over time.
    > The researchers tracked the spines, which measure less than one
    > twentieth the width of a human hair, using specially bred mice that
    > carry a gene which makes some of their neurons glow. They used laser
    > and electron microscopes to peek through windows implanted in the
    > mouse skulls, or through skull bones thinned with a drill.
    > In one study, the researchers clipped the highly sensitive whiskers of
    > mice and watched changes in the part of the brain that receives
    > signals from the whiskers. Two to four days after clipping, the number
    > of spines created or lost in that area increased significantly,
    > indicating new synapses were being created and others destroyed, the
    > researchers reported.
    > Graham Knott, a researcher at the University of Lausanne in
    > Switzerland and an author of the study, said the group had for the
    > first time tracked a brain as it adapted to change.
    > "By changing the input to the brain, you've got a situation where
    > you're changing the connections," Knott said.
    > "You knew you would get change... the way in which cells receive the
    > information changes. But to actually look at and see physical changes,
    > that's actually what's happening, you're actually watching the brain
    > connect."
    > Michael Merzenich, a University of California at San Francisco
    > researcher who studies the brain but was not involved in the new
    > research, said the results were expected, but "no one has ever
    > actually watched it happen."
    > In a separate study, researchers at the New York University School of
    > Medicine found that such spines can be long-lived, much longer than
    > the first group found.
    > Spines in the visual cortex, the part of the brain that responds to
    > information from the eyes, lived longer in adult mice than young mice.
    > The NYU group tracked young and adult mice over periods ranging from
    > several hours to several months.
    > The findings suggest some spines can last an entire lifetime, but the
    > NYU researchers said they also found evidence of changes in the shape
    > of individual spines, which could be a means of improving the
    > efficiency of synapses.
    > Larry R. Squire, a neurobiologist at the University of California at
    > San Diego School of Medicine, said the findings of the two studies are
    > not necessarily contradictory because the researchers looked at
    > different parts of the brain using differing techniques.
    > The findings of the two studies also are "some of the best evidence"
    > about how synapses behave in adult mammalian brains and could help
    > explain on how the human brain works, Squire said.
    > "There can be no doubt that similar phenomena occur in the human
    > brain," Squire said.
    > --
    > Walter Watts
    > Tulsa Network Solutions, Inc.
    > "No one gets to see the Wizard! Not nobody! Not no how!"
    > ---
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