Date: Thu 19 Dec 2002 - 21:40:22 GMT
> Scientists Study Brain Changes Over Time
> Dec 18, 2:20 PM (ET)
> By ALEX DOMINGUEZ
> 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
> 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
> 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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