Received: by alpheratz.cpm.aca.mmu.ac.uk id DAA15492 (8.6.9/5.3[ref pg@gmsl.co.uk] for cpm.aca.mmu.ac.uk from fmb-majordomo@mmu.ac.uk); Wed, 14 Mar 2001 03:13:44 GMT Subject: Fwd: Toggling nature's auto-erase Date: Tue, 13 Mar 2001 22:10:01 -0500 x-sender: wsmith1@camail2.harvard.edu x-mailer: Claris Emailer 2.0v3, Claritas Est Veritas From: "Wade T.Smith" <wade_smith@harvard.edu> To: "Memetics Discussion List" <memetics@mmu.ac.uk> Content-Type: text/plain; charset="iso-8859-1" Content-transfer-encoding: quoted-printable Message-ID: <20010314031002.AAA22459@camailp.harvard.edu@[205.240.180.26]> Sender: fmb-majordomo@mmu.ac.uk Precedence: bulk Reply-To: memetics@mmu.ac.uk
Toggling nature's auto-erase
Mice tests show how gene controls a memory feature
By Richard Saltus, Globe Staff, 3/9/2001
http://www.boston.com/dailyglobe2/068/nation/Toggling_nature_s_auto_eraseP.
shtml
orgetting too much can be bad, but remembering too much can also be a
handicap.
Evolution equipped the brains of animals with an automatic-erase feature
that prevents a torrent of trivial events from clogging long-term memory.
Now, scientists have shown they can switch this device off and on in
mice. When it is disabled, the mice perform feats of superior learning
and memory. Switched back on, the rodents become pedestrian learners
again.
Dr. Eric R. Kandel, a Nobel laureate neuroscientist at Columbia
University, headed a team that's reporting the memory advance in today's
issue of the journal Cell.
''I think this is one of a number of steps toward finding targets in the
brain'' for future drugs to improve or restore memory, Kandel said in an
interview.
Larry Squire, a memory researcher at the University of California in San
Diego, agreed but cautioned that tinkering with nature's balance of
memory and forgetting could be risky.
''It's been said that a better memory isn't necessarily an optimal
memory; you can remember too much,'' Squire said in a telephone
interview. ''But if you have people with failing memories, that's a
different story.''
Kandel, whose coauthors included Gael Malleret at Columbia and Isabelle
M. Mansuy of the Swiss Federal Institute of Technology, said the brain is
regulated by molecular switches that can make memories easier or harder
to form. Memories are processed for storage in a part of the brain called
the hippocampus.
A molecule called calcineurin is the key player in the balance of brain
chemicals that determines whether a thought vanishes instantly or gets
encoded as a long-term memory. The more active calcineurin is, the harder
it is for the hippocampus to store a thought. When calcineurin is less
active, thoughts become memories more easily.
Kandel's team bred mice with a foreign gene that could be turned on and
off by giving the rodents a common antibiotic, doxycycline. The gene made
calcineurin more or less active.
Then they compared the performance of those mice and normal mice on
standard memory tests. In one set of tests, the mice were shown a novel
object, and the mice, by their behavior, indicated how long they
remembered it was new to them.
In another set of tests, mice had to learn and remember how to swim to a
submerged, hidden platform that allowed them to stand safely in a water
bath.
When mice were given doxycycline and their calcineurin was turned down by
the gene switch, they learned faster and remembered longer, said the
report. For as long as a week after the experiment, the mice that
received the drug remembered the object was new. But by two weeks, the
memory had faded.
Then the scientists ended the dosage of doxycycline, which allowed
calineurin to be more active and memories harder to form. Given the same
test, the mouse no longer had superior memories.
''I would call this a real but modest enhancement of memory,'' said
Kandel. The genetic switching didn't improve extremely long-term memory,
and it didn't affect so-called working memory, holding two or three
things in mind while performing a task.
Kandel next wants to test the system on aging mice, to determine whether
blocking calcineurin will prevent the erosion of memory with age.
This story ran on page 4 of the Boston Globe on 3/9/2001. © Copyright
2001 Globe Newspaper Company.
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