http://news.yahoo.com/s/hsn/20081022/hl_hsn/scientistserasespecificmemoriesinmice
Scientists Erase Specific Memories in Mice
By Alan Mozes
HealthDay Re****ter by Alan Mozes
healthday Re****ter – Wed Oct 22, 7:03 pm ET
WEDNESDAY, Oct. 22 (HealthDay News) -- It sounds like science fiction, by
scientists say it might one day be possible to erase undesirable memories
from the brain, selectively and safely.
Using a complex genetic approach, U.S. and Chinese researchers believe
they
have done just that in mice, but the feat is far from being tested on
humans.
Study co-author Joe Z. Tsien, co-director of the Brain & Behavior
Discovery
Institute at the Medical College of Georgia, Augusta, says the "work
reveals
a molecular mechanism of how [memory deletion] can be done quickly and
without doing damage to brain cells."
The finding is published in the Oct. 23 issue of Neuron.
Humans plagued by painful memories have long wished for a way to eject
them
from the brain. The concept was the premise of the popular 2004 film
Eternal
Sun****ne of the Spotless Mind, in which two former lovers pay a "memory-
erasure" service to expunge the unhappy affair from their minds.
To explore the possibility of safely carving away bits of memory, the
study
authors first focused on the activity of a common protein found only in
the
brain, called CaMKII.
In both mice and people, this enzyme is often referred to as the "memory
molecule" because of its key role in facilitating brain cell communication
--
especially people's ability to learn and retain information.
To hone in on the specific workings of CaMKII, Tsien and his team first
developed a "chemical-genetic method" that enabled them to instantly turn
the
protein "on" or "off" among mice intentionally bred to overproduce the
molecule.
After exposing the mice to emotionally powerful stimulations, such as a
mild
shock to their paws, the scientists then observed how well or poorly the
animals subsequently recalled the particular trauma as their brain's
expression of CaMKII was manipulated up and down.
When the brain was made to overproduce CaMKII at the exact moment the
mouse
was prodded to retrieve the traumatic memory, the memory wasn't just
blocked,
it appeared to be fully erased.
This occurred without impacting the animal's ability to recall any other
memories, the scientists say.
A similar observation was made in experiments involving the mice's
recognition of specific objects. In those cases, overexpression of CaMKII
appeared to eliminate all memory of toys with which the mice had
previously
been exposed.
According to Tsien, the animal study illustrates how the targeted erasure
of
specific memories might be genetically triggered in a controlled and
harmless
manner.
The authors stressed that their work is in its infancy, but they believe
it
opens up the theoretical possibility of therapeutic applications for
humans
down the road. Memory erasure might help relieve trauma among people
plagued
by fearful memories, such as those with post-traumatic stress disorder
(PTSD), for example.
"While memories are great teachers and obviously crucial for survival and
adaptation, selectively removing incapacitating memories, such as
traumatic
war memories or an unwanted fear, could help many people live better
lives,"
Tsien said.
However, Dr. Joe Verghese, an associate professor of neurology at the
Albert
Einstein College of Medicine in New York City, cautioned that the animal
work
described in the study remains preliminary.
"I think the idea of selectively targeting memory processes is very
interesting," he said, "because it not only opens up a whole area of
possible
intervention but also reveals something about the neurobiology that goes
into
creating memory in the brain."
"But memory in a human is much more complex than a memory in a mouse,"
Verghese added. "So, this experimental model, while it brings to mind all
sorts of possible applications, is many steps removed from any human
application."
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