Meir,
   this is so interesting. getting to see stuff like
this before they hit the news is the only thing i
really miss after retiring from the CDC.
   speaking of memories, i am going to post a problem
with my memory and another unrelated problem that has
me somewhat concerned. maybe some of you can then give
me your thoughts. it seems that this group always has
someone with knowledge of anything that gets out on a
post.

--- Meir Weiss <[log in to unmask]> wrote:
> -----Original Message-----
> From: NIH news releases and news items
> [mailto:[log in to unmask]] On
> Behalf Of NIH OLIB (NIH/OD)
> Sent: Wednesday, May 12, 2004 12:07
> To: [log in to unmask]
> Subject: STUDY ALLOWS RESEARCHERS TO VISUALIZE
> FORMATION OF A MEMORY
>
>
> U.S. Department of Health and Human Services
>
> NATIONAL INSTITUTES OF HEALTH
>
> NIH News
>
> National Institute of Neurological Disorders and
> Stroke
> http://www.ninds.nih.gov/
>
> EMBARGOED FOR RELEASE
> Wednesday, May 12, 2004
> 12:00 p.m. ET
>
> CONTACT:
> Natalie Frazin
> or Paul Girolami
> 301-496-5924
>
>
> STUDY ALLOWS RESEARCHERS TO VISUALIZE FORMATION OF A
> MEMORY
>
> For the first time, researchers have used a
> technique
> called optical imaging to visualize changes in nerve
> connections when
> flies learn. These changes may be the beginning of a
> complex chain of
> events that leads to formation of lasting memories.
> The study was funded
> in part by the NIH's National Institute of
> Neurological Disorders and
> Stroke (NINDS) and appears in the May 13, 2004,
> issue of "Neuron".*
>
> Scientists have long been captivated by the
> questions of
> how memories form and how they are represented in
> the
> brain. The answers to these questions may help
> researchers understand
> how to treat or prevent memory problems, drug
> addiction, and other human
> ailments. Thousands of changes in gene expression,
> neuron formation,
> nerve signaling, and other characteristics may be
> involved in the
> formation of just a single memory. Scientists refer
> to any learning-
> induced change in the brain as a "memory trace."
>
> In the new study, Ronald L. Davis, Ph.D., and
> colleagues at Baylor
> College of Medicine in Houston developed fruit flies
> with special genes
> that caused the flies' neuronal connections to
> become fluorescent during
> nerve signaling (synaptic transmission). They then
> exposed the flies to
> brief puffs of an odor while they received a shock.
> This caused them to
> learn a new association between the odor and the
> shock - a type of
> learning called classical conditioning.
>
> Using a high-powered microscope to watch the
> fluorescent signals in
> flies' brains with as they learned, the researchers
> discovered that a
> specific set of neurons, called projection neurons,
> had a greater number
> of active connections with other neurons after the
> conditioning
> experiment. These newly active connections appeared
> within 3 minutes
> after the experiment, suggesting that the synapses
> which became active
> after the learning took place were already formed
> but remained "silent"
> until they were needed to represent the new memory.
> The new synaptic
> activity disappeared by 7 minutes after the
> experiment, but the flies
> continued to avoid the odor they associated with the
> shock.
>
> This is the first time that optical imaging has been
> used
> to visualize a memory trace, Dr. Davis says. "It's
> phenomenally powerful, like a movie appearing in
> front of
> you," he adds. The study suggests that the earliest
> representation of a
> new memory occurs by rapid changes - "like flipping
> a switch" - in the
> number of neuronal connections that respond to the
> odor, rather than by
> formation of new connections or by an increase in
> the number of neurons
> that represent an odor, he adds.
>
> The fact that the flies continued to show a learned
> response even after the new synaptic activity waned
> suggests that other memory traces found at higher
> levels in
> the brain took over to encode the memory for a
> longer
> period of time, Dr. Davis suggests. If so, the rapid
> changes of nerve transmission that the researchers
> saw may
> be the all-important switch that initiates the
> formation of
> new memories.
>
> This research suggests a previously unknown
> mechanism for
> how memories are formed, Dr. Davis says. While this
> study looked only at
> learning related to odors, this newly identified
> process may be at work
> in many other kinds of learning as well. It is
> likely that these or
> similar mechanisms are important for memory in
> humans and other animals,
> he adds.
>
> "This is a remarkable study which uses molecular
> genetic approaches to
> visualize memory formation in a living organism. It
> demonstrates that,
> in this model system, short term memory involves the
> recruitment of new
> synaptic connections into pre-existing ensembles of
> synapses. It will be
> critical to determine whether similar principles
> control memory
> formation in higher organisms," says Robert
> Finkelstein, Ph.D., a
> program director at NINDS.
>
> The researchers now plan to put fluorescent genes
> into a variety of
> other neurons of the brain in order to determine
> which ones respond to
> different kinds of stimuli. This will allow them to
> learn how the
> changes they identified affect higher-level neurons.
> They also hope to
> begin studying similar mechanisms in other animal
> models, such as mice.
>
> The NINDS is a component of the National Institutes
> of
> Health within the Department of Health and Human
> Services
> and is the nation's primary supporter of biomedical
> research on the brain and nervous system.
>
> --------------------------------------------
>
> *Yu D, Ponomarev A, Davis RL. "Altered
> representation of
> the spatial code for odors after olfactory classical
> conditioning: memory trace formation by synaptic
> recruitment." 'Neuron', May 13, 2004, Vol. 42, No.
> 3, pp. 437-449.
>
> ##
>
> This NIH News Release is available online at:
> http://www.nih.gov/news/pr/may2004/ninds-12.htm
>
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