Download Purplechocolatebubblegum

Purplechocolatebubblegum
12/18/09
Erasing Fear Memories: “Fear Training”
What do sexual assaults, plane crashes, torture, and natural disasters have in common?
Besides the fact that they are all devastating for those affected by it, they can also can cause
trauma, an emotional wound or shock. Post Traumatic Stress Disorder, or PTSD, is an anxiety
disorder that often affects those who have been through such a traumatic event. Research
shows that PTSD is most severe and long lasting when the traumatic event is a deliberate manmade disaster, and that veterans who experience war-related traumatic events usually exhibit
significantly more PTSD symptoms than average patients do. (August & Gianola, 1987). Some
patients with this disorder constantly have to relive their trauma through flashbacks or
nightmares, and others become emotionally detached, willfully avoiding objects or events that
are reminders of their experience, or suffering from extreme guilt, depression, and worry. Such
relapses of these “fear memories” of traumatic events posed major clinical problems, as up until
recently they were thought to be impossible to eliminate (Pizzorusso, 2009; Hupbach et al.,
2009). New neurobiological findings, however, have discovered a way to eliminate sporadic
reoccurrences of fear memories in rats, which gives scientists much hope about treating
disorders like PTSD in the future.
One of the biggest obstacles in the treatment of PTSD and other related syndromes is
that once fear memories become consolidated in the brain, they become permanently erasureresistant (Pizzorusso, 2009). That means that these fearful memories arenearly impossible to get
rid of, or protected in the brain by the netlike proteins called chondroitin sulfate proteoglycans
(Gogolla et al., 2009). Thus, an important new step in the neurobiological field is the discovery
that although these memories were impossible to be erased, they were not necessarily
unchangeable. It was discovered that before the fear memories were consolidated, or became
permanent, there was a time period where they were initially fragile and subject to change.
Every subsequent time that this painful memory is “retrieved”, or revisited, the protein that is
responsible for keeping the memory stable is degraded, or broken down (Lee et al., 2008). Thus,
this memory returns to its flexible state, and it can be modified for a window of time until the
protein is reconsolidated in the brain and placed in long term storage (Hupbach et al., 2009).
Some scientists say that this serves to incorporate new information about a specific fear in order
to update an original memory (Lee et al., 2008). This new finding has made neurobiologists
excited about its many possible applications in the treating of anxiety disorders like PTSD.
One experiment tested whether this process could be effective without the use of
drugs. Specifically, this experiment (Monfils et al., 2009) wanted to see if the rats’ memories
could be trained to tone down the fear that was associated with a footshock. To do this, first,
the rats were zapped three times with a shock to their feet while simultaneously hearing a
specific tone. Then, the rats were made sure to have associated the tone with the shock; every
subsequent time they heard the tone,even without receiving the shock, their bodies froze as a
result of fear. Afterwards, the tone was played for the rats again, “retrieving” the original
memory- and also rendering that memory unstable. Immediately afterwards, during the window
of instability, the tone was constantly played for the rats (without the shocks), until habituation
in effect occurred (which means that the tone was played so many times without any danger
taking place that there was a decrease in the fear response, or freezing, to the tone), without
any danger taking place. Then, when the memory’s period of instability ended and the memory
was reconsolidated, the new information that the tone was harmless was also solidified into the
brain along with the original memory. The rats’ lack of reaction to the tone was held 24 hours, a
week, and even a year after the training, even when the shock was given again unexpectedly.
This experiment shows that even without the use of drugs, a kind of clinical therapy can be done
to rats during the time period of instability of a recalled memory to reduce their reaction to an
associated fear, in this case, to the tone.
In another experiment, a trio of Dutch researchers tested the same concept on humans.
In this experiment (Kindt et al., 2009), human subjects were shown pictures of spiders, with
each image accompanied by an electric shock. Then, the following days, the scientist redisplayed
the images to the subjects, either with or without orally pre-administering a propranolol, an
anti-adrenaline drug. The intended effect of the a propranolol was to interfere with the action of
stress hormones on the body and brain, causing the fear reaction. In this case, the subjects'
fearful emotions were diminished, while their memory of events remained intact. It was found
that those who had taken a propranolol prior to viewing the image had a far weaker startle
response when exposed to the images than those who had not. (Startle responses were due to
expecting a shock after viewing the spider images). The experimenters concluded that the drug
interfered with the reconsolidation of the emotional part of the memory. Thus, although they
clearly remembered what had happened (that they received shocks while viewing the spider
images), they ceased to feel fear even when exposed to the stimulus, or the spidery images.
Of course, such findings do not guarantee a flawless therapeutic method for treating
disorders like PTSD. However, recent discoveries and findings have given hope to both
researchers and therapists alike. These experimental successes have encouraged researchers to
further the test if such treatments, such as the application of propranolol after memory
retrieval, are effective ways to treat these emotional disorders in the clinic, and to prevent the
relapse of fear. Hopefully, these experiments will one day lead to a trenchant way to treat those
suffering from PTSD.
Peer reviewer: chocolove
Comments:
I think overall, your paper is good except for the fact that you are making the sentences too
complicated. However, your grammar seems fine although you had some unnecessary
sentences and inconsistent verb phrases. Also, I think you could have made your introduction a
little shorter because if the introduction is too long, readers will soon get bored or tired of
reading your paper. Nonetheless, great job!
August, L. R., & Gianola, B. A. (1987). Symptoms of War Trauma Induced Psychiatric Disorders:
Southeast Asian Refugees and Vietnam Veterans.
IMR, 21(3) , 1017-1020.
Gogolla, N., Caroni, P., Luthi, A., & Herry, C. (2009). Perineuronal Nets Protect Fear Memories
from Erasure. Science, 325, 1258-1261.
Hupbach, A., Gomez, R., & Nadel, L. (2009). Episodic Memory Reconsolidation: Updating or
Source Confusion. Memory, 17 (5), 502-510.
Kindt, M., Soeter, M., & Vervliet, B. (2009). Beyond Extinction: Erasing Human Fear Responses
and Preventing the Return of Fear. Nature Neuroscience, 12, 256-258
Lee, S. H. et al. (2008). Synaptic Protein Degradation Underlies Destabilization of Retrieved
Fear Memory. Science, 319, 1253-1256.
Monfils, M. H., Cowansage, K. K., Klann, E. & LeDoux, J. E. (2009). Extinction-Reconsolidation
Boundaries: Key to Persistent Attenuation of Fear Memories. Science, 324, 951-955.
Pizzorusso, T. (2009). Erasing Fear Memories. Science, 325, 1214-1215.