Mechanisms of Post-Traumatic Emotional Stress Iden
> 5/12/2008 1:19:56 PM

Severe emotional traumas fortunately do not fit within the fairly comfortable framework of our everyday lives, and that jarring irregularity is one of the reasons they often prove so hard to shake. The shock of an extreme event throttles our emotions to the point that its effects will stick out in our minds for some time no matter how hard we try to forget. Just as we usually retain clear memories of such significant events as a marriage or the birth of a child, so too will we often remember the most horribly traumatic events in life, be they injuries, accidents, experiences in battle or personal loss. In fact, negative memories often remain clear in our minds for the longest period of time due to that very irregularity. The PTSD phenomenon centers around the fact that these firmly-established memories can change nearly every aspect of our behavior, affecting us in some way even when we're not actually thinking about them. Experts have long wondered which combined elements of our brain chemistry reinforce that unfortunate pattern. Swiss researchers, with the help of some genetically modified mice, seem to have come closer to understanding the neurological equation than ever before.  

In the most recent related study, scientists at the University of Zurich fed a population of lab mice with a sugar solution containing elements that induced severe nausea. The mice understandably avoided this solution for some time afterward, but researchers were able to activate a cause-effect chain linking synaptic brain chemistry to processes within the cell nucleus itself in order to curb the mouse population's extreme aversion to the solution. The process was designed to minimize their negative impressions of the substance to the point that they would feel free to consume it again, and it could only be acheived over time due to the power of the preceding physical and emotional trauma.

The experiment centered around the memory-inhibiting enzyme calcineurin, the deactivation of which can help to ensure the clarity and permanence of certain memories. Researchers now believe that they can use it to gradually guide individuals away from the specific memories that plague them. Increased activity of this substance inhibits the body's ability to retain the memory of various events. The suppression of calcineurin alternately increases the presence of a gene regulator called Zif268 in the brain's emotional center, the amygdala. This regulator controls a large share of the genes responsible for the formation of memory. The yin-yang relationship between these two genes can, when controlled by exeperimental labratory tweaking, power the process of minimizing traumatic memories and allowing them to be replaced with more positive recollections. By the time the mice in question overcame their initally negative impressions of the solution and began to consume it again, it had been rendered nausea-free. The negative memory cycle had been effectively reversed.

Researchers stress the ability of this study to highlight the differences between factual and emotional data: while information can truly disappear from one's memory banks, particularly if cognitive functions are compromised by injury, disease or dementia, the memory of traumatic events simply loses relevance or poignancy, moving down an internal list of most painful memories with the passage of time. In severe cases of PTSD, the most horrific memories never leave, damaging a person's ability to live in very fundamental ways. Intervention and medication are often the only ways to counteract this condition, and the process is long and difficult at best. Researchers unfortunately do not foresee a real-world application for their work in the near future because the methods they used require some form of genetic modification or tweaking. But while standard ethics prevent us from inducing transgenesis in humans, other researchers can hopefully use this information to help them design more effective medications or less invasive behavioral treatments. An increased familiarity with the processes behind PTSD and related states of trauma is a step forward.

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