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Responding to Violence, Suicide, Psychosis and Trauma

How Brain Remembers Single Events

ScienceDaily (Mar. 18, 2009) — Single events account for many of our most vivid memories – a marriage proposal, a wedding toast, a baby’s birth. Until a recent UC Irvine discovery, however, scientists knew little about what happens inside the brain that allows you to remember such events.


In a study with rats, neuroscientist John Guzowski and colleagues found that a single brief experience was as effective at activating neurons and genes associated with memory as more repetitive activities.

Knowing how the brain remembers one-time events can help scientists design better therapies for diseases such as Alzheimer’s in which the ability to form such memories is impaired.

“Most experiences in life are encounters defined by places, people, things and times. They are specific, and they happen once,” says Guzowski, UCI neurobiology and behavior assistant professor. “This type of memory is what makes each person unique.”

It is well known that a brain structure called the hippocampus is critical to memory and learning, but many questions exist about how brief experiences trigger the physical changes necessary for memory. In his study, Guzowski set out to learn how neurons in the hippocampus react to single events – particularly in the CA3 region, which is thought to be most critical for single-event memory.

Guzowski and postdoctoral researcher Teiko Miyashita put groups of rats on a rectangular track. Some rats took one lap; others did multiple laps. Inspecting the brains of rats that took one lap, they found that 10-15 percent of neurons in the CA3 region activated. The same percentage of CA3 neurons fired in the brains of rats that walked multiple laps.

Though previous computer simulations predicted that brief and repetitive experiences would activate CA3 neurons similarly, this is the first study to actually show that is the case.

Miyashita and Guzowski arrived at the percentages by examining the activation of a gene called “Arc” within hippocampal neurons. Past studies have shown that turning on Arc is required to convert experience into long-term memory.

“Together with our past findings, this study provides key insight into how fleeting experiences can be captured by the brain to form lasting memories,” Guzowski says.

Arc activation is disrupted in mouse models of mental retardation and Alzheimer’s disease.

“Our findings on Arc regulation in CA3 neurons should prove useful to researchers testing new therapies for Alzheimer’s disease,” Guzowski says. “If you understand how the hippocampus works, it is much easier to understand and potentially treat diseases that affect memory.”

UCI researchers Stepan Kubik, Nahideh Haghighi and Oswald Steward also worked on this study, published in The Journal of Neuroscience. The National Institutes of Health supported this research.


Adapted from materials provided by University of California – Irvine.
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New Strategy To Weaken Traumatic Memories

ScienceDaily (Mar. 17, 2009) — Imagine that you have been in combat and that you have watched your closest friend die in front of you.  The memory of that event may stay with you, troubling you for the rest of your life.  Posttraumatic stress disorder (PTSD) is among the most common and disabling psychiatric casualties of combat and other extremely stressful situations. People suffering from PTSD often suffer from vivid intrusive memories of their traumas.

Current medications are often ineffective in controlling these symptoms and so novel treatments are needed urgently.  In the February 1st issue of Biological Psychiatry, published by Elsevier, a group of basic scientists shed new light on the biology of stress effects upon memory formation.  In so doing, they suggest new approaches to the treatment of the distress related to traumatic memories.  Their work is based on the study of a drug, RU38486, that blocks the effects of the stress hormone cortisol.

Using an animal model of traumatic memory, investigators at the Mount Sinai School of Medicine show that treatment with RU38486 selectively reduces stress-related memories, leaving other memories unchanged.  They also found that the effectiveness of the treatment is a function of the intensity of the initial “trauma.”  Although this particular study was performed in rats, their findings help to set the stage for trials in humans.

Cristina Alberini, Ph.D., corresponding author on this article, explains how their findings will translate into developing clinical parameters: “First, the drug should be administered shortly before or after recalling the memory of the traumatic event. Second, one or two treatments are sufficient to maximally disrupt the memory. Third, the effect is long lasting and selective for the recalled memory. Finally, the time elapsing between the traumatic experience and the treatment seems to be an important parameter for obtaining the most efficacious treatment.”

Dr. John Krystal, Editor of Biological Psychiatry and affiliated with both Yale University School of Medicine and the VA Connecticut Healthcare System, discusses the significance of the findings: “When treating PTSD, clinicians often attempt to reduce the negative distortions of traumatic memories so that people can better cope with their traumas.  The new study by Taubenfeld and colleagues suggests that blocking the effects of cortisol may be one strategy to promote the ‘normalization’ of traumatic memories.”  Dr. Alberini agrees, noting that “these results suggest that carefully designed combinations of behavioral and pharmacological therapies may represent novel, effective treatments for PTSD or other anxiety disorders.”


Adapted from materials provided by Elsevier, via AlphaGalileo

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Differences In Recovered Memories Of Childhood Sexual Abuse

ScienceDaily (Feb. 4, 2009)
When a child experiences a traumatic event, such as sexual abuse, it may not be until well into adulthood that they remember the incident. It is not known how adults are able to retrieve long-forgotten memories of abuse and there has been some controversy as to the authenticity of these reports.

The results of a new study in Psychological Science, a journal of the Association for Psychological Science, suggests that there are important differences between people who gradually recover memories of abuse during suggestive therapy sessions and those who recover memories of abuse more spontaneously. Psychologist Elke Geraerts of the University of St. Andrews and her colleagues reveal that these people are either susceptible to recovering false memories or have a tendency to forget earlier recollections of the abuse.

The study volunteers included 120 women who were classified into four groups, based on their responses during a preliminary interview. The groups were: women who spontaneously recovered memories of childhood sexual abuse on their own, women who gradually recovered memories of childhood sexual abuse during suggestive therapy sessions, women who had never forgotten having been sexually abused and women who had never been sexually abused. All of these women participated in a false-memory test.

They studied a list of related words (such as bed, rest, awake and tired). After a few minutes, they were shown a set of words (which included ones they had studied as well as new words) and had to indicate which words were on the original list.

The results showed that the women who recovered their memories of childhood sexual abuse during suggestive therapy were the most prone to false memories. For instance, women from this group were more likely to select sleep (in the example above) as having been on the original list, when in fact, it was not.

The women then participated in another memory test, which measured the participants’ propensity to forget what they had just remembered. The results of this test revealed that the group who spontaneously recovered memories of childhood sexual abuse was the most likely to forget that they had successfully remembered certain words earlier.

The authors note that their findings argue against the generalization that all recovered memories of childhood sexual abuse are based on false recollections and “that such effects appear to be associated with suggestive therapy, not recovery of childhood sexual abuse in general.” They conclude that this research has important implications for clinicians who treat patients reporting recovered memories of childhood sexual abuse.

The authors suggest that these clinicians should consider the context of the recovered memories to most effectively treat their patients.
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Adapted from materials provided by Association for Psychological Science.

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‘Speed Of Thought’ Guides Brain’s Memory Consolidation

This could be important in understanding the processing of traumatic mmemories

ScienceDaily (Nov. 16, 2007) — Scientists at The University of Arizona have added another piece of the puzzle of how the brain processes memory.

Bruce McNaughton, a professor of psychology and physiology, and his colleague David Euston have shown that, during sleep, the reactivated memories of real-time experiences are processed within the brain at a higher rate of speed. That rate can be as much as six or seven times faster, and what McNaughton calls “thought speed.”

Memory stores patterns of activity in modular form in the brain’s cortex. Different modules in the cortex process different kinds of information – sounds, sights, tastes, smells, etc. The cortex sends these networks of activity to a region called the hippocampus. The hippocampus then creates and assigns a tag, a kind of temporary bar code, that is unique to every memory and sends that signal back to the cortex.

Each module in the cortex uses the tag to retrieve its own part of the activity. A memory of having lunch, for example, would involve a number of modules, each of which might record where the diner sat, what was served, the noise level in the restaurant or the financial transaction to pay for the meal.

But while an actual dining experience might have taken up an hour of actual time, replaying the memory of it would only take 8 to 10 minutes. The reason, McNaughton said, is that the speed of the consolidation process isn’t constrained by the real world physical laws that regulate activity in time and space.

The brain uses this biological trick because there is no way for all of its neurons to connect with and interact with every other neuron. It is still an expensive task for the hippocampus to make all of those connections. The retrieval tags the hippocampus generates are only temporary until the cortex can carry a given memory on its own.

“It’s a slow process,” said McNaughton.

“The initial creation of the tag is made through existing connections. In order to do the rewiring necessary to have the intermodular connections carry the burden takes time. What you have to do is reinstate those memories multiple times. Every time you reinstate the memory, the modules make a little shift in the connection . . . something grows this way, grows that way, a connection gets made here, gets broken there. And eventually, after you do this multiple times, then an optimal set of connections gets constructed,” Mc Naughton said.

The brain is generally thought to do all of this during sleep, specifically slow-wave sleep, when the brain is not busy with processing real-time inputs. McNaughton has developed the technology to record from multiple probes, each of which can track the activity of a dozen or more brain cells.

“We need groups of cells because in order to identify a pattern, you have to look at the collected activity of many neurons,” McNaughton said. His previous research has show that cells that fired during activity prior to sleep, also fired in the same sequential patterns during sleep. During sleep, the hippocampus sends little, 100-millisecond bursts of activity to the cortex as much as three times per second.

What remains is finding an experiment that will enable researchers to demonstrate that changes in the memory reactivation process would affect memory consolidation but not damage the brain in the process.

“The more practical point, I think, is that this methodology, the ability to measure how fast the brain is processing at the level of changing the state of the brain from one 10- millisecond epoch to the next, how fast the internal state is sweeping through its memories or its allowable patterns is, I think, a model for thought speed,” McNaughton said.

Knowing the determinants for the speed of thought, he said, might allow studies of the effects of drugs, developmental anomalies and the behavioral therapies that might improve them.

Adapted from materials provided by University of Arizona.

 University of Arizona (2007, November 16). ‘Speed Of Thought’ Guides Brain’s Memory Consolidation. ScienceDaily. Retrieved November 17, 2007, from http://www.sciencedaily.com­ /releases/2007/11/071115164450.htm

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