Can Painful Memories Be Erased? A HealthCentral Explainer

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    Everyone has a few memories they’d like to forget, whether it’s the loss of a loved one or a past traumatic event.  No matter what the memory, it becomes part of who you are, and has the potential to influence the decisions you make.


    But what if we could alter bad memories or even erase them altogether?  There have been some breakthrough studies in the past year that suggest that’s possible.


    How are memories made?


    Before problems such as memory loss and post-traumatic stress disorder can be addressed, scientists needed to understand how memories become encoded in the brain.  Memory encoding is a biological phenomenon connected with all our senses.  As an event unfolds, for instance, the brain takes note of a person’s physical features, the sound of their voice, maybe the touch of their hand.  These perceptions combine to form a cohesive experience.  To create a proper memory, however, you must first be paying attention, which is why so many of our routine experiences aren’t firmly committed to memory, say, your commute to work. Scientists aren’t sure whether the brain stores information at the input stage or only after the brain identifies the stimuli as important, but we do know that how much one pays attention determines how the memory is remembered. 

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    What is the difference between short and long term memory?


    Once an experience is stored in the brain, it is categorized into one of three categories: sensory stage, short-term memory, and long-term memory.  These categories help the brain organize memories by their importance.  Short-term memory is treated as a lower priority and has a very limited capacity; usually seven items for about 20 or 30 seconds at a time, but there are mental exercises that can be done to help increase this capacity.  Gradually, some short-term memories rise to become long-term memories.  In order for this to happen, the short-term memory must go through a process known as consolidation.  During consolidation, the memory is recalled repeatedly and that eventually triggers chemical and physical changes in the brain which permanently encode the recollection for long-term access.   (Sadly, this is why cramming before a test doesn’t help much.) In general when we think of memory, we are referring to long-term memories that have had a lasting impression in our lives. But before reaching that status, all memories must cycle through the sensory and short-term memory phases.


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    How can emotional memories be erased?


    According to new research from Uppsala University, if a traumatic memory is recently formed, it may be possible to prevent it from becoming a long-term memory.  During consolidation, a memory is malleable for a small time before it becomes a permanent long-term memory.  Researchers now believe that during this period of malleability, fearful memories can be substantially modified into neutral memories.  


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    How was the study conducted?


    Study participants were shown a picture while given an electric shock so that the sight of the picture would elicit fear.  In that way, a painful memory was introduced.  They were brought back a day later and reminded of the fearful incident, inducing the reconsolidation process.


    Then the participants were divided into two groups.  The first received “extinction treatment” for 10 minutes following reconsolidation--they were shown the same images over and over, without shocks, so they would stop associating them with pain.  The second group received this same treatment, but, instead, after a six-hour delay after reconsolidation.  The researchers then used an MRI scanner to measure the impact of the fear memory.  Lastly, on the third day of experimentation, researchers examined the amygdala region of the participants’ brain--where fearful memories are stored-- to analyze the role it plays in erasing trauma. 



    What were the findings?


    Following the extinction treatment, the first group showed no fear at all, while the second group still showed a significant amount of fear, confirming that timing of the treatment matters.  The pain associated with the memory could only be neutralized shortly after the memory was recalled.  The amygdala analysis showed that even on a third day, the first group showed no brain activity indicating fear, while the second group showed activity in the amygdala, indicating a persistent fear. 


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    What do these findings mean?


    These findings provide new hope for those at risk of developing post-traumatic stress disorder or for those who are prone to suffering from negative memories.  For instance, soldiers in combat would need to be treated soon after a traumatic experience so the fresh memory can be altered. 


    With more time and research, these methods could be developed to the point that medication for traumatic memories is no longer necessary.  This recent study is significant because it represents a first step in treating painful memories using behavioral intervention rather than medication. That would prevent risks associated with conventional drug treatments.  Previous studies had focused on inhibiting cortisol, using beta-blockers, and using metyraprone to decrease cortisol (stress) levels. 



    T. Agren, J. Engman, A. Frick, J. Bjorkstrand, E.-M. Larsson, T. Furmark, M. Fredrikson. Science September 2012 DOI: 10.1126/science.1223006


    n.p. (2012, September 22). "Emotional Memories Can Be Erased From Our Brains." Medical News Today. Retrieved from

  Contributors.  "What exactly is amnesia?"  01 August 2011. <> 26 September 2012.


Published On: September 28, 2012