September 21, 2012
Fearful Memories Can Be Permanently Erased
redOrbit Staff & Wire Reports - Your Universe Online
Emotional memories can be erased shortly after they are formed through behavioral intervention alone, without the aid of medications, according to a new study published Thursday in the journal Science.The breakthrough offers a major step forward in understanding where fearful memories are processed in the brain, and how to permanently erase them. The research could be particularly helpful for people suffering from conditions such as anxiety and post-traumatic stress disorder, the researchers said.
When a person learns something, a lasting long-term memory is created through a process of consolidation, which is based on the formation of proteins. When we remember something, the memory becomes unstable for a short time, and is then restabilized by another consolidation process. In other words, we are not remembering what originally happened, but rather what we remembered the last time we thought about what happened.
The study´s researchers sought to examine whether disrupting the reconsolidation process that follows upon remembering something could affect the content of memory.
They showed a small group of study participants a neutral picture while simultaneously administering an electric shock so that the picture came to elicit fear, triggering the formation of a fear memory.
The same picture was then shown to the participants the following day, but without an accompanying shock, in order to activate this fear memory (the beginning of the reconsolidation process).
Although seeing the picture again reactivated the original fear memory, it also, theoretically, made the memory easier to erase.
The researchers then divided the subjects into two groups. The first subgroup was repeatedly shown the picture, without the shocks, in order to disrupt their reconsolidation process so they would stop associating one with the other.
The second group received the same treatment, but only after a six-hour delay -- enough time to allow their reconsolidation process to complete.
The researchers then measured how "present" the fear memory was in the participants of both groups by measuring their skin conductance.
The first group, who had their reconsolidation process disrupted, showed no fear, while the second group showed substantial fear, confirming that the timing did indeed make a difference. In other words, extinguishing the bad memory only worked when it was done shortly after the memory was reactivated.
The researchers used an MR-scanner to show that traces of the bad memory had also disappeared from the part of the brain that normally stores fearful memories -- the nuclear group of amygdala in the temporal lobe.
“These findings may be a breakthrough in research on memory and fear,” said lead author Thomas Ã gren, a doctoral candidate at the Department of Psychology at Uppsala University.
“Ultimately the new findings may lead to improved treatment methods for the millions of people in the world who suffer from anxiety issues like phobias, post-traumatic stress, and panic attacks.”