According to a study by researchers at University College London (UCL), when a person experiences a traumatic event, accompanied by very intense memories about that specific negative event, but interestingly it maintains a much vague memory of the surrounding context. This occurs because the amygdala - the part of the brain that is used to store emotional memories - becomes much more active during a negative event, while areas that store neutral content substantially reduce its activity.
Dr. James Bisby (UCL Institute of Cognitive Neuroscience) explains that: "When we present people with negative content along with neutral content, the areas of the brain involved in the storage of negative content become more active, while those involved in storage the surrounding context becomes less active. ”
And when we experience a new event, not only we store the event content in memory, such as the people we met, but also formed associations with the context in which the event occurred. The hippocampus is a crucial brain region for the formation of these associations, so that all aspects of the event are placed in the appropriate context, and it is here that one can observe how the activity in these cases is diminished.
This study, published in the journal Social, Cognitive, and Affective Neuroscience, has important implications for the understanding of the conditions derived from negative events, such as the Post-traumatic Stress Disorder (PTSD).
"The imbalance between the memory of the event and the associative memory could lead to an intense memory, but fragmented by the traumatic content of what happened, without the correct surrounding information that would put it in the appropriate context," adds the lead author, the professor Neil Burgess, director of the UCL Institute of Cognitive Neuroscience.
"People who have suffered a traumatic event may experience vivid and distressing intrusive images. of it, as in Post-traumatic Stress Disorder. These intrusive images could occur due to memory reinforced by the negative aspects of the trauma, but they are not entirely linked to the context in which it occurred. This may be the mechanism behind the 'flashback', where we involuntarily reexperience traumatic memories as if they were happening in the present. "
During the study, 20 participants were placed in a Magnetic Resonance Scanner and several images were shown to remember. Some of these photos showed traumatic content, such as seriously injured people.
The results showed that the participants remembered the negative images better compared to the neutral ones. This was reflected in increased activity in the amygdala, a part of the brain used for the processing of emotional information. It also took much longer to remember what other images appeared next to the negative ones, reflecting less activity in the hippocampus.