Stressful experiences are more often recalled than neutral experiences. Ruhr-Universitat Bochum (RUB), researchers have examined the reasons for this phenomenon. The researchers put participants in stressful situations and recorded their memories of objects from the interviews. Functional magnetic resonance imaging was used to analyze brain activity as participants saw the objects once more. Memory of objects in stressful situations seems to be based on the same brain activity as memories about the stress trigger.
Anne Bierbrauer, Professor Oliver Wolf, and Professor Nikolai Axmacher, all from the RUB Institute for Cognitive Neuroscience, presented their findings in Current Biology.
Other theories
Oliver Wolf says, “We usually have detailed images in your mind’s eye of stressful experiences, such as taking the driving test, even after many years. Whereas a walk through the park on the same day is quickly forgotten.” RUB neuroscientists would love to explain this phenomenon.
Previous studies and theories had produced different conclusions about the differences between memories of stressful experiences and neutral memories. Anne Bierbrauer says that one theory suggested that memory representations could be very different. On the other, there was evidence that stress memories might have resembled each others more closely. This second theory is supported by the current study.
Analysis of stressful experiences in the laboratory
The researchers used the Trier Social Stress Test to record the memories of an actual event, which is something that is not possible in laboratory studies. Participants must speak before a panel of applicants. They are required to wear neutral expressions and give no feedback. Participants are often stressed by the test.
During the job interview simulation, members of the committee were faced with a variety of everyday objects. One member of the committee took a cup of coffee from a cup. The same objects were presented to the control group, but participants were not exposed to stress. The researchers then showed the objects to both groups and recorded brain activity using a magnetic resonance imaging scanner. Participants in the stressed group remembered the objects better that those in the control group.
The brain activity of the amygdala was the focus of the researchers’ analysis. This region is responsible for emotional learning. The researchers compared neuronal traces of objects used in stressful situations by members of the committee with those that were not. It was found that objects with memory traces that had been used were more similar to each other than objects without. In contrast, this was not true in the control group. This means that the brain representations for the objects in stressful situations were clearly distinct from other experiences.
The basis of stress memories is their similarity to the stressor
The researchers showed participants photos of the objects they had seen at the interview and also pictures of the members of the committee one day later. Participants recalled objects whose brain activity was similar to that triggered by the presentation from the members of the committee. Nikolai Axmacher concludes “The committee members triggered the stress in the interview situation. Accordingly, it seems that the link between the objects and the stress triggers was crucial for the enhanced memory.”
These findings support the idea that memories that are as different as possible from one another can trigger stronger memories. However, this is not true for emotional memories. The mechanism that reinforces emotional memories seems to be in the neural linkage of important episodes and their closer relationship to stress triggers. Anne Bierbrauer says that this result could help us better understand emotional and trauma memories.
Source: https://www.ruhr-uni-bochum.de/en