Trials, strokes of fate or other stressful situations – even years later, people often have amazingly detailed pictures of such experiences before their eyes. An experimental study now sheds light on the neural mechanisms underlying this acute memory. The researchers were able to illustrate that objects that are felt under stress are stored in an interconnected brain and that their processing is based on activity similar to that of stress triggered memories.
Pattern of relationships, color of cups, faces of people involved: People can often recall scenes and impressions regarding stressful experiences such as exam situations in astonishing detail over long periods of time. On the other hand, it’s easy to forget the impressions of a walk in the park on the same day. What is this difference about? Researchers at Ruhr University Bochum are investigating the background of this memory phenomenon. As they point out, in addition to providing fundamental insight into how the brain works, this research could also provide an understanding of the psychological disorders associated with problematic – traumatic – memories.
stress memories in sight
Basically, it is already known that the increased release of certain neurotransmitters in the brain plays a role in the enhancement of memory performance in stressful situations. These messenger substances apparently cause changes in neuronal representations during these experiences. Previous studies and theoretical considerations have so far offered different explanations for how memories of stressful experiences differ from those of neutral ones. To gain more insight, Bochum scientists have now recorded memory traces in relation to actual stressful situations through a study with a total of 65 volunteers.
To ensure experimental stress, the so-called Trier Social Stress Test was used: in a hypothetical job interview, test subjects had to respond to two people who appeared to be sedentary and gave no positive response. In addition, he was filmed demonstratively in the situation. Subsequent saliva tests showed that it did indeed cause stress in the test subjects. During the unpleasant situation, a total of 26 objects could be seen in the room: from garbage cans to coke cans to fans. The “committee” used some “central objects”: for example, some vessels were used to carry certain drinks. In the control group, test subjects were confronted with similar objects and tasks, but not exposed to any stressors: it was a friendly conversation without video recording.
Special features of stress become apparent
One day after the test, the researchers showed study participants in both groups the objects they had seen while they recorded their brain activity in a magnetic resonance tomograph. The focus was on the amygdala – a brain region important for emotional learning, among other things. Comparison of neural traces revealed: in the control group, neural patterns hardly differed from non-central objects in the room in terms of objects used in the relaxed interaction condition. In test subjects experiencing stress, however, memory traces between used objects and not used objects differed significantly: those objects that were the focus of the stressful episode because they were manipulated by the experimenters were found in the amygdala. had equal representation. This means: The neural anchoring of important objects from stressful situations appears grouped and clearly separated from other impressions, the scientists explain.
In addition to photographs of objects from the application position, they also showed pictures of test subjects to people on the application committee the day after the stress test. As the scientists point out, from a psychological point of view, they were not some sort of object in the context of the situation, but rather a stress trigger. A comparison of the ability to remember and brain activity when viewing the faces of different objects showed that the test subjects specifically remembered objects whose brain activity was similar to that triggered by the committee members’ memory. “It therefore appears that the association between objects and the stress trigger was conclusive for improved memory,” explains co-author Nikolai Axmacher.
As the researchers conclude, the results of their study now suggest: the mechanisms underlying the strengthening of emotional memories are characterized by the fact that important aspects of a related landscape are interconnected at the neural level and then triggered by stress. are associated with. “This result may be an important building block for a better understanding of emotional and traumatic memories,” says first author Anne Birbrauer.
Source: Ruhr University Bochum, expert article: Current Biology, doi: 10.1016/j.cub.2021.09.044
