One of the most universal experiences is that of stress, whether it’s because you’re cramming for an exam, or because you’re simply worried about what you’re going to eat for dinner. Most of the time we label stress as overwhelmingly negative because of the jittery feelings that follow it, but a recently conducted study by Anne Bierbraur and her colleagues found that experiencing it actually increases our memory of situations.
In the study, the researchers focused on neural representation in two parts of the brain; the hippocampus and the amygdala. The hippocampus was studied because it plays a role in supporting distinct and bound representations of episodic memory (the subject of study). The amygdala was used as well because of the previous research that indicated that the amygdala represents not only fear memories but also the subjective valence of odors. The researchers used Representational Similarity Analysis (RSA) to investigate the structure of neural representations in these areas of the brain. To produce measurable neural representations, the Trier Social Stress Test (TSST) was employed based on its previous success in inducing psychosocial stress. This test involves inducing stress by requiring participants to complete an interview-style presentation to a committee of two people that were acting in a neutral or reserved manner. The results that this group produced would then be contrasted with the experimental group, a group of individuals that underwent a friendly TSST (f-TSST), which entailed a similar interview-style presentation but with an encouraging committee that allowed them to freely talk about career aspirations and hobbies. In both groups, the participants encountered 24 objects with committee members utilizing half of these objects. The day after the interview the individuals were brought back to the lab where they were subjected to fMRI scans to assess the neural representations of the object and of the stressors in an individual’s episodic memory. To do this the participants took a recognition memory test and did fMRI recordings where they were presented with pictures of the 24 objects they encountered during their sessions as well as 24 distractors that presented images of objects similar to the objects to encounter as well as easier distractors that did not resemble the objects that were in the interview. This same idea was repeated on the faces of the committee members. Because there were two groups there were required controls that the experimenters had to take into account for example the groups did not differ in age, trait anxiety, self-esteem, depression score, wake-up and testing time on day 1, and baseline scores of effect and cortisol on day 1.
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The three things that were measured in memory performance were the number of freely recalled objects, recognition, memory for these objects, and spatial memory of object positions in the f-TSST. The results in these categories were similar, there was a higher performance for central versus peripheral objects and for TSST versus f-TSST participants, indicating that stress improved memory performance, but the effect was more pronounced for central objects, which replicated previous results. The experiment also found that episodic binding was higher for central objects in the left amygdala, this was found by calculating the difference in similarities between objects from the episode and distractors versus the difference in similarities among objects that were part of the episode. This representation of central objects is generalized in the left amygdala because stress selectively moved the neural representations of central objects closer together in representation and not further apart.
So, why do we remember the central aspects of a stressful episode well? The experiment shows that stress integrates central objects from an episode and binds them to the main stressor thereby aligning with concepts of “emotional binding,” (this suggests that the amygdala integrates items and emotions with emotional episodes thereby producing memory traces with highly memorable representational structure). So maybe stress is more positive than we would like to believe.
Toucan Play That Game 
This is so interesting! I’m really curious as to how self-esteem is measured and how their depression score was calculated.
This is an interesting take on stress, yet one I find seems to be true. Stressing before a test sometimes oftentimes helps me to remember the material better if I channel it in the right way.
This made me realize that sometimes stress does help. When I’m stressing over a test in class i sometimes just remember the material again.