By Karl Andrei Luarez

PHOTO: News Hub

Do you ever wonder why stressful events, such as a difficult test, tend to stick in your mind more clearly than neutral ones, such as a stroll through the park?

As the brain stores information on items present in a specific event, it develops a distinct pattern of activity for such episodes called memory traces. Stress has the ability to alter such patterns which could lead to improved memory.

In the journal Current Biology, a team of researchers led by Anne Bierbrauer, Professor Oliver Wolf, and Professor Nikolai Axmacher of the Ruhr University Bochum Institute of Neuroscience recently published a study that suggests the reason why.

The team used a Trier Social Stress Test (TSST) which required a simulated job interview for two separate groups of participants. 

The first group was put through a stressful process in which they received only neutral feedback and no encouraging words from the interview committee members. The participants were negatively impacted showing significant stress response. The other group was in a more relaxed and non-stressful environment where the committee would react positively towards them.

During the interview, the participants were presented with everyday items like a cup of coffee, labeling them as peripheral objects. The interviewers used half of the items, either by taking a sip from the cup or just simply holding them, thereby making them central objects.

On the following day, the team showed participants similar images of objects present during the interview as they scanned their brains using functional magnetic resonance imaging (fMRI) to evaluate the neural effects of the objects and the stressors.

They found that participants who underwent a stressful experience showed great recognition and recall of central objects. The brain also showed similar reactions to central objects compared to the face of committee members, the stress triggers. 

“It seems that the link between the objects and the stress triggers was crucial for the enhanced memory,” said Professor Axmacher, one of the authors.

The study pointed out that stress hormones like noradrenaline and glucocorticoids may have a significant influence on memory formation on stressful effects. Because of this, they concentrated their attention on the effects stress hormones have on the amygdala and hippocampus, two areas of the brain that are important for responding to stress stimuli and memory formation, respectively.

According to the findings, there is increased cellular activity in the left amygdala, which suggests that episodic memory is better in central objects of a stressful event in the region because it strengthens generalized representations of central objects when exposed to stress.

"It's more important for people, for survival, to see the lion in the bush than it is to notice the lovely flower that's blossoming on the opposite side of the road," says Laura Carstensen, a psychology professor at Stanford University. The way humans evolved, she believed, was to protect themselves from potentially life-threatening situations in the future.

The authors feel that their findings will help address major predictions from famous theories on emotional and stressful memories, as well as provide a unique paradigm for future research into the psychopathology of memory.