Why do we remember stressful experiences better?

Date:
October 15, 2021
Source:
Ruhr-University Bochum
Summary:
When the brain stores memories of objects, it creates
a characteristic pattern of activity for each of them. Stress
changes such memory traces.



FULL STORY ========================================================================== Stressful experiences are usually remembered more easily than neutral experiences. Researchers at Ruhr-Universita"t Bochum (RUB) have analysed
the reasons why this is the case. They put people in stressful situations during simulated job interviews and then recorded their memory of objects
from these interviews. Using functional magnetic resonance imaging,
they analysed brain activity while the participants saw the objects
again. Memories of objects from stressful situations seem to rely on
similar brain activity as memories of the stress trigger itself.


==========================================================================
The team headed by Anne Bierbrauer, Professor Oliver Wolf and Professor
Nikolai Axmacher from the RUB Institute of Cognitive Neuroscience
describes the findings in the journal Current Biology, published online
on 14 October 2021.

Different theories "We usually have detailed images in your mind's eye
of stressful experiences, such as taking the driving test, even after
many years," says Oliver Wolf.

"Whereas a walk through the park on the same day is quickly
forgotten." The neuroscientists at RUB would like to understand the
reasons for this phenomenon.

Earlier studies and theoretical considerations had led to different
predictions about how memories of stressful experiences differ from
neutral ones: "One idea was that very different memory representations
might have been the key to more powerful memories; on the other hand,
there were indications that stress memories have resembled each other
more closely," explains Anne Bierbrauer. The current study provides
evidence for the second theory.

Analysing stressful experiences in the lab Unlike in many laboratory
studies, the researchers set out to record the memory trace of a real
event in their experiments, using the so-called Trier Social Stress Test
for this purpose. This test requires the participants to speak in front
of an application committee, all of whom wear a neutral expression and
don't give any positive feedback. The test unfailingly triggers stress
in the participants.

During the job interview simulation, the committee used a number of
everyday objects; for example, one of the committee members took a sip
from a coffee cup. The control group was confronted with the same objects,
but the participants were not subjected to any stress. One day later,
the researchers showed the objects to participants in both groups while recording brain activity in a magnetic resonance imaging scanner. The
stressed participants remembered the objects better than members of the
control group.

The researchers analysed primarily the brain activity in the amygdala,
a region whose main functions include emotional learning. They compared
the neuronal traces of objects that had been used by the committee
members in the stress situation with those of objects that hadn't been
used. The result was: the memory traces of objects that had been used
resembled each other more closely than those of objects that hadn't
been used. This was not the case in the control group. In other words,
the brain representations of the objects from the stressful situations
were very closely linked, and they were thus clearly set apart from
other experiences.

Stressful memories are based on their resemblance to the stressor One
day after the stress test, the researchers showed the participants not
only pictures of the objects from the job interview, but also photos of
members of the committee. The participants mainly remembered objects
where the brain activity was similar to the activity triggered by the presentation of the committee members. "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," concludes Nikolai Axmacher.

The findings obtained in this study argue against the theory that stronger memories are triggered by memory representations that differ from each
other as much as possible -- at least when it comes to emotional or
stressful memories.

Rather, the mechanism that reinforces emotional memories appears to
be rooted in the fact that the important aspects of the episode are
linked at the neural level and become more closely related to the stress trigger. "This result could be an important building block to better
understand emotional and traumatic memories," points out Anne Bierbrauer.

========================================================================== Story Source: Materials provided by Ruhr-University_Bochum. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. Anne Bierbrauer, Marie-Christin Fellner, Rebekka Heinen, Oliver
T. Wolf,
Nikolai Axmacher. The memory trace of a stressful episode. Current
Biology, 2021 DOI: 10.1016/j.cub.2021.09.044 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2021/10/211015184209.htm

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