The ultimate true prevalence of psychiatric disorders across
the globe remains to be a topic that isn’t to this day fully understood to the
same level as other health conditions. The realm of psychiatric health disorders
is viewed as a separate and what we know today regarding such topics are not
fully representative of their associations to the body themselves. In other words,
there is a more complex interconnection between the methods that approach the
studies of human health conditions and the insights and what researchers
already know about psychiatric disorders. Although extensive research hasn’t
been conducted to study all the relationships and how to ultimately alter such
disorders to be of benefit to individuals, there has been some remarkable beginning
findings. One such study done by Grella et al. examine the stability and flexibility
of memories and specifically studied how neuro modulators and dysregulation of systems
can lead to maladaptive cognitive and behavioral states. She touches base on
how negative memory changes can occur for individuals with PTSD. Many people
may have the question as to what the voluntary retrieval aspect of emotional
experiences for PTSD are as PTSD seems to rely heavily on involuntary retrieval
aspects. In other words, one might ask themselves how exactly do these changes
in memory relate to the voluntary aspect as one would assume that it is all involuntary
and that is why PTSD happens in the first place. This was further researched in
a study done by Steinmetz et al. in which it was studied what the different
effects PTSD had on memory for emotional information in specific that in not in
any way related to trauma. So, both these studies, further develop way in which
to understand how memory is impacted significantly in terms of PTSD and its
limitations as to what it doesn’t change to use it in ways that can ultimately
help individuals who are experiencing these psychiatric disorders. There is
much research to still be done regarding all of this, as it is hard to tell the
full impact of what little findings we have to impact these patients
dramatically. However, there is some different types of research that has been
done that give insight to this information that can lead to further directions
with future studies to advance further in these topics.
In a recent
study, “The stability and flexibility of memory traces in psychiatric
disease-like states” Grella et al. had given a talk that discussed a bit of her
research that she has done. She started off by discussing how memory updating
serves an adaptive role at time in ensuring that the most relevant information
is accessible in memory and that ultimately tells us that memory is malleable. In
other words, memory is always in the work of construction, deconstruction, encoding,
or reconsolidation. She touches base on how the pathway that goes from the
locus coeruleus to the hippocampus may have a circuit that is important for memory
updating and remapping contextual representations. Grella et al. had used a
cellular compartmental analysis of temporal in situ hybridization (catfish)
to further study the phasic LC activation that drives memory updating. She goes
into detail about the phenomenon of being at two places at once that comes from
the hippocampus resetting in a way that makes them in a different place which
is mediated by norepinephrine. When the system has a high amount or an overactive
of the LC, that may lead to cognitive inflexibility but in certain cases where
dysregulation is involved, the high tonic signaling eventually reduces the signal
to noise ratio. She relates this specific finding to patients who have PTSD who
bring up old trauma related representations and memories but have this memory
updating impairment where their brain is not able to functionally remap to incorporate
safety signals into their life. She talked about the animal models of stress
which one of the most common is the foot shock that is used to study PTSD. Using
viral technology, more specifically the Tet Tag system where the mice get a
virus injection which allows for the cells to be transduced and for genetic
material to eventually enter the nucleus. This is because the tTa part of the
injection binds to the TRE. The researchers don’t want that binding to happen because
they want to tag only one specific memory the animal has experienced. So, an
inducible that is named DOX was put into their food and so only those specific
memories and those cells associated to them is activated. Now, the aim of one
of the experiments that Grella ran was to make negative memories less negative
by mediating positive memories which serves as a kind of artificially induced
recall. Additionally, they want to see would those effects last even during spontaneous
recovery of fear. Results showed that artificial reactivation of
hippocampal-mediated positive memories during fear memory reconsolidation does
in fact reduce fear enduringly. The conclusions of her study included that
hippocampal cells that were active during the encoding of a positive experience
are sufficient to interfere with the expression of a fear memory. In addition,
the effects seem to be specific to the memory undergoing reconsolidation and
appear to also be long-lasting. So, in these ways the original fear memory was
altered. These animals were expecting something bad to happen to them and in
this case was a foot shock. So, either a foot shock was given which ultimately
gave a zero-prediction error. Or, something that fell upon the valence where a
positive thing occurred that correlated with the magnitude of the positive
prediction error and the decrease freezing of the mice that were observed.
In the
research done by Grella et al., it only touched based on the memory changes
that occurred in patients with PTSD and didn’t really talk about and control
participants. This was incorporated in the study done by Steinmetz el al. in
which a trauma-exposed control group that didn’t have PTSD was involved so
there could be comparisons that could be made. The researchers in this study tried
to find the effect of PTSD on memory for emotional information that is not in
any way related to the trauma. PTSD is currently only defined by the cognitive
changes that take place in the involuntary memory following a traumatic
incident. We already know that there is not much of information about the
voluntary retrieval aspect of emotional experiences, and this is what the
researchers wanted to study more of. To do this, researchers had participants
that were separated into three different groups which consisted of participants
either currently having PTSD, experiencing trauma but did not have any current
diagnosis of PTSD, or had neither or. These individuals were then shown visual
scenes in which they included an item that was either positive, negative, or
neutral on a neutral background and then around forty-five minutes later, they
had to do a recognition memory test for the items and backgrounds separately. When
there seemed to be a big difference in the item and background memory for
emotional scenes, there seemed to be an emotion-induced memory trade-off. One
of the main findings out of all of this was that individuals who have PTSD were
more likely to remember positive and negative items rather than neutral. One of
the main things that this study included that is not often considered is
looking at individuals with trauma-exposed control group that don’t have PTSD
to show the differences in both the emotional and cognitive processing that
takes place. So, in other words in delved into the realm of how extreme or
repeated stress without PTSD alone can cause certain changes in memory. Overall,
participants with PTSD did have a larger memory trade-off when compared to trauma-exposed
controls and this was because of the item-background difference between both
the emotional and neutral items that caused this decrease for the
trauma-exposed controls. This all shows that the emotional memory trade-off at
least may be explained by the experience of trauma and the presence of PTSD.
Grella had ended her talk with some future aims and one was to see develop
novel memory modulation strategies that target these circuits to alleviate some
of the dysregulations and to ultimately restore cognitive abilities. Using this
aim and the research she had found that were presented from her talk, this
research of memory trade-off can be studied further with in terms of its circuits
in comparison to the control group that can lead to later on a unifying concept
of psychiatric disorder to help individuals effectively.
References:
Grella, Stephanie.
(2021, November). The stability and flexibility of memory traces in
psychiatric disease-like states. Talk presented at Loyola University
Chicago, Chicago, IL.
Mickley
Steinmetz, K. R., Scott, L. A., Smith, D., & Kensinger, E. A. (1AD, January
1). The effects of trauma exposure and posttraumatic stress disorder (PTSD)
on the emotion-induced memory trade-off. Frontiers. Retrieved December 16,
2021, from https://www.frontiersin.org/articles/10.3389/fnint.2012.00034/full
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