Skip to main content

Post 5: Modelling PTSD

By
Sial et al examines the paradigm of emotional stress (ES) by have mice observe another mouse undergo physical stress (PS) through the abuse of an aggressor in the vicarious social defeat stress (VSDS) model. While Sial’s research is intuitive on larger scale, big picture objective with many examples of PTSD evolving from witnessing a traumatic even in humans, I am not sure if mice have as complex networks as humans that make this as clear cut. In humans, PTSD from witnessing a traumatic event is common as the complexity of human emotion and subsequent networks, but in mice defining “emotion” is more complicated because we cannot ask a mouse how it is feeling. Nonetheless, Sial’s study captured that witnessing a traumatic event can induce a depressive like phenotype similar to the mouse undergoing the PS. Conceptually, I wonder how much of the induced phenotype is from emotional stress so much as fear of being attacked itself. To capture a glimpse into a more empathetic response, I think it would have been interesting to explore how mice with social bonds reacted to one another being hurt, if it would have increased the loss of weight and corticosterone levels. Additionally, I wish that the study had utilized more measures of depression and stress than weight change, corticosterone levels, elevated plus maze, and social interaction test. It would have been interesting to visualize the brains of these mice as well to see if there were any observable differences in activation patterns of control, ES, and PS mice. Lastly, I would have liked to see potential measures of recovery time and how emotional and physical stress mice differed in this. 

Allsop et al answered many of the questions that Sial’s paper spurred, specifically they included the neural response observed in the observational fear paradigm. The researchers examined many many aspects of the observational fear learning that were able to capture an interesting story of the observational fear learning pathway. Again, the paper solidified that observational, or the correlate of emotional in Sial’s paper, fear learning can have just as detrimental effects as physical stress. They took it a step further and examined neuronal activation and observed that the ACC à BLA pathway was necessary for observational fear conditioning but not classical fear conditioning. This detail specifically stood out to me; it makes sense that the BLA would be involved in fear conditioning and emotion, but the ACC must play a crucial role in being able to recognize that traumatic event is taking place. Lastly, Allsop also touched on the fact that observational learning was more robust with prior experience – this too makes sense conceptually given prior experience could more easily recall that traumatic event. I think it would have been interesting to look at the hippocampus as this is technically still learning and how robust the projections from the BLA to hippocampus are in each context and group.   

Overall, as we have discussed in class, while this may not lead to any treatments any time soon, any form of understanding we can gain from these papers helps us understand neuropsychological disorders. Especially in the context of PTSD, where the inciting incident for many victims has been questioned and criticized, I think these papers lend support to the fact that an individual does not need to undergo physical stress for PTSD to develop. 

Comments

Post a Comment

Popular posts from this blog

Week 2- Dopamine Modulation of Depressive-like Behaviors

By
The Chaudhury et al paper explored the neural circuit mechanisms involved in the dopamine modulation of certain symptoms of depression. In this study, the researchers looked at social interaction and sucrose preference as part of their social-defeat paradigm, which has been shown in the past to be indicative of depressive-like behaviors. Although I initially did not completely see the connection between the social-defeat stress model of depression and the tonic vs phasic firing of dopamine neurons, it seemed that susceptibility and resilience to stress played a role in the functional/behavioral effects of dopamine firing. It was interesting to see how chronic mild stress with phasic firing of VTA dopamine neurons converted even resilient mice into susceptible mice.  The Tye et al paper similarly looked at the dopamine modulation of depressive-like behaviors, focusing on motivation with the forced swim tests and open field tests, followed by measurement of anhedonia by quantifyi...
Post a Comment
Read more

Sial & Allsop

By
Sial et al. derived a novel approach for studying what they deem vicarious defeat stress (VSDS) as a model for MDD, PTSD, and other mood-related disorders as an alternative to the classical CSDS paradigm. Using adult male mice, they demonstrate that their model induces a robust and measurable social avoidant phenotype as well as other stress and anxiety related behavioral outputs. Their subsequent rescue study with chronic fluoxetine treatment shows reversal of the behavioral phenotypes and emphasizes the predictive validity of the model. Allsop et al. found that BLA-projecting ACC neurons preferentially encode socially derived aversive cue information by encoding the demonstrator’s distress response during observational learning, hence enabling acquisition of negative valence of cue by BLA neurons and behavioral output. In order to test their hypothesis, Allsop et al. used an observational fear conditional paradigm to create association between a conditioned stimulu...
Post a Comment
Read more

Buffington and Reber

By
Buffington et al. explore a mechanism by which maternal obesity can induce neuronal and subsequent behavioral disorders. Using a model of high-fat diet (MHFD)-induced obesity, the authors showcase the strong connection between the brain and the gut, and its impact on behavior. The findings are provocative; by exposing these offspring to the microbiome of control offspring, there was evidence of a rescued observed behavioral phenotype. Furthermore, a phylogenetic profiling of the gut microbiome revealed a decrease in L. reuteri within MHFD offspring, and introduction of live L. reuteri into the drinking water shows successful rescue of the behavioral issues in the MHFD offspring. L. reuteri-induced expression of oxytocin within the paraventricular nuclei of the hypothalamus provides a potential mechanistic explanation for the behavioral changes. I thought this paper provided robust support for the hypothesized interaction between the gut biome and the developing CNS, with tremendous po...
Post a Comment
Read more