Models of PTSD: Sial et al. and Allsop et al.

The papers by Sial et al. and Allsop et al. are by far my favorite papers that we have read (particularly the paper by Allsop et al., despite how dense it is). While reading these papers, I did not find myself digging for relevance or for a direct medical application, because I felt that these papers do what we want all scientific papers to do: they attempt to investigate multi-faceted human behaviors through rodent models, well describing a discrete facet and mechanism of fear processing.  

            First, the paper by Sial et al., which presents a new method to examine physical and emotional stress, proposes a novel and exciting way to distinguish emotional distress in rodent models. Although they only use male mice (sad!), as a reader I appreciated the fact that they acknowledged that emotional stress (witnessing another mouse experience an attack) can cause significant posttraumatic stress, depression, and stress-related disorders, in much the same way that physically experiencing the attack does. I found it particularly interesting that the physical stressed groups exhibited notably higher corticosterone levels than the emotional stressed groups with acute stress (40 minutes after a single defeat session), but the levels of corticosterone between PS and ES were almost the same in the presence of chronic stress (24 hours after exposure). A similar trend was also noticeable with the social interaction test. These data allude to the fact that when it comes to chronic stress, emotional and physical stress can be equally detrimental and cause long-term consequences. As we discussed in class last week, papers like this one are important to the field of neuroscience and psychology because they validate the trauma that many people experience, even in the absence of physical stress. As we know and as this paper proves, emotional stress can be just as taxing as physical stress.

            The paper by Allsop et al. delineates between observational fear conditioning and classical fear conditioning, concluding that the ACC àBLA pathway is implicated only in observational fear conditioning. What I particularly appreciated about this paper was that they used 5 different models of “observers” to represent many different forms of observational learning (and they did an excellent job of explaining all of this in the first figure). The authors explain that different experimental groups exhibited variations of a stress response; for instance, the naive observer mice (NO) showed increased freezing during conditioning but not on the test day, while the experienced solo (ES) mice showed place avoidance which was not sufficient to cause freezing during the cue. I believe that these experiments speak to the wide range of responses to aversive stimuli, and the ways in which different levels of experience with this aversive stimuli can result in different behavioral effects. In the context of PTSD specifically, this alludes to the fact that there is no black or white, but rather lots of grey middle ground, when it comes to the ways in which individuals display signs of trauma and distress.