Observational Learning, Sial & Allsop

Vicarious stress, which Sial et al and Allsop et al studied in their experiments, is an important component of understanding psychological disorders. Since the beginning of psychology as a field, psychologists have published many different theories of emotion and learning and the mechanisms that underlie their behavioral responses. However, recreating these theories to ethically test their validity in rodents has been, and still is, a challenge. Through their observational learning tasks, Sial and Allsop show ways in which learning vicariously can elucidate the biology that underlie PTSD-like phenotypes.

Sial et al propose a novel vicarious social stress paradigm in which mice can experience emotional stress rather than physical stress, as other forms of social defeat stress include. This model of emotional stress does a nice job of showing that emotional stress, although it may not be immediately apparent, has similar effects on a rodent’s corticosterone levels and performance in the elevated plus maze. In other words, emotional stress produces similar physiological and psychological changes in rodents as physical stress. Vicarious social stress tests are not the end all, be all method for studying emotional stress, but it does provide a good starting point from which other paradigms can refine its parameters to understand different variations of emotional stress such as PTSD.

Allsop et al study another form of vicarious social stress through observational learning and take their study a few steps further than Sial et al and study the circuitry behind the behavioral effects they see. Although robust effects were seen through inhibiting the ACCàBLA projection, this does not convince me that this single circuit is what’s necessary for observational learning in their behavior task. Similar to the results of the Tye and Chaudhury papers on depressive-like phenotypes mediated by the VTA (week 2), there could be other studies that vary slightly and come up with different results for closely related concepts. Because the amygdala is such a complex structure, I’m sure there are other circuits or forms of signaling that could contribute to observational learning. Also, it’s interesting that there is no effect seen by inhibiting the reciprocal circuit, BLA à ACC. This makes me wonder what other brain structures are responsible for consolidating an observational memory, and how it migrates.

After reading both papers, it leaves me with a few questions about each paper’s experimental setup. In the Sial paper, they briefly mention that previous studies of vicarious stress in rats were ethically invalid because the witnesses were housed with the rats that they were witnessing receive foot shocks. However, in both papers, I didn’t find the methods on how Sial or Allsop housed their animals besides the statement that Allsop et al housed their mice in pairs. To what extent does social support with their cage mates help the stressed mice in each study cope with stress? If mice are housed with more mice and more enrichment, would this help alleviate stress for both the witness and the shocked/physically stress mice?