Pollak et al. (2008) & Li et al. (2010)

The article by Pollak et al (2008) is dense in that it goes over many different individual experiments in one paper, and I think it somewhat makes the paper more difficult to digest. Despite the thickness of it, I believe that it is a very comprehensive paper, looking into every aspect of learned safety (LS), from behavioral aspects to immunohistochemistry. Obviously, as some will certainly point out, more could be done to determine the behavioral aspects of LS in addition to the forced swim test, however I think this one behavioral test effectively contributes to the paper and adds relevant and significant data that aids in their study of the bigger picture of LS. I did have a few comments on this paper despite the overall feeling of approval I got. In Figure 1, the base level of freezing in the LS groups is consistent across the board during pre-CS, except in 1D. I am confused as to why it is so much lower with little error, especially after the subjects being exposed to fear conditioning. On that same note, I am confused about why the naïve controls in 1C have such a low level of freezing to start with. I speculated that they may be exploring a novel environment, but the amount they froze in 1C and 1D in presence of the CS is only heightened to the level of the previously mentioned consistent baseline value for LS subjects pre-CS. In addition, I am wondering about the statistical significance in Figure 3B between the vehicle + CS group during CS and the fluoxetine + CS group pre-CS. I think it’s interesting that these values seem to be similar, but it is not mentioned in the paper.

In the Li et al. (2010) paper, I was immediately impressed with their choice of behavioral paradigms and types of neurological evaluation based on the responsiveness to chronic stress only, the topic of the paper. I notice that they do a lot of qualification of choosing the methods they did, but I find it helpful and it significantly increases my trust in their methods and the significance of their results. I found very little to fault in this paper. It was well organized, comprehensive, and easily readable in my opinion. The only comment I have is about possible future research. I think it would now be advantageous to develop a paradigm of chronic ketamine or Ro 25-2981 administration and determine how it may effect animals longitudinally, longer even than 7 days, to determine the long term effects of NMDA blockers on long term depressive symptoms.