Han and Yiu

While preparing my presentation for these papers, I constantly noted that I didn’t have a large problem with the way that either experiment was performed. Especially the Han paper, which was short and sweet, but still consisted of a structure designed to check off logical boxes step by step. The experiment was clever, and my main qualm with the paper is that it did not address the directionality of neurons expressing high levels of CREB – should the reader be inclined to think of these neurons as important in terms of input from the hippocampus or output to different areas? Although it was not explicit, the closest the authors came, in my opinion, was when they discussed a potential design flaw in their experiment being the neglect of memory reconsolidation after performing a Test #1 (before injection of DT and subsequent ablation of CREB-cre neurons). To me, reconsolidation seems like it should have more to do with hippocampal inputs to the LA rather than any output, but the possibility of this confounding variable was short-lived and thus no directionality was discussed.

The Yiu paper, which was a perfect logical progression from the Han paper, was also extremely clever. Obviously, it is more difficult to test sufficiency (as the authors do in this paper by activating cells) than necessity (as Han does by getting rid of certain neurons). But, I did feel that the decision to use optogenetic techniques as a verification at the end of the paper leads the results to be lacking in subtlety: optogenetic techniques fail to qualify what mechanism a cell uses to activate something. Instead of this broad-stroke measure, the authors could have done a longer and most definitely more expensive experiment to attempt to rule out exactly how these cells become excited to produce the response studied. Overall, though, the Yiu paper also appears to be nearly airtight to me.