Week 4

This week's papers were interesting in that they were incredibly similar in the overall mechanisms they were trying to prove. I read the Yiu et al. paper first, and I think it was necessary to fully understand the area they were studying and why. The Han et al. paper, while sufficient in data, was not as clear or thorough in their explanations. However, as we've discussed in class before, this may be due to journal standards - Science may be more minimal while Neuron requires a more detailed write up.

The first concern I had with Yiu et al.'s paper was their evidence that CREB and dnKCNQ2 enhance excitability at the cellular level. They stated that cell culture and ex vivo work confirmed that these do in fact increase excitability. Whether this is sufficient to say that these mechanisms occur similarly in vivo is unclear. However, after further in vivo experiments targeting high/low CREB neurons and measuring their excitability in vivo, the cellular hypothesis is more convincing. Another thing that stood out to me in this paper was the "randomness" of the recruited neurons. I don't believe this is a criticism against the design of the paper, I'm more just curious as to why a small subset of neurons in the lateral amygdala is responsible for encoding fear memories. While the paper points out that they're not technically random, they're primed by CREB activity, but I'm surprised that there's no common thread of synapse/dendrite connectivity, specific area in the LA, etc.

Han et al.'s paper was a great supplement to the other paper. I believe both papers got at the fact that specific high-CREB cells in the LA are responsible for encoding fear memories, but they proved it in almost opposite ways - one removing these neurons and one creating a high-CREB neuron. After reading Han et al.'s, I came up with a couple larger-picture questions on the topic in general. Most prominently, because the two papers used similar fear memories, are these high-CREB LA neurons just responsible for encoding fear memories? While I have limited exposure to this type of research and there may be other papers on various memories, I think it would have been helpful to have various types of memories tested. Additionally, the two papers caused me to question - what is the point of low-CREB neurons? We were always taught that, in the brain, if you didn't use it you lost it. If these neurons are not encoding memories, what would they be for? While the answer to that question may be limitless, I think it's an interesting idea. Also, why does high-CREB make these neurons good candidates for encoding memories in the first place? What about a high-CREB environment is "attractive" for encoding? Just some ideas that I hope could be answered/discussed in class!