Fear Memory Modulation In Mice - John Lambert


The two papers this week both focused on fear memories in mice, particularly in regards to modulating their creation or deletion. Han et al. (2009) utilized diphtheria toxin (DT) to induce apoptosis in targeted neurons in the lateral amygdala as a pathway to selectively remove a fear-associated memory. The paper also demonstrated the importance of CREB in expressing memories. They utilized a variety of controls and similar-treatments to confirm their findings. Yiu et al. (2014) in turn used similar background research to delve into what role CREB plays in memory allocation, how excitation of certain neurons relates to memory trace formation, and how reactivation of excitability-enhanced fear memories could occur. They demonstrated clearly that excitability of neurons before training influences which neurons are encoded into a memory trace and the strength of memory formation. They used a variety of excitability enhancing and decreasing methods to demonstrate this effect. Though the methods utilized in each papers were at times difficult to gain a firm understanding of, these might be my favorite papers in this seminar (thus far).
These papers were both extremely interesting reads, and continued some of the discussion we covered in the articles from last week. Both papers here found some really exciting (that is a pun) things, but their findings are a bit limited. Both papers focused only on the lateral amygdala, which is important to memory and fear, but is not the only structure that is relevant to memory. Related to that, both papers only explored memories that were of auditory fear conditioning. I would be really interested in taking some of the methods used here and exploring how results differ when using different types of memories and in different areas of the brain. Specifically, I would be really interested in visual and olfactory fear and reward conditioning. Additionally, attempting to replicate the deletion of fear memories while keeping different (or similar) fear memories intact would probably result in some fascinating findings. 

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