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Blog Post 4: Han et al. 2009 and Yiu et al. 2014

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The papers by Han et al. and Yiu et al. demonstrate that neurons with increased CREB in the lateral amygdala (LA) are preferentially recruited into the memory trace, specifically with respect to a fear memory. The paper by Han et al. from 2009 underscores the necessity of this specific neuronal subpopulation by ablating these neurons, which resulted in a loss of the fear memory. The paper by Yiu et al. from 2014 builds on this further, explaining that increased excitability in LA neurons resulted in enhanced memory formation. While I believe that both papers provide very convincing and exciting data, I have a hard time understanding how this can be applicable in any clinical setting. 
The concept of ablating only the neurons that overexpress CREB and that are allocated to a specific fear memory, in order to permanently erase that memory, sounds lovely, especially with regards to treatment for PTSD. However, how this could ever be done in humans is beyond me. I do believe that the findings presented in both of these papers are important to a greater understanding of the way neurons in the amygdala encode a specific memory, but I think it is far away from being applicable clinically. Obviously we cannot ablate populations of neurons in humans, but do these findings point towards the need to target very specific brain areas when treating disorders like PTSD? Specifically, does this have any implications for possible uses of TMS to target circuitry in the BLA and hopefully relieve the symptoms of PTSD?
Also, the paper by Yiu et al. addressed the baseline level of anxiety of the mice to demonstrate that the freezing was caused by increasing excitability in LA neurons, rather than an overall increase in anxiety. To do so, they used open field and elevated plus maze, and their findings suggest that there was no significant difference in the levels of anxiety in the CREB, dnKCNQ2, or GFP (control) mice. However, they used both male and female mice in their study, and their only measure of fear was freezing. As we know, male and female rodents often display different phenotypes of fear and anxiety, so I would have liked to see a more in-depth analysis of fear expression and anxiety levels. 

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