Ramirez et al

This week while reading Ramirez et al on creating false memories in the hippocampus, I was very impressed by their experimental use of optogenetics. I thought that their use of doxycycline to modulate transcription of ChR2 was a very powerful technique that allowed numerous complex manipulations that otherwise wouldn’t have been possible. I think in general they did a really good job of digging deep into the problems they were exploring, and confirming their conclusions with numerous controls, despite the fact that it made their experimental schemes significantly more complex and difficult to parse out as the paper went on.

            One of their more interesting data points, in my opinion, is in figure 3A. The group of mice that had been fear conditioned in context B with the light on didn’t learn to be afraid of context B very well, but showed much more freezing when the context A neurons were activated. I thought this concept of overall impaired learning when multiple conditioned stimuli are presented was very interesting, and something I hadn’t necessary expected. Second, the group of mice that had been fear conditioned without light showed reduced freezing when their context A neurons were activated. Essentially, thinking about a place where nothing bad had ever happened made them less afraid. I thought this point was particularly interesting, especially in reference to PTSD research, and worth further investigation in future research. While the majority of this paper was looking into how “incorrect” fear can be expressed in places where it shouldn’t be (which is interesting and very useful for PTSD research), this bit of information showed how “correct” fear could be reduced, which seems like a very relevant point for the treatment of PTSD. I think in some ways, reducing fear by thinking of someplace happier is very intuitive, and this data did a nice job of confirming that to be true.