Sunday, February 26, 2017

Week 5

With the paper from Courtin et al., I struggled the hardest to understand the actual methods than I have this whole semester. It was interesting because the paper from Herry et al. was especially easy to map out each experiment and its findings. Though the methods of the papers differed in comprehensibility, I found the overall results of both to be very interesting. Though I think understanding the complete circuits of the brain is extremely important, this was the first time I've read papers focusing in more on the exact projections and the communications between specific neurons which I thought was pretty cool.
After reading Herry et al. I was intrigued by the switch mechanism they discovered. I wasn't completely convinced whether it was an actual switch or just a coincidence, seeing as it would make sense for the activity of fear neurons to be higher during fear conditioning and the activity of extinction neurons to be higher during an extinction of a memory. I liked the papers logical progression of experiments, however thought the last one looking into the effects of inhibiting the BA was rushed and potentially warranted a paper of its own.
After multiple readings, I finally realized Courtin et al. was studying the connections within and the mechanisms of that switch (which made sense, since during my googling to understand the paper I saw that Courtin studied under Herry). The switch is confirmed when they show that inhibiting the PVINs through optogenetics disinhibited the PNs, which induced freezing even after extinction had occurred. I understand that resetting oscillations is important for fear expression but I'm excited to learn more about it and its mechanisms in class discussion this week.
These papers really peaked my interest of the neuron interactions going on within certain circuits. Could this switch mechanism be involved in other behaviors, especially ones linked with the PFC? And what determines whether a behavior might be regulated by a "switch" versus just the activation and deactivation of one set of neurons?

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