Week 5

After reading both of these papers, I feel as if some of the questions I have always had in neuroscience, such as how information is processed and ordered in salience, have been answered in a way. Maybe this is because I haven’t had the opportunity to take a computational networks class yet, but both of these papers seem to me like they might relate to that topic. I found the first paper a lot easier to understand than the first. From the 2008 paper, I thought it was really interesting that the fear neurons found in the BLA were able to send inputs to the mPFC but did not receive any projections from the mPFC. Thinking about this in a more philosophical sense (and I do not know if this would be correct) it seems like the fear neurons act to alert the higher cortical areas of the fear being experienced, but they are not capable of sending mediating outputs from the mPFC to the amygdala. It seems like these fear neurons would not be able to be calmed by higher cortical control over the situation, like in the case of OCD or anxiety disorders, when people become anxious over non-threatening stimuli. However, the researchers found that the extinction neurons have bi-directional connections, meaning that perhaps these neurons are capable of mediating a fear reaction. So, once one has learned once that a stimulus is not actually threatening and has created extinction neurons for that stimulus, perhaps input from the mPFC to the amygdala can dampen any fear response caused by the initial reactions from the fear neurons? Maybe this could be an avenue for therapeutic research. While reading the first paper, I noticed that the researchers sometimes used BA and BLA interchangeably. I know that they are somewhat overlapping areas, but would be interested to learn more about what makes them different and whether they should be distinguished during writing or not. I was also curious about where exactly fear memories are stored? If the BA has no effect on the expression of fear memories and only has to do with the context-dependent transitions, is there an area dedicated solely to the storing of an emotional memory? Would it have to be anatomically distinct from the amygdala?

I found the 2014 paper a lot more difficult to understand. Throughout the paper, I understood what was being done to create the results, but I wish the authors had clarified what significance each result had. It was difficult to keep in mind the big picture, and remember what each change in spiking activity or oscillation synchronization meant. In the end, it was pretty cool that they were able to determine that the presentation of the fear tone caused the PVINs to mediate the theta phase resetting and synchronization of principal neurons, which led to the actual fear expression behavior. At the end of the paper, the authors mention that phase resetting of oscillations might be a method to control the transmission of downstream information and create salience hierarchies. This made me think of memories, and how while reading previous papers I had wondered how certain memories are prioritized and given more significance. Perhaps oscillation synchronization and the resulting output connections play a role in determining these factors in multiple thought processes.