Week 5

This week I felt that the papers were the most challenging we had read so far. However, I think because we read other papers that utilised fear conditioning experiments, it was a little bit easier to not have to learn a new test or experimental design.

The first paper I read was Herry et al.'s Switching on and off fear by distinct neuronal circuits. Towards the beginning, I was having a hard time understanding the overall experiment and how each section was relevant to their hypothesis. However, by the end of the paper, I began to understand the larger picture and how the experiments worked to prove how the two circuits were distinct and integrated into the PFA/hippocampal network. Based on my limited research background, scarcer in neuroscience, I had a hard time understanding a lot of the figures because I haven't had a lot of exposure to circuit and neuronal activation research. Because of this, I relied heavily on the text, which was organized nicely in the different sub-titled sections that made it easier to follow. One way I thought this paper could have been stronger was if they could selectively inhibit fear or extinction neurons, as opposed to the muscimol inhibiting the entire BA. I think isolating these neuronal circuits could give clarity to its role in fear reactions and extinction. In addition, (and I'm not sure how this would be done) but I think if you could severe the connections between the hippocampus or the PFC and the basolateral nuclei, it would be interesting to see how this severed connection impacts fear extinction and/or renewal. Finally, it would be interesting to see if different types of fear memories acted upon different circuits. I know that one part of the paper distinguished between two different conditioned stimuli and the ability for the circuits to discriminate between each. But I think it would supplement the paper to include a different type of fear test to see if these fear and extinction circuits follow the same pathways, are maybe clustered together in a different area, or also intermixed between the already-established neurons.

As for Courtin et al.'s Prefrontal parvalbumin interneurons shape neuronal activity to drive fear expression, I had a very hard time following the experiments and the overall message of the paper. This may be due to my lack of knowledge on parvalbumin interneurons, as well as understanding of theta oscillations. One (of many) questions that I had at the end of this paper was what is the point of phase resetting? While they gave various notes on it in the very end of the paper, I wasn't really connecting how, cognitively, phase resetting is important.