Week 2 blog

The use of optogenetics has allowed researchers to select specific areas of the brain and induce firing patterns to determine what neuronal activity causes a depressed phenotype. Both the Chaudhury and Tye article adequately show that the VTA and NAc work together in different firing patterns to both relieve and induce a depressed phenotype in mice. Both of the papers provided experiments that cross-checked their findings to make sure they were not due to other factors. While these papers used cross-checking of their experimental results, they both identified an area of concern in these animal models that they did not address experimentally.

               Tye et al. stated that “different stressors can cause opposite responses from VTA neurons depending on pre-exposure and severity.” Similarly, Chaudhury et al. insinuated that their experimental results were influenced by this same pre-exposure by saying “reactivation of the memory of the previous social-interaction test resulted in those NpHR-injected mice spending longer times in the interaction zone.” Both of these papers mention that these mice who are constantly used in these experiments may be influenced by previous memories of it, and thus are more inclined to act a certain way due to these memories rather than what is actually being tested. To me, this is troubling not because of the possibility of this effecting results, but because it was not experimentally addressed by the papers. In order for both of these papers to hold more weight I think that it should be proven that memory does not have an impact on these individual’s behaviors, and thus the behaviors observed are indeed due to a depressed state. There may also be a procedure to follow that allows for these animals to “forget” their previous experimental sessions, as to ensure their experimental results are not influenced by memory factors. One way to do this may be to expose an experimental group of mice to a noxious or pleasurable stimuli and evaluate them at differing time intervals to see when it is they “forget” the stimuli. I think this would make both of these papers stronger by ensuring that their results are coming from what they are testing and not memories of previous experimental sessions.