Response to Articles-Week One

I found it interesting that the article by Santarelli et al. was one of the papers featured in the Bessa et al. paper. Not only was it cited for previous work, but it was directly brought up in the introduction of Bessa et al. being described as controversial based on their posit that neurogenesis in the hippocampus causes behavioral improvements seen due to antidepressant administration, and that Bessa et al. goes on to discredit this statement based on research done by a different group, stating that the stress used to cause the depression-like symptoms is known to reduce neurogenesis. Despite this, the paper by Santarelli et al. seems to be one of the most ground-breaking of the time, being one of the first to correlate behavior with neurogenesis. They show that, though previously unclear, disrupting neurogenesis in the hippocampus during treatment with antidepressants results in absence of the behavioral modifications that have been associated with such treatments. This result does point in the direction of modulation of behavior coming from hippocampal neurogenesis, but this paper does not address the possible neurogenesis more recently found to be occurring in the prefrontal cortex, which the paper by Bessa et al. does discuss. Though both papers are focused on neurogenesis, Bessa et al. makes the discovery that neurogenesis is not necessarily the principle factor in behavior resulting from antidepressants. After pharmacologically inhibiting neurogenesis, they found that the depression-like behaviors learned helplessness and anhedonia were still observed following antidepressant treatment. The difference in this portion of the studies is that Santarelli et al. used X-irradiation to destroy these cells irreversibly, whereas Bessa et al. used a reversible method, resulting in a trend that Santarelli et al. was unable to discern. Because of their results, Bessa et al. proposed that the real culprit behind behavioral improvements following administration of antidepressants is reestablishment of neuronal plasticity in the hippocampus and prefrontal cortex.