The Origins of Depression: Current Concepts and Approaches

3 and a fraction mayor may not respond to treatment. On the behavioral level, animal research shows that a variety of experimental conditions can induce de­ pression. The same is true in the field of treatment, where pharmacologically highly different drugs can equally alleviate depression in animals and hu­ mans. The question as to whether this is due to a heterogeneity of depressive subjects based on different pathogenetic mechanisms is open to discussion. We can look for common features of