Background"Normal" aggressive behavior has very specific objectives: to maintain the individual's physical integrity, predation for subsistence purposes, vital space or territory preservation and perpetuation of the species. These functions are perfectly summarized in the term expressed by Walter Canon 1 , "fight or flight". Human aggressiveness shows a common pattern of behaviors similar to other animal species and is only activated in the presence of a threatening stimulus. This innate behavior is associated with the limbic system. The first description of the existence of an "emotional brain" was made by Christfried Jakob 2 in 1907-1908, laying the groundwork for subsequent contributions by James W. Papez in 1932 and Paul D. MacLean 1 . These concepts culminated in the integration of the limbic system and gave a better insight, between physiology and anatomy, in the generation and control of behavioral and emotional patterns. On the other hand, "unnatural or pathological" aggressiveness is an exaggerated behavior that occurs disproportionately in the presence of a stimulus that normally would not imply danger. This symptom is present with certain frequency in some neurological and/or psychiatric conditions.