The aggressive brain: insights from neuroscience

•Virtually all animal species engage in aggressive behavior.•Brain mechanisms for aggression are very similar across species.•Aggression may be an emergent property of a 'social behavior network.'•The neurotransmitter serotonin is important for regulating reactive aggression.•Modern human aggression appears detached from these neurobiological mechanisms.

Aggression is a complex, multifaceted behavior often caused by numerous factors and expressed in innumerable ways. Like all behaviors, aggression represents the outcome of sets of biological and physiological processes emerging from the brain. Although this may seem obvious, discovering the specific neural circuits and neurophysiological processes responsible for engendering aggressive responses has proven anything but simple. The purpose of this review is to provide a brief overview of discoveries in both human cognitive neuroscience and animal behavioral neuroscience that have begun to shed light-literally in some cases-on the heretofore mysterious neural processes and connections responsible for producing aggressive behavioral responses.