An Introduction to the Neurobiology of Emotions and Social Behavior

Emotions serve to facilitate decision making, and to organize and to motivate behavior. The advent of new techniques for investigating the structure and function of the brain, particularly the introduction of neuroimaging tools that allows one to study localized brain function during prescribed tasks, has led to a rapid improvement in the understanding of the neural substrates of emotional processing. The systems that have been put forward for describing emotions can be thought of as falling into two groups: categorical and dimensional. From a neurobiological perspective, the significance of these alternative approaches rests in the different ways in which they relate to associated theories concerning the neural underpinnings of emotion. Categorical systems are more numerous than dimensional systems and assume that there are a certain number of discrete, "basic" emotions; other emotions, if recognized, are seen as reflecting either differing levels of intensity. An alternative to a categorical system for describing emotions is a dimensional system. Although the categorical and dimensional systems are often characterized as constituting almostmutually exclusive alternatives, they can in some instances be regarded as complementary. Shifts in emotional state can be triggered by external or internal stimuli, with the latter category including thoughts, memories, or even one's conscious awareness of feelings generated by an antecedent emotion. Emotional appraisal can occur consciously or unconsciously, and studies on both human and non-human animals have provided strong evidence of a critical role for the amygdala in this process. © 2012 Elsevier Inc. All rights reserved.