Physiological Aspects of Motivation and Reward

Abstract

What are the properties of a biological mechanism that could underlie the general characteristics of motivation and reward? What properties do we need in order to satisfy the requirements of the related concepts of arousal, drive and satiation, approach and withdrawal, positive and negative reinforcement, affective display, and pleasant and unpleasant hedonic experience? We need to envisage a central-neural mechanism that is readily influenced by changes in the internal environment, that receives visceral, endocrine, and somatic afferent inputs from all modalities, and that has visceral, endocrine, and somatic efferent outputs to control or prime response mechanisms in the brainstem and spinal cord. At the same time, the mechanism must have an influence on fore-brain structures to yield the more complex hedonic processes and hedonic experience itself, which we presume to occur at the highest levels of the neural hierarchy. In turn, the central-neural mechanism must itself be controlled by these structures at a higher point in the neural hierarchy.