Brain-stimulation reward after twenty-five years.

Abstract

Brain self-stimulation was first demonstrated when it was observed that a rat returned to the place in an open-field where it received electrical stimulation of the forebrain (Fig. 1). Subsequently, when rats were tested in a Skinner box it was shown that they would press a lever to initiate electrical stimulation of limbic and hypothalamic sites (Olds & Milner, 1954). The brain stimulation apparently had the properties of positive reinforcement or reward, a conclusion subsequently confirmed in experiments in which animals were observed to run along a straight alley, to traverse a complex maze, or to cross a painful shock grid to obtain brain-stimulation reward (Olds, 1958). During the next few years brain self-stimulation was reported in other species (e.g., cat, dog, gerbil, goat, guinea pig, hamster, monkey, rabbit) including the human.