Intensity and Duration in Brain-Stimulation Reward

Abstract

Electrical stimulation of certain regions of the vertebrate brain produces behaviour analogous to a powerful motivational state. The electrical stimulation that produces this behaviour is described as rewarding brain stimulation. When an animal is placed in a situation in which it can control both the initiation and termination of rewarding brain stimulation, an alternation often occurs between periods of stimulation and periods of no stimulation which has been termed shuttling behaviour. The research program reported here examined the relationship between shuttling behaviour and the intensity and duration of rewarding brain stimulation. ...The series of experiments reported here examined in detail the relationship between the selected durations and the intensity of stimulation, and also evaluated hypotheses concerning the termination response in terms of how well the observed relationships may be explained. ... Two models that satisfactorily accommodate the main features of shuttling behaviour are discussed in relation to how the behaviour might be produced. The results supported a two system substrate for brain stimulation reward, which in turn, could support either a reward/aversion or a reciprocal inhibition model. From a neurophysiological point of view, the interaction of the two systems and the timing of the termination response might be best interpreted in terms of adaptation and the arousal of an inhibitory system. The timing of the initiation response appears to depend on several factors including the presence of various stimulus contingencies.