The Intracranial Self-Stimulation Procedure Provides Quantitative Measures of Brain Reward Function

Since the discovery of the intracranial self-stimulation (ICSS) procedure in the 1950s, studies using this method have greatly expanded our knowledge of the neurobiology of motivation and reward. ICSS is an operant behavioral procedure in which laboratory rodents prepared with stimulating electrodes learn to deliver brief electrical pulses into brain structures that are part of the brain reward pathway. The ICSS procedure is unique because it enables researchers to quantitatively assess brain reward function in laboratory animals. This procedure has predominantly been used in rats until recently and is now also used in mice. With the recent advances in genetic engineering in this species, the mouse serves as an excellent subject for investigating the neurobiology of reward and motivation. The ICSS procedure, however, is often perceived as too difficult and elaborate to perform in mice, despite the advantages of this technique and the unique research opportunities that mice offer. This chapter describes the two most commonly used ICSS procedures in mice – the discrete-trial current-intensity and rate-frequency curve-shift procedures – and provides suggestions for the successful implementation of ICSS in mice.