Evaluation of motivational effects induced by intracranial self-stimulation behavior.

In the runway model of intracranial self-stimulation (ICSS) experimentation, the experimental animal is timed in running a fixed distance to depress a lever that releases electrical stimulation to an electrode implanted along its medial forebrain bundle. This ICSS has both a reward and a motivational component. Using the runway method and priming stimulation, we designed an experimental method for directly measuring motivation. An assessment of pharmacological agents that are known to influence motivational states was also undertaken. Using the experimental methods that we created, we observed prominent changes in running speed when animals were exposed to methamphetamine and nicotine. According to these data, the runway method employing intracranial self-stimulation behavior may be useful for the evaluation of substances that act on motivation. We review the underlying neuropharmacological and anatomical functions associated with our experimental methods. We hope that this technique will be used to scientifically evaluate the impact of drugs and/or therapeutic interventions on human motivation.