In recent years, various problems of addiction have become prevalent in the world, and the situation has become more serious. Addiction is a condition that arises when the ingestion of an addictive substance or the performance of a particular behavior gives one pleasure, but the continued usage or behavior becomes compulsive and interferes with normal life. While it is very important to uncover the mechanisms underlying addiction, there are still many things that remain unknown.
More than 60 years have passed since Olds and Milner discovered intracranial self-stimulation (ICSS) behavior, and the ICSS method has become a powerful tool to elucidate the neural network of the reward system. Previous studies have shown that the mesolimbic dopamine system, which is projected from the ventral tegmental area to the nucleus accumbens and the prefrontal area, is important. In recent years, although self-administration tests and conditioned place preference tests have been widely used as drug-dependence evaluation methods, ICSS method that electrically stimulate the medial forebrain bundle (lateral hypothalamic region) of the mesolimbic dopamine system could be also useful tools that can provide different insights in assessment of addiction. In this symposium, we would like to discuss the advantage and disadvantage of ICSS method in research of addiction and reward-system neural network analysis, in light of previous research and recent trends using the ICSS method.