The 1990s was known as the Decade of the Brain when many new and important insights given into brain circuitry and functions. Based on an overview of the past, the current decade can be called the Decade of Discovery, because many important molecules, cells, and circuits related to normal and abnormal cerebral functions will be identified for the first time during this decade. One of the major objectives of the Decade of Discovery should be to propose the pathophysiological definition of all mental disorders. Clinical neuroscience is concerned with the etiology and treatment of brain diseases and disorders. Many scientists employ experimental preparations (e.g. cell culture and in vitro and in vivo models) to determine the mechanisms of death and brain disorders and develop therapeutic approaches. Although such fundamental neuroscience has led to many important clinical discoveries, these findings should be tested on patients. Clinical neuroscientists are analyzing brain functions and disorders in order to develop new therapies for the treatment of patients with neurological, neuropsychological, and neurodevelopmental disorders. They work on patients with brain disorders to introduce new therapies to improve brain disorders.