Subcortical refers to structures or regions lying beneath the cerebral cortex of the brain. There are several ways to describe these areas using different synonyms such as subcerebral, subcortical nuclei, infracortical, subcortical structures, and subcortex. In addition, some scientists use the terms "deep brain structures" or "lower brain regions" to describe the same set of brain areas. These regions are essential for regulating basic physiological functions, such as breathing and heartbeat, as well as controlling emotions and movements. Understanding the function of subcortical areas is essential for treating a variety of neurological and psychiatric disorders such as Parkinson's disease and bipolar disorder.