Heart disease, hypertension, cerebral infarction, nephritis, and so on, are inevitable in a person’s life. Even if you are not a doctor, you can tell what these common diseases are, and they are relatively easy to understand. Because these are organic diseases, the so-called “palpable, visible” disease, the basis of the onset of the heart or blood vessels or kidneys appear under the microscope can be found in the cells, structural lesions. When a disease requires medication or surgery, it is easy for doctors to explain and patients can understand. However, except for mental disorders secondary to organic brain diseases, most mental illnesses are “functional” lesions with no abnormal changes under the microscope. This means that the brain is functionally ill! The functions of the human brain are very abstract, and we call them “higher functions”. The function of the kidneys is to filter the metabolic wastes in the blood, the function of the heart is to push the blood through the blood vessels, and the function of the brain is to think, to know, to learn, to govern the activities of the body, and to feel various external stimuli. The functions of the heart, kidneys, liver, and all other organs except the brain can be assessed by objective examinations such as blood tests, ultrasound, CT, X-rays, etc. Only the higher functions of the brain can be assessed by no objective method. That is to say, the good or bad of a person’s brain higher functions cannot be evaluated by machines, and the only one that can be evaluated is another brain with another relevant education! A disease of the higher brain functions is commonly referred to as “mental illness”, which is an invisible disease that can only be indirectly judged by the behavior and words of the patient, and there are no instruments that can directly detect it. The onset and diagnosis of mental disorders are abstract and therefore relatively difficult to treat. Mental disorders such as schizophrenia, in which the entire cerebral cortex is dysfunctional and the symptoms are diverse, cannot be treated surgically. However, for mental disorders such as mental retardation with severe behavioral disorders, drug-refractory obsessive-compulsive disorder, major depressive disorder, anxiety disorder, and other mental disorders with relatively single manifestation symptoms, if long-term medication is ineffective, it is worthwhile to try stereotactic surgery to control the symptoms by improving some brain functions.