The place of the Triune Brain in psychiatry.

MacLean's pioneering concept of "The Triune Brain" began to emerge in 1949 with his publication Psychosomatic disease and the "visceral brain", followed in 1952 by Some psychiatric implications of physiological studies on frontotemporal portion of limbic system (visceral brain). This shows that his seminal ideas grew out of his astute observation of psychiatric signs and symptoms. Later on, he observed the broad spectrum of human epileptic seizures and its cause in the limbic system. A large variety of uncontrolled feelings and emotions, together with bizarre motor behavior, is elicited by seizures in the hippocampus and other limbic structures.Meanwhile, based on the triune brain model, a new approach to psychopathology has taken shape. It is the evolutionary perspective of mental diseases such as the major psychoses, anorexia nervosa, anxiety disorders, and also brain diseases such as Parkinson's disease or Huntington's disease. Many mental illnesses are marked by severe deficits in social behavior and social communication. The social communication system disintegrates, especially in the major psychoses. The response choices to social or other external signals in a given situation become limited or even distorted, and reasoning is no longer part of decision making. The emphasis of this contribution is on the disintegration of social behavior in psychopathology, based on evolutionary psychiatry. MacLean's concept provides valuable insight for understanding the biological roots of human social behavior and communication. It is time to uncover the ties between the natural and the social sciences.