Triune Brain Theory

Dr Paul Maclean, a leading neuroscientist, developed the famous Triune Brain theory for understanding the brain in terms of its evolutionary history. According to this theory, three distinct brains emerged successively in the course of evolution and now co-inhabit the human skull. These three parts of the brain do not operate independently. They have established numerous neuro pathways through which they influence one another. This interplay of memory and emotion, thought and action is the foundation of a person’s individuality. The Triune Brain theory leads to a better understanding of the survival instinct such as the fight or flight  response and its ability to override the more rational neocortex.

Reptilian Brain

The oldest of the three, controls the body's vital functions such as heart rate, breathing, body temperature and balance. Our reptilian brain includes the main structures found in a reptile's brain: the brainstem and the cerebellum. The reptilian brain is reliable but tends to be somewhat rigid and compulsive.

Limbic System

Emerged in the first mammals. It can record memories of behaviours that produced agreeable and disagreeable experiences, so it is responsible for what are called emotions in human beings. The main structures of the limbic brain are the hippocampus, the amygdala, and the hypothalamus. The limbic brain is the seat of the value judgments that we make, often unconsciously, that exert such a strong influence on our behaviour.


First assumed importance in primates and culminated in the human brain with its two large cerebral hemispheres that play such a dominant role. These hemispheres have been responsible for the development of human language, abstract thought, imagination, and consciousness. The neocortex is flexible and has almost infinite learning capabilities