I have recently read Seth Godin’s “Linchpin”, a book I heartily recommend you read. In the book, Godin makes numerous references to what he terms the “Lizard Brain”; a part of our brain that tries to protect us and stop us drawing attention to ourselves, and therefore impairs our ability to “get on”. This reminded me of a model of the human brain that I was told about and did some research on a few year ago, that being the Triune Brain. The Triune Brain model was first proposed by American Physician and Neuroscientist Paul D MacLean.
The Triune Brain
MacLean proposed that the forebrain in humans was made up of 3 distinct structures, each relating to distinct evolutionary phases of man kind. Parallels can be and have been drawn with popular culture and spiritualism that talk of people coming from the head, heart or gut; having three planes of conciousness and man has even been referred to as the “Three Brained King” (Gurdjieff) with one brain each for spirit (head), soul (heart) and body (gut). The three structures that MacLean proposed are the Reptilian Complex, Paleomammalian Complex and Neomammalian Complex, each is described below:
The Reptilian Complex is the most primitive of the three structures whose primary function is self preservation/survival. It is also referred to as the Reptilian brain and is the centre for instinctive behaviour, aggression, dominance, territorialism and ritual displays. It is within this part of the brain that the body’s control of vital functions such as heart rate, breathing, body temperature and balance occurs. This portion of the brain is active even in deep sleep, reliable but can be rigid and compulsive. It is the seat of ‘ancestral memories’ and is ‘hard wired’ in such a was that it will repeat the same behaviours over and over again, never learning to adapt its response from mistakes made.
The Paleomammalian Complex, also known as the Limbic system, is responsible for motivation, attention and emotion; Behaviours associated with feeding, fight or flight, social interaction, reciprocity and nurturing reside here. It is capable of recording memories of behaviours that produced agreeable or disagreeable experiences. It is also the part of the brain that controls our value judgments, these are often made unconciously but exert a strong influence on how we behave. This complex helps to control whether you feel positive or negative towards something (valence) and what attracts our attention (salience).
The Neomammalian Complex, or Neocortex, is home to our ability to carry out intellectual tasks. Abilities such as language, abstraction, imagination, planning, modelling, perception and consciousness reside in this complex. The Neocortex is made up of two large cerebral hemispheres, commonly referred to as the left & right brains. This portion of the brain is extremely flexible and has almost infinite learning abilities that has enabled the development of human culture. The left brain generally controls the right side of our body and is responsible for linear, rational and verbal reasoning. Whilst the right brain controls the left hand side of the body and provides us with more spatial, abstract, musical and artistic thinking.
The three complexes do not work in isolation, there are numerous interconnections throughout that allow communication and influencing to take place. The connections between the Limbic system and Neocortex are particularly well developed
Whilst the model is now seen to be outdated by Neurobiologists, who focus their attention on the complexities of the interconnections of the various brain systems, as a model of the evolution of the brain, it still embraced by some Psychiatrists and the public given it’s associations to the evolutionary development from reptiles through early mammals to late mammals and to spiritual/cultural parallels.
I find it to be a useful way of considering how we function and how we react and behave in certain situations. Mmm, that has just reminded me of something else… Watch this space