|Layers of brain in triune|
Big brain=Bigger brain =Biggest brain
The theory was popularized by Dr. Paul McLean in 1952.
So what actually is the truine brain theory?
Three brains in human says you have three in one brain but with different functions, having evolved in stages that are cummulative as in layers.
Reptilian brain: stage 1
Reptilian brain s the ordinary brain that was first to evolve. It was called ordinary because it performs ordinary basic functions that help teptiles live and survive. Reptiles have this layer of brain.
The reptilian brain never evolved or developed past this stage, therefore their brain cannot perform complex cognitive functions like mammals and humans.
Basic functions of the reptilian brain
It has basal ganglia which supports locomotion. It also has some parts that control respiratory and cardiological functions. For example, medulla oblongata, hypothalamus for feeding or hunger signals, as well as sexual or reproductive functions. They only have parts with survival significance
Paleomammalian brain: stage 2
This is so-called because the word ‘paleo’ means ‘old or achaic’ so that ‘paleomammalian’ was used to refer to ‘old or primitive mammal’. As evolution continues, mammals were evolved and the much better bigger brain was genetically wired into their head so they could learn even more better cognitive task, think and hunt for animals.
Paleomammalians have Limbic System, parts of the limbic system are hypothalamus, thalamus, corpus callosum, fornix, cingulate gyrus. The term was coined by Dr. Paul McLean in 1952. According to the theory, example of animals that possess limbic system are Chimpanzee, monkeys.
Basic functions of paleomammalian brain
Limbic system of paleomammalians evolved to perform such functions like regulating emotions such as happiness, sadness, fear, hatred, love and disgust. Other functions include sex, appetite or any of such combinations.
Neocortex: stage 3
Human brain evolved in this stage and combines both reptilian and paleomammalian brain functions with a well developed and organized brain with much cognitive functions. This is the topper most layer of brain as it has the four lobes of the cortex for better cognitive tasks. These lobes are: frontal, temporal, parietal and occipital lobes. The term ‘neocortex’ means ‘new cortex’ with ‘neo’ standing for ‘new’.
Basic functions of the neocortex
The brain of man is able to perform tasks like perception and cordination which are rather more advanced functions, unlike the two earlier layers of the brain.
Reasoning, consciousness, logic, mathematic, sense of judgement, morality, rational.
Hearing, taste, memory formation.
Orientation of the body in space, movement.
Criticism of the Truine Brain Theory
While the three in one brain is intellectually appealing, it has a major flaw which is oversimplification of the human brain, particularly. The brain is a lot more complex than miniaturization into compartments that evolved in layer stages.