Thebrainas a complex organ, hasmillions of years in continuous evolution, where each stage of its evolution has not disappeared anatomically, but has been superimposed by more recent ones and withfunctions of greater complexity. The oldest layer that is part of the “Triune Brain Theory” isthe reptilian brain.

In the following article, we will explainwhat the reptilian brain consists of, we will mention its main characteristics and we will describe its functions.

What is the reptilian brain?

The reptilian brain was described and developed in the “Triune Brain Theory” or “Three Brains Theory“(1), developed by neuroscientistPaul MacLean(2). In this model, the brain’s main function is to maintain the survival of the species. The two remaining components of this theory are theemotionalbrain orlimbic systemand therational brain.

This theory hasmany followersin the scientific community, sinceit could be linked with the ideasofCharles Darwin(3) on the evolution of humancognitionand the idea of the reptilian brainhas permeated other specialties otherthan science. (4)

You should know: For some authors, the reptilian brain is a myth, because they consider that the brain being such a complex organ candivide and separate in its functions, and another thing is thatMacLean’s theory lacks scientific support.

What does the reptilian brain do?

The reptilian brain according toMacLean’s theory, is in charge offunctions related to survivaland which we mention below:

1. Manage basic survival functions

According toMacLean’s theory, the reptilian brain is responsible for maintaining thefunctions necessary for immediate survival. These functions areeating, drinking, sleeping or reproducingamong others and are in accordance with all animal species on the planet.

Note: This could be understood as programmed automatic responses, which manifest only under the right conditions.

2. Manifest instinctive impulses and reactions

to appear, such as routines that are repeated in the same way depending on the physiological states of the organism.

This is how the automatic reactionsof living speciesarise , and it has been described according to the aforementioned theory that they originate from the evolution of reptiles,being inherited by human beings .

To highlight: In this context, the brain as a whole does not need to think and reflect to eat, for example, since the impulse of hunger is automatic and turns on other organs that activate the desire to satisfy it.

3. Activates the genetically programmed codes

The actions of the reptilian brain are genetically programmed, that is to say that they are inherited through the genes from generation to generation and this behavior remains almost unchanged over the centuries.

4. Controls autonomic functions

Additionally, the reptilian brain is in charge of controlling the autonomic functions of the human organismand of living species, so eating, drinking and reproducing the survival of the human being.

You should know: We are referring to functions such as heart rate, respiratory rate, body temperature and blood pressure, which keep the body in full balance and functioning .

5. Regulates balance and muscle movement

One of the organs that make up the reptilian brain are the Basal Gangliatag. This organ isin charge of the Regulation and Managementof voluntary motor actions. (5)

They serve as an unconscious filter, which selects the movements to be carried out by the locomotor system, specifically helping to control body posture and coordinate the precise movement of the extremities.

Key Findings

  • The reptilian brain was developed in the “Triune Brain Theory”.
  • The reptilian brain’s main function is to maintain the survival of the species.
  • The reptilian brain is made up of the Basal ganglia, the brainstem, and the cerebellum.
  • The reptilian brain also regulates and manages voluntary motor actions.

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