The 3 brains model: reptilian, limbic and neocortex

The human brain is the most complex system known. This means that, if you want to understand how it works, you have to find patterns and regularities in how it works and how it is structured; in other words, it is necessary to try to formulate useful and simple explanations about this set of organs.

Paul MacLean’s Trinitarian Brain, Which is sometimes known as the 3-brain theory, has been very popular for years for grouping multiple regions of the brain into different sets which, as this neuroscientist proposed, perform different tasks. The differentiated structures would be, according to MacLean, the reptilian complex, the limbic system and the neocortex.

Understanding the idea of ​​the Trinitarian brain

Paul MacLean’s idea of ​​the triple brain is based on the idea that in the human brain live three different brain systems, With their own operating logics, and that each of them appeared in our evolutionary line sequentially, on top of each other. This means, among other things, that these three brains would be relatively independent and would be linked to each other in a hierarchy, depending on their age and the importance of their functions in relation to our survival.

The reptilian complex, for example, being the first to appear would be the structure that performs the most basic and important functions to survive in the here and now, while the neocortex, being the most recent appearing structure in the evolutionary lineage leading to Homo sapiens, would be the one in charge of the most refined and complex functions.

The logic that follows this conception of the human brain is very reminiscent of a way of understanding evolution as a process in which the new builds up on the old, So that these two parts maintain a relative independence from each other, although they influence each other. It also recalls the idea that the emotional and the rational are part of two diametrically opposed psychological dimensions, and that where one is not vis-à-vis the other.

Parts of the brain according to Paul MacLean

Now that we’ve gone through the ideas that the Trinitarian Brain Model is based on, let’s look at its parts separately:

1. The reptilian brain

For Paul MacLean, the concept of reptilian complex was used to define the lowest zone of the forebrain, Where the so-called basal ganglia are located, as well as areas of the brainstem and cerebellum responsible for maintaining the functions necessary for immediate survival. These areas, according to MacLean, were linked to the stereotypical and predictable behaviors that he said define poorly evolved vertebrate animals, such as reptiles.

This structure would be limited to revealing simple and impulsive behaviors, similar to rituals that are always repeated in the same way, depending on the physiological states of the body: fear, hunger, anger, etc. It can be understood as a part of the nervous system that is limited to executing genetically programmed codes when the right conditions are given.

2. The limbic brain

The limbic system, which according to MacLean appeared with the most primitive mammals and based on the reptilian complex, was presented as a structure responsible for the appearance of the emotions associated with each of the experiences.

Its usefulness is linked to learning. If a behavior produces pleasant emotions, we will tend to repeat it or try to change our environment so that it happens again, while if it hurts, we will remember the experience and avoid having it again. Thus, this component would play a key role in processes such as classical conditioning or operant conditioning.

3. The neo-crust

For MacLean, the neocortex was the most recent evolutionary milestone in our brain’s development. In this complex structure lies the ability to learn all the nuances of reality and to draw the most complicated and original plans and strategies. While the reptilian complex relied on the repetition of processes entirely by biology itself, the neocortex was permeable to all manner of subtleties of the environment and the analysis of our own actions.

For this neuroscientist, the neoscort could be considered as the seat of rationality in our nervous systemBecause it allows us the emergence of a systematic and logical thought, which exists independently of the emotions and behaviors programmed by our genetics.

The three-brain model and marketing

The idea that we have a reptilian, limbic, rational brain has long appealed to many people engaged in advertising, market research, and marketing. The Trinitarian model allows us to consider separately three areas of people’s psychological life which are very easy to learn and internalize: a rational instance, an emotional instance and an impulsive instance.

This means that in recent decades, interest in advertising campaigns has focused on appealing to the reptilian and limbic brain, but not to the rational: the reason is that, given that these two are more rooted in our evolutionary history, are easier to predict, and at the same time produce more powerful purchasing needs, given their importance and hierarchical position as parts of the brain more important than the neocortex. Advertisements and marketing campaigns have shifted from thinking of the customer as an agent who needs to be informed about the characteristics of the product to making a rational decision according to his interests of trying to reach the sensitive fiber of people to sell them a sentiment associated with the product, rather than the product itself.

And the truth is that this change of approach is considered a great success; Unlike the 1960s, today it is very common to try to seduce potential buyers without talking about the characteristics of the product or its price: simply evoking emotions or telling stories easily associated with a lifestyle that one wants to make ours. Switching to rational brain functioning logics and targeting basic emotions and desires is proving so profitable that even products as expensive as perfumes or cars are promoted.

MacLean’s theory in neuroscience today

However, beyond what is happening in business, neuroscience and evolutionary biology the three-brain model is considered outdated, Among other things, because it understands brain development as a process of building by “pieces” that have been assembled on top of each other and performing certain tasks by themselves. Today, it is believed the opposite: in the functioning of the brain, it does not matter what function certain parts of the brain perform on their own than how they connect to each other to work together and in real time.

Moreover, to our knowledge, evolution does not involve the integration of new components compared to the old ones, as such, without altering them. Whenever a mutation causes the generalization of a trait, it affects the functioning of the body as a whole and how the parts that evolved before the job were not limited to “expanding” capabilities. This is why the idea that the brain organs “responsible for the rational” are coupled to the above has not been well accepted.

Moreover, the functions that each of the three brains would have performed well define the characteristic behavior of the groups of animals which, according to him, represent the moment of evolution at which these structures appeared. On the other hand, we know today that the basal ganglia (which would be part of the reptilian brain) have nothing to do with the execution of genetically programmed actions, but are associated with the execution of voluntary movements only after “ having been widely practiced ”, they have become automatic, like cycling.

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