The model of the 3 brains: reptilian, limbic and neocortex.

The three types of brain according to MacLean: what is the function of each of them?

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

The triune brain of Paul MacLeansometimes referred to as the 3-brain theory, has been very popular for years for grouping various regions of the brain into different sets that, according to this neuroscientist, 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 triune brain

Paul MacLean's idea of the triple brain is based on the idea that there are three distinct brain systems in the human brain. three distinct brain systems inhabit the human brain, each with its own logic of functioning.Each of them has been appearing in our evolutionary line in a sequential way, one on top of the other. This means, among other things, that these three brains would be relatively independent and that they would relate to each other following a hierarchy, depending on their age and the importance of their functions for our survival.

The reptilian complex, for example, being the first to appear, would be the structure that carries out the most basic and most important functions for survival in the here and now, while the neocortex, being the most recent structure to appear in the evolutionary line leading up to Homo sapiens, would be the one in charge of the most refined and complex functions.

The logic behind this conception of the human brain is very reminiscent of a way of understanding evolution as a process whereby the new accumulates over the old, so that these two parts maintain a relative independence of each other, although they affect each other.The logic of this conception of the human brain is very reminiscent of a way of understanding evolution as a process in which the new accumulates over the old, so that these two parts maintain a relative independence from each other, although they affect each other. It is also reminiscent of the idea that the emotional and the rational are part of two diametrically opposed psychological dimensions, and that where there is one there is no room for the other.

The parts of the brain according to Paul MacLean

Now that we have gone over the ideas on which the triune brain model is based, let's look at its parts separately:

1. The reptilian brain

For Paul MacLean the concept of the reptilian complex served to define the lowest area of the forebrain.The basal ganglia, where the so-called basal ganglia are located, and also areas of the brainstem and cerebellum responsible for the maintenance of the functions necessary for immediate survival. According to MacLean, these areas were related to the stereotyped and predictable behaviors that according to him define low evolved vertebrate animals, such as reptiles.

This structure would be limited to making simple and impulsive behaviors appear, similar to rituals that are always repeated in the same way, depending on the physiological states of the organism: 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 met.

2. The limbic brain

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

Its usefulness has to do with learning. If a behavior produces pleasant emotions, we will tend to repeat it or try to change our environment so that it occurs again, while if it produces Pain we will remember that experience and avoid having to experience it again. Thus, this component would play a fundamental role in processes such as classical conditioning or operant conditioning.

3. The neocortex

For MacLean the neocortex was the most recent evolutionary milestone in the development of our brain.. In this complex structure lay the capacity to learn all the nuances of reality and to draw up the most complicated and original plans and strategies. If the reptilian complex was based on the repetition of processes entirely by biology itself, the neocortex was permeable to all kinds of subtleties coming from the environment and from the analysis of our own actions.

For this neuroscientist, the neocortex could be considered as the seat of rationality in our nervous systemFor this neuroscientist, the neocortex could be considered the seat of rationality in our nervous system, since it allows the emergence of systematic and logical thinking, which exists independently of emotions and behaviors programmed by our genetics.

The three-brain model and marketing

The idea that we have a reptilian, a limbic and a rational brain has long seduced many people involved in the world of advertising, market research and marketing. The triune model makes it possible to consider separately three areas of people's psychological life that are very easy to learn and internalize: a rational, an emotional and an impulsive instance.

This has meant that in recent decades the focus of advertising campaigns has been on appealing to the reptilian and limbic brain, but not to the rational one: the reason is that, as these two are considered to be more deeply rooted in our evolutionary history, they are easier to predict and, at the same time, produce more powerful purchasing needs, given their importance and their hierarchical position as more important parts of the brain than the neocortex. Advertisements and marketing campaigns have shifted from thinking of the customer as an agent who needs to be informed about the product's features in order to decide rationally according to his interests, to trying to touch people's heartstrings to sell them a sensation associated with the product, rather than the product itself.

And the truth is that this change of approach is considered a great success; unlike in the 1960s, today it is very common to try to seduce potential buyers without talking about the product's features or its price: we simply evoke emotions or tell stories easily associated with a lifestyle we want to make our own. Ignoring the logic of the rational brain and focusing on emotions and basic desires is proving so profitable that even expensive products such as perfumes and cars are promoted in this way.

MacLean's theory in neuroscience, today

However, beyond what is happening in the business world, in neuroscience and in evolutionary biology the three-brain model is considered to be outdated, among other things, because it understands the three-brain model to beAmong other things, because it understands the development of the brain as a process of construction by "pieces" that have been assembled one on top of the other and that perform certain tasks by themselves. Today, the opposite is believed to be true: that in the functioning of the brain, it is not so much the function performed by the parts of the brain on their own that matters, but the way in which they are connected to each other to work together in real time.

Moreover, as far as we know, evolution does not cause new components to be integrated over the old ones, just as they are, without altering them. Every time a mutation causes a trait to become generalized, it alters the functioning of the organism as a whole, it alters the functioning of the organism as a whole and the way in which the parts that had evolved before function, it does not simply "expand" capabilities. That is why the idea that brain organs "in charge of the rational" are coupled over the previous ones has not been well accepted.

Moreover, the functions supposedly performed by each of the three brains well define the characteristic behavior of the groups of animals that, according to him, represent the moment of evolution in which these structures appeared. On the other hand, we now know that the basal ganglia (which would be part of the reptilian brain) are not involved in the execution of genetically programmed actions, but are associated with the performance of voluntary movements that, after much practice, have become automatic, such as riding a bicycle.