Physiology of the brain. Triune structure of the brain.

Paul McLean's idea of the triple brain is based on the idea that 3 different brain systems inhabit the human brain, with their own logic of operation, and that each of them appears sequentially in our evolutionary line above one another. This means, among other things, that these three brains would be relatively independent, and that they would be linked in a hierarchy, depending on their age and the importance of their functions to our survival.

For example, the reptilian complex, appearing first, will be the structure that performs the most basic and essential functions for survival here and now, while the neocortex is the newest structure in the evolutionary line that leads to Homo sapiens, responsible for the most sophisticated and complex functions.

The logic that follows this conception of the human brain closely resembles the way evolution is understood as a process in which the new builds upon the old, so that the two parts maintain a relative independence from each other even though they influence each other. It also brings to mind the idea that the emotional and the rational are part of two diametrically opposed psychological dimensions, and that where one is present, the other does not fit.

Now that we've reviewed the ideas behind the triune model of the brain, let's look at its parts individually:

For Paul McLean, the concept of the reptilian complex served to identify the lowest part 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. According to McLean, these zones were associated with stereotyped and predictable behavior, which he believes defines less evolved vertebrates such as reptiles.

This structure will be limited by the appearance of simple and impulsive forms of behavior, similar to rituals, which are always repeated in the same way, depending on the physiological states of the body: fear, hunger, anger, etc. This can be understood as a part of the nervous system that is limited to carrying out genetically programmed codes when given the right conditions.

Reptilian brain - is responsible for sensory-motor reactions (the work of 5 senses, with the help of which we perceive the material world). It is located in the central and posterior part of the brain, consisting of the stem and the cerebellum. Its structure resembles the brain of a reptile. The reptilian brain is responsible for: breathing, heartbeat, digestion, movement, balance, reproduction, protection of one's territory, the desire to own everything and control everything.

The functions of the reptilian brain are quite simple: "run - defend - freeze."

The task of the reptilian brain is to protect the body, accompanied by automatic reactions. This part of the brain is responsible for the safety of the species and is always "on guard", so the perception of the surrounding world is through the prism of negativity, which consists of dangers and threats. The survival instinct is embedded in the reptilian brain, for the sake of procreation.

In the process of evolution, the reptilian brain grew new areas and brain structures on top of itself, namely the mammalian brain (limbic brain).

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

Its usefulness is related to learning. If a behavior causes pleasant emotions, we tend to repeat it or try to change our environment so that it occurs again, whereas if it causes pain, we will remember the experience and avoid experiencing it again. Thus, this component would play a fundamental role in processes such as classical conditioning or operant conditioning.

Limbic brain – responsible for sensation, experience, biorhythm control, memory and learning, controls blood pressure, heart rate, metabolism, hunger, immune system status and sleep. The limbic brain receives information from the reptilian brain, processes it and records it in memory, it is the main generator of emotions: sadness, anger, joy, fear, curiosity, disgust, etc.

The limbic brain gives an emotional color to an emotional experience, what was pleasant - promotes repetition, what is negative - leads to rejection or avoidance. In union with the reptilian brain, they transfer lessons from past experiences to the present moment

The emotional brain connects all memories from the past as if they are happening now and are experienced as real. There is a strong connection between memory and emotion through memories. This is explained by the fact that a person develops a certain behavior for certain situations. After all, the task of the emotional brain is to help a person to be in the comfort zone, and leaving the comfort zone leads to the fact that the brain gets stressed.

It's no secret that in a state of stress we experience a flood of negative feelings, which can later affect our mental state. Therefore, the formation of avoidance behavior will be a very effective mechanism. Why does a person have extra negative emotions?

It is important to remember when resistance to change is felt, to understand that the emotional brain has taken over. Disturbances in the functioning of the limbic system explain excessive vulnerability and anxiety, attacks of rage, fear and aggression in humans. The reptilian brain protects our body from physical threats, and the limbic system from emotional threats.

For MacLean, the neocortex was the final evolutionary milestone in the development of our brain. In this complex structure, the ability to learn all the nuances of reality and to make the most complex and original plans and strategies was preserved. If the reptilian complex was based on the repetition of processes completely by biology itself, then the neocortex was permeable to all kinds of subtleties from the environment and analysis of our own actions.

For this neuroscientist, the neocortex can be considered the seat of rationality in our nervous system because it allows us to produce systematic and logical thinking that exists independently of our genetically programmed emotions and behaviors.

Thinking brain (neocortex, cerebral cortex) – is responsible for decision-making, thinking, situation analysis, appropriate management of motor reactions, planning, analysis of messages received from the senses, realization of creative abilities, building an image of the surrounding world, the ability to read information from the surrounding world, the development of oral and written speech, the development of imagination, planning for the future, setting goals.

A great advantage of the thinking brain is our thoughts, which are formed through language.

The most important achievement of evolution is that man has the ability to predict his future and realize abstract concepts - the passage of time.

If my actions are like this, then I will get this, if I move like this - then the result will be like this. (N: If I speak different languages, more opportunities will open up; if I betray my friend, the trusting relationship will be broken) It is important to remember that a child comes into the world with a reptilian and emotional brain, the thinking brain begins to develop from the moment language learning

When we talk about changing the structure of the brain, we mean the structure of neural connections. Any of our habits is a certain connection of neurons, and as the habit is repeated, this connection becomes stronger. Beliefs that limit and are nothing more than a "habit" of thinking in a certain way can also be included there.

Thoughts can change our brain, rebuild neurons and synapses. The language of the brain is the electrochemical messages that are transmitted through axons and activate neurons. These messages are the result of both physical actions and mental processes. The brain encodes both in the same way.