The largest part of the brain and closest to the surface is the Cortex. This is often divided into lobes: the Frontal lobe, the Occipital lobe, the Parietal lobe, and the Temporal lobe. The Frontal lobe is located at the front of the head and is in charge of organisation, planning, reasoning and controlling emotions. It is also called the the "rational brain" or the "upper brain".
At the centre of the brain we find the Amygdala, a group of cells that interprets the emotional meaning of everything that happens to us. When it perceives something as threatening, it sends messages to another structure, the Hypothalamus, which controls the release of hormones in the body to prime the body for a response. The fight-or-flight response occurs when our body tenses up, becomes more alert, and is ready to act to either flee or defend itself. Another structure, the Hippocampus, organises memories so the Amygdala can interpret an event. These three structures are part of what we call the "emotional brain" or "lower brain". This part of the brain can sometimes overreact and then needs the help of the frontal lobe, the rational brain, to calm down.
But how do these parts interact with each other?
The lower brain is the part of our brain that lets us act without thinking. In a life-threatening situation, there is no time to sit down and think about a plan of action. This part of the brain is well developed at birth and forms more connections earlier than the upper brain because it is responsible for important tasks such as meeting our needs, feeling strong emotions, using our instincts to keep us safe, and controlling bodily functions.
The rational upper brain is structurally complete, but its connections develop much more slowly. This part of the brain is highly developed and responsible for problem solving, rational thinking, logic, planning, decision making, organisation and self control. All of these things are learned through repeated experience. During puberty, the top level of the brain is rebuilt, which takes a few more years. So the upper brain is not fully mature until the mid-twenties.
Despite the different development of the parts, there are strong connections between the upper and lower parts of the brain through which information is exchanged. In our brain, these connections are not obvious, but they work in a productive way. We need the lower emotional brain to inform the upper rational brain with instincts and reflexes, feelings and information about our bodily functions such as breathing, temperature and so on. But we also need upper brain messages to moderate and understand the information coming from below.
"The human brain is an incredible pattern-matching machine."
– Jeff Bezos
Most kids function primarily with the emotional, reactive lower brain – throwing a tantrum over being given the wrong colour plate and being afraid to put their face under water in swim class. Their rational, self-controlling brain has yet to learn how to deal with such situations, and the connections between the upper and lower parts are blocked by the emotional overload, allowing very little problem-solving and effective decision-making.
When we, as parents, know that there are parts of our children's brains that are underdeveloped, we can respond to their feelings and behaviour in ways that support them and help them build connections in their brains based on positive experiences, instead of punishing and shutting them down.
This means that the communications in the brain are not only crucial for our own everyday decisions, but also important for dealing with children.
And yet our own brain is only fully developed in our mid-twenties.