Do we really have three brains?
You have probably heard that our brain is divided into three parts: the reptilian brain, the limbic system, and the cerebral cortex. This idea was proposed by Paul MacLean in the 1960s and is known as the triune brain theory. However, although this classification can help us understand how certain structures work, we now know that the brain does not work separately, but as a whole.
The brain as a global system
Before discussing the three parts of the brain, it is important to understand that they are all connected. The brain works like an orchestra, where each section has a distinct role, but all of them work together to generate thoughts, emotions, and behaviors.
The triune brain theory is still useful because it helps us better visualize which functions certain brain regions perform, although scientists today have confirmed that these structures do not act independently, but rather in an interconnected way.
The three brain structures according to MacLean
1. The reptilian brain: the basis of survival
This is the oldest level of the brain, responsible for basic functions such as breathing, sleep regulation, and instinctive responses. It is located in the brainstem and cerebellum, and controls automatic actions such as the reflex of pulling your hand away when you touch something hot.
Example: When you feel hungry and look for food, it is your reptilian brain activating to ensure your survival.
2. The limbic system: the emotional brain
Located above the reptilian brain, the limbic system is responsible for processing emotions and creating memories. Here we find structures such as the amygdala, which regulates fear and the response to danger, and the hippocampus, key to memory and learning.
Example: If a song has ever reminded you of a specific moment in your life, it is because your limbic system is associating the music with emotions and memories.
3. The cerebral cortex: the seat of thought and creativity
The most recent and evolved part of the brain is the cerebral cortex, responsible for logical thinking, planning, and language. This is where complex processes such as decision-making and creativity take place. Its development has allowed humans to invent, solve problems, and communicate.
Example: When you plan your week and organize your activities, you are using your prefrontal cortex to manage time and prioritize tasks.
The brain works as a whole.
Although this theory divides the brain into three levels, it does not mean they work separately. All areas are in constant communication. For example:
- If you see a snake (cerebral cortex), your limbic system processes the fear and triggers a flight reaction (reptilian brain).
- When you make a rational decision, the amygdala can influence it depending on the emotion you feel at that moment.
Current neuroscience has shown that there is no “emotional brain” isolated from a “rational brain”, but rather that both interact and affect each other.
Conclusion: a useful theory, but with nuances
The triune brain theory is a useful way to explain how different brain areas perform different functions, but we now know that the brain is an interconnected network that works as a whole. Understanding this helps us improve our decision-making, our emotional management, and our learning ability.
How can you apply this knowledge in your daily life? What strategies could you use to balance emotion and reason in your everyday life?
Sources
- MacLean, P. D. (1990). The Triune Brain in Evolution: Role in Paleocerebral Functions. Springer Science & Business Media.
- LeDoux, J. E. (2012). Rethinking the Emotional Brain. Neuron, 73(4), 653-676.
- Pessoa, L. (2017). Cognitive-Emotional Interactions: A Dynamic Perspective. Emotion Review, 9(3), 233-239.