From Reptilian Survival to Neomammalian Intellect: Journeying Through the Triune Brain
“Have you ever noticed these patterns in your everyday life?
We tend to give money to poor people at the door of a hotel after eating the food rather than before food.
We make very stupid decisions when we are stressed. There’s also a popular quote: ‘Don’t promise when you’re happy, Don’t reply when you’re angry, and don’t decide when you’re sad.’
We feel frightened even if we watch a video of a snake or other things that evoke fear.
These are some examples. Why do we behave like this?”
This can be explained a simple concept called Triune Brain or 3-layered brain theory. This theory was popularized by neuroscientist Paul D. MacLean in the 1960s and 1970s. The Triune Brain Theory suggests that the human brain consists of three major evolutionary components, each representing distinct stages of development:
Reptilian Brain (Brainstem/Lizard Brain): This is the oldest and most primitive part of the brain, responsible for essential survival functions such as breathing, heart rate, and basic instincts. It controls autonomic functions and is shared with other vertebrate animals.
Limbic System (Paleomammalian Brain): The limbic system is associated with emotions, memory, and motivation. It includes structures like the amygdala, hippocampus, and hypothalamus. This part of the brain is more developed in mammals and plays a significant role in emotional experiences and social behaviors.
Neocortex (Neomammalian Brain/Human Brain): The neocortex is the most recent and highly developed part of the brain in humans. It is responsible for advanced cognitive functions, such as conscious thought, language, reasoning, problem-solving, and complex decision-making. This part of the brain sets humans apart from other animals and is involved in higher-order processing.
These are the 3 different layers of brain. Now we will see different type of communications between layers.
Limbic layer to Reptilian Brain:
Threat Response: When the limbic brain perceives a potential threat or danger, such as seeing a predator or encountering a hazardous situation, it activates the “fight-or-flight” response. This response involves the release of stress hormones like adrenaline and cortisol. The limbic brain then communicates with the reptilian brain (brainstem) to initiate the physiological changes needed for survival. The reptilian brain controls autonomic functions like increased heart rate, dilated pupils, and increased blood flow to muscles, preparing the body to either confront the threat or flee from it.
Emotional Regulation: The limbic brain, particularly the amygdala, plays a crucial role in processing emotions. When a situation triggers an emotional response, such as fear, joy, or anger, the limbic brain processes this information and communicates with the reptilian brain and other brain regions, including the neocortex. This communication allows for the integration of emotional experiences with other cognitive processes, helping to regulate and express emotions in a socially appropriate manner.
Social Behaviors: The limbic brain is also involved in social behaviors and interactions. It helps in recognizing facial expressions, understanding emotional cues from others, and forming social bonds. In situations where social connections are vital for survival, the limbic brain communicates with the reptilian brain to influence behaviors such as cooperation, empathy, and nurturing.
Homeostasis: The limbic brain, particularly the hypothalamus, is involved in maintaining internal balance or homeostasis in the body. It communicates with the reptilian brain to regulate functions like hunger, thirst, and body temperature, ensuring the body’s basic physiological needs are met.
Overall, the communication between the limbic brain and the reptilian brain is an integral part of the brain’s functioning, enabling the brain to respond to threats, process emotions, engage in social interactions, and maintain essential bodily functions. This intricate interplay between brain regions allows humans and other animals to adapt and survive in diverse environments and social contexts.
Neocortex to Reptilian Brain:
Executive Control: The neocortex, specifically the prefrontal cortex, is responsible for executive functions such as planning, reasoning, decision-making, and impulse control. When faced with a situation that requires a conscious response, the neocortex communicates with the reptilian brain to modulate instinctual or impulsive reactions. For example, if you encounter a dangerous situation, the neocortex may override an immediate fight-or-flight response and instead choose a more thoughtful and strategic approach to deal with the threat.
Emotional Regulation: The neocortex plays a crucial role in regulating emotions and tempering emotional responses generated by the limbic brain. When emotional stimuli are processed in the neocortex, it can exert top-down control over the emotional responses generated by the limbic system. This helps in adapting emotions to specific situations and behaving in socially acceptable ways.
Conscious Perception and Sensory Integration: Sensory information from the environment is processed in the neocortex, allowing for conscious perception and awareness. The neocortex then communicates with the reptilian brain to coordinate appropriate responses to the sensory inputs. For example, if you see and smell delicious food (sensory input), the neocortex might evaluate the situation and decide whether it’s safe to approach and eat the food (conscious perception), and then signal the reptilian brain to initiate the necessary digestive responses.
Learning and Memory: The neocortex is crucial for learning and memory formation. When you learn new information or acquire new skills, the neocortex processes and encodes this knowledge. Later, during memory recall or decision-making processes, the neocortex communicates with the reptilian brain to apply previously learned information to guide behaviors and responses to various situations.
Voluntary Motor Control: The neocortex is directly connected to the motor regions of the brain. When you decide to perform a voluntary action, such as picking up an object or walking, the neocortex sends signals to the reptilian brain (brainstem and spinal cord), which then coordinates the appropriate motor commands to execute the action.
The communication between the neocortex and the reptilian brain allows for the integration of higher cognitive functions with essential survival mechanisms, providing humans with the ability to make complex decisions, exhibit self-control, regulate emotions, and adapt to a wide range of situations in a purposeful and flexible manner.
Reptialian brain to neocortex
Sensory Input: The reptilian brain, which includes the brainstem and cerebellum, receives and processes sensory information from various parts of the body and the external environment. Sensory inputs related to touch, temperature, pain, vision, hearing, taste, and smell are first processed in the brainstem.
Basic Physiological Functions: The reptilian brain regulates and controls essential physiological functions critical for survival, such as heart rate, breathing, blood pressure, digestion, and body temperature. These functions are controlled by the autonomic nervous system, which includes both the sympathetic and parasympathetic divisions, and the reptilian brain plays a central role in this regulation.
Fight-or-Flight Response: When the reptilian brain detects potential threats or stressors in the environment, it activates the “fight-or-flight” response. This is an automatic physiological and behavioral reaction that prepares the body to either confront the threat or flee from it. The brainstem communicates with the neocortex to inform it of the perceived threat, triggering higher cognitive processes to assess the situation and decide on an appropriate response.
Conscious Awareness: While the reptilian brain is primarily responsible for regulating basic survival functions and processing sensory information, it also influences conscious awareness. For example, if you accidentally touch a hot stove, the sensory information about the pain is first processed in the brainstem, but your conscious awareness of the pain is then relayed to the neocortex, allowing you to recognize the danger and remove your hand.
Attention and Arousal: The brainstem is involved in regulating levels of alertness, arousal, and attention. It communicates with the neocortex to modulate cognitive functions based on the individual’s level of wakefulness and focus.
Overall, the communication from the reptilian brain to the neocortex forms the foundation for higher cognitive processes, allowing humans to be aware of their environment, respond to sensory inputs, and make decisions based on survival needs and bodily functions. This integration of information from the reptilian brain with higher brain regions is essential for adaptive behaviors and the overall functioning of the human brain.
Limbic brain to neocortex
Emotional Processing: The limbic system, which includes structures like the amygdala, hippocampus, and hypothalamus, is responsible for processing emotions and emotional memories. When something emotionally significant occurs, such as a pleasant or threatening event, the limbic system processes this information and generates emotional responses.
Memory and Learning: The hippocampus, a part of the limbic system, plays a crucial role in memory formation and learning. It consolidates information from short-term memory to long-term memory, allowing experiences and emotions to be stored and retrieved later.
Emotional Signaling: The limbic brain communicates with the neocortex to signal the presence of emotions. For example, if something evokes fear, the amygdala triggers the physiological and emotional components of fear, and this information is relayed to the neocortex, informing the individual of their emotional state.
Impact on Decision Making: Emotional information from the limbic brain influences decision-making processes in the neocortex. Emotions can bias judgments and influence choices, even in seemingly rational decision-making situations. The interaction between emotional experiences and cognitive processing in the neocortex helps individuals make decisions that align with their emotional states and goals.
Social Cognition: The limbic system also contributes to social cognition, enabling individuals to understand and respond to the emotions of others. This is essential for empathy, social bonding, and maintaining social relationships. The limbic brain’s communication with the neocortex allows for the interpretation of social cues and the regulation of emotional responses during social interactions.
Emotional Regulation: The prefrontal cortex, a part of the neocortex, plays a significant role in regulating emotions. It can exert top-down control over emotional responses generated by the limbic brain, helping to modulate emotional reactions and exhibit emotional intelligence in social situations.
Overall, the communication from the limbic brain to the neocortex is essential for integrating emotional experiences and social information with higher cognitive processes. This integration allows for conscious emotional awareness, adaptive decision-making, and the ability to navigate complex social interactions effectively.
Hope you have learned different communications between each layers. Now we can check the different situations i mentioned earlier and what are the communication evolved.
We are less charitable when we are hungry
Here in this situation our lizard brain communicating to neo-cortext brain that we need food donot think anything else 😀
Don’t make decision emotionally or under stress
In this case limbic brain more activated in this case so signalling to neocortex can we wrong. Because if we are too happy our neocortex recieves happy memories only and the viceversa.
If these cases our reasoning may not always correct
We become frightened even if saw snakes in videos
In this case neocortext communicate with limbic brain and produce same emotion as we saw it real. Once limbic brain is trigger it automatically trigger lizard/reptilian brain.
The Triune Brain theory can explain only in higher level. Our brain is more complicated than this.
Please share you thoughts on this 😀
References
https://bigthink.com/the-well/3-layers-of-the-brain/
https://en.wikipedia.org/wiki/Triune_brain
