The way our brains process trauma has become clearer in recent decades, and these discoveries have reshaped trauma psychology. Neuroscience now shows how different brain areas interact, highlighting pathways that help us process, respond to, and recover from trauma. A key framework, developed by Yale neuroscientist Paul MacLean, is the "triune brain" model, which divides the brain into three parts: the reptilian brain, the mammalian brain, and the cerebral cortex. This triune model reveals how each section of our brain works together, particularly when we face trauma or intense stress. In this post, we'll dive into each part of the triune brain, breaking down its roles in our reactions, emotional processing, and resilience.
The Reptilian Brain: Managing Basic Functions and Instincts
The oldest part of the brain, the reptilian brain, is essential for survival. Located at the brain's base, it controls basic, involuntary functions. It encompasses areas like the brainstem, cerebellum, and basal ganglia, which work together to regulate functions like breathing, digestion, and muscle memory. While these actions may seem simple, they're actually foundational to how we cope with trauma.
For example, the brainstem keeps essential functions like breathing and blood pressure steady, even under stress. The cerebellum helps with coordination and balance, supporting us as we physically react to threats. Meanwhile, the basal ganglia, often known as the reward center, links to our habits and learned behaviours. When we experience trauma, these "automatic" functions and routines help us survive and respond quickly, giving our body the best chance to stay safe.
The Mammalian Brain: Emotional Reactions and Trauma Responses
The mammalian brain, or limbic system, is where our emotions and social attachments reside. Positioned in the midbrain, this area is essential for processing feelings and plays a significant role in our typical trauma responses. The limbic system includes structures like the thalamus, hypothalamus, amygdala, and hippocampus, each contributing to our emotional experiences and survival instincts.
The amygdala, often called the brain's "fear center," is especially critical in trauma responses. It assesses information from the senses, determining whether a stimulus is safe or dangerous. If a threat is perceived, the amygdala sends signals to the hypothalamus, which releases stress hormones like cortisol and adrenaline. These hormones trigger fight, flight, freeze, or fawn responses to help us react to danger.
The hippocampus, which sits near the amygdala, organizes these emotional memories, helping to place experiences into context. In trauma, however, the hippocampus may struggle to accurately catalogue details, which can result in fragmented memories of the traumatic event. These memories, known as implicit memories, are powerful and can be triggered by similar sights, sounds, or feelings, reactivating the trauma response.
The Cerebral Cortex: Higher Thinking and Emotional Regulation
The cerebral cortex, often referred to as the thinking brain, represents the most advanced level of brain function. This area houses the prefrontal cortex and divides into the right and left hemispheres, each supporting different types of thinking and communication. The right hemisphere is more involved in emotions, nonverbal communication, and processing negative emotions. The left hemisphere, by contrast, focuses on language, logical thinking, and organizing life events into a coherent narrative.
Within the cerebral cortex, the dorsolateral prefrontal cortex handles working memory, decision-making, and insight. Meanwhile, the medial prefrontal cortex plays a vital role in regulating emotions and controlling impulses. It works closely with the limbic system, especially the amygdala and hippocampus, to create a complete picture of emotional experiences and store them as explicit memories.
When trauma activates the limbic system, however, the cerebral cortex often gets "overruled," making it difficult to think clearly or regulate emotions. This is the reason behind the feeling of “flipping out” during intense emotional experiences—the rational parts of the brain can’t intervene effectively, and we're left in a reactive, survival-oriented state.
How the Triune Brain Affects Trauma and Healing
In a traumatic situation, the triune brain coordinates a complex sequence of reactions. First, sensory information enters through our senses and reaches the thalamus, where the amygdala assesses whether the situation is safe or dangerous. If danger is detected, the hypothalamus releases stress hormones, activating the body’s response to cope with the threat. This sequence can keep us safe in the short term but also creates strong, implicit memories of the event.
These memories include not only visual snapshots but also emotions, bodily sensations, and beliefs formed during the trauma. If, later, we encounter a situation that feels similar, it can re-trigger the fight, flight, freeze, or fawn response. Over time, these reactive patterns can persist, keeping the brain on high alert and limiting our ability to process experiences rationally.
Healing from trauma often involves helping the brain integrate these implicit memories into explicit memories. By consciously processing and contextualizing traumatic events, the cerebral cortex can gradually create a complete narrative, giving us a sense of control and understanding. Many therapeutic interventions focus on this goal, aiming to strengthen the cerebral cortex’s role in regulating and calming the limbic system. Techniques like mindfulness, cognitive behavioural therapy, dialectic behavioural therapy, and EMDR (Eye Movement Desensitization and Reprocessing) help bridge this gap, allowing the brain to move traumatic memories from an emotionally reactive place to a calm, integrated memory.
The Path to Healing: Why Understanding the Brain Matters
Understanding the triune brain can help demystify trauma responses, offering a clearer path toward healing. When we know that the reptilian brain is at work, we can better understand those gut-level reactions. When we feel the limbic system taking over, we recognize it’s our brain's way of trying to keep us safe. By strengthening the cerebral cortex, we can regain control, integrating traumatic memories into a cohesive story that empowers us rather than triggers us.
Trauma impacts every part of the brain, but healing is possible. By exploring and balancing each layer of the triune brain, trauma recovery becomes a holistic process. Therapies aimed at regulating the emotional brain and strengthening the thinking brain offers hope for integrating painful memories and fostering resilience. As the field of psychology continues to grow, so do our resources for supporting trauma recovery, helping individuals move from reaction to resilience and reclaiming their lives.
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