The Science of Trauma: How the Brain Responds

When we think about trauma or stress and how it affects us, it’s important to understand that our brains are composed of different "layers", each with its own functions and responses. These layers, often described as the reptilian brain, the mammalian brain, and the cerebral cortex, work together in complex ways that can influence how we react to stressful or traumatic events. Let’s explore each of these layers and see how they interact, especially in the context of trauma.

The Reptilian Brain: Our Most Ancient Wiring

The reptilian brain is the most ancient part of our brain, dating back to our evolutionary ancestors. This area includes the:

• brain stem
• cerebellum
• basal ganglia

It’s responsible for our most basic survival functions. Think of it as the autopilot of the brain, controlling essential processes like breathing, blood flow, and heartbeat.

When faced with danger or stress, the reptilian brain kicks in to ensure our survival. It doesn’t think or feel; it simply reacts. For example, if you suddenly hear a loud noise, your heart might start racing before you even have time to think about what caused the sound. This is your reptilian brain in action, automatically preparing your body for whatever might come next.

The Mammalian Brain: Our Emotional Center

The next “layer” is the mammalian brain, also known as the emotional brain or limbic system.

This area includes structures like the:

• thalamus
• hypothalamus
• amygdala
• hippocampus

These structures are heavily involved in memory and emotions.

The limbic system is particularly important because it connects our emotional responses to the more basic functions controlled by the reptilian brain. This is where our fight, flight, or freeze responses are generated. When we experience something emotionally charged—like fear or anger—the limbic system can trigger the reptilian brain to respond, leading to physical symptoms like a racing heart or a surge of adrenaline.

The Cerebral Cortex: The Seat of Higher Thinking

The cerebral cortex is the newest and most evolved part of our brain. This is where our higher-level thinking occurs—planning, organization, and language processing all happen here.

Unlike the reptilian and mammalian brains, the cerebral cortex allows us to think critically and make complex decisions.

How These Layers Interact: Real-Life Examples

Understanding how these layers work together can help us see why we react the way we do in stressful situations. Here are a few examples:

The Mammalian Brain Activating the Reptilian Brain

Imagine you’re feeling anxious about something—your limbic system detects this emotional state and sends signals to the reptilian brain. As a result, your heart starts to beat faster.

Emotion --> Physiological Response

The Cerebral Cortex Impacting the Mammalian Brain

While watching the news, your cerebral cortex processes the information and triggers an emotional response. This, in turn, activates the limbic system, making you feel stressed or upset.

Thoughts --> Emotion

The Cerebral Cortex Impacting the Reptilian Brain

You’re thinking about a big presentation at work. Your cerebral cortex anticipates the event, and even though nothing is happening yet, it signals your reptilian brain to start the stress response—your heart rate increases, and your body prepares as if it were already in the stressful situation.

Thoughts --> Physiological Response

The Reptilian Brain Impacting the Cerebral Cortex

If you’re really hungry, your reptilian brain’s basic survival instincts kick in, making it hard for you to concentrate on work. The need to eat makes it harder for you to focus on your tasks.

Physiological Response --> Thoughts

The Interconnectedness of Our Brain Layers

These examples illustrate how deeply interconnected our brain layers are, with the reptilian brain, mammalian brain, and cerebral cortex constantly communicating to shape our thoughts, emotions, and behaviors. This dynamic interplay is especially important when we face trauma or stress.

When we experience a traumatic event or stressful situation, our brain’s response isn’t just a simple reaction from one area. Instead, it involves a complex interaction between our survival instincts, emotions, and higher reasoning. Understanding this can help us see why certain situations trigger strong emotional and physical responses.

An Actionable Step You Can Take Today

When you notice physical reactions like a racing heart or sweaty palms, pause and connect these sensations to the thoughts you’re having. For example, if you realize your body is reacting to a stressful thought, acknowledge it: “I hear you, but I’m choosing a different thought.” This thought work helps you reframe your experience and regain control over your emotional and physical state.

Recognizing that our reactions are rooted in the brain’s intricate wiring allows us to shift our perspective. Instead of viewing these responses as something wrong with us, we can see them as our brain’s way of trying to protect us. This understanding empowers us to develop more effective coping strategies and become more attuned to the signals our body sends, so we can intervene before stress or emotion overwhelms us.