How Stress Wires the Brain: Understanding Neurodevelopment & Nervous System Regulation
The human brain is a highly organized system designed to respond, adapt, and evolve based on experiences. Understanding how the brain develops—from the bottom up—reveals why early life experiences, stress, and nervous system regulation play such a crucial role in long-term health, behavior, and learning.
How the Brain Develops: Bottom-Up Organization
The brain is not fully developed at birth—it follows a specific developmental sequence from the most primitive survival functions to the highest-level thinking and decision-making processes. This bottom-up approach means that early stress, trauma, and nervous system dysregulation can significantly impact a child’s ability to regulate emotions, process information, and interact with the world.
1️⃣ Brainstem (Survival & Reflexes) – Birth to Age 1 – This is the first area to develop and is responsible for autonomic functions like breathing, sleep, and heart rate. It receives sensory input and determines basic survival responses like fight, flight, or freeze.
2️⃣ Limbic System (Emotions & Memory) – Ages 1-6 – This area develops next, governing emotions, attachment, and meaning-making. It determines whether an experience is safe or threatening and influences stress hormone responses. At this stage, children lack a fully developed prefrontal cortex, which means they do not differentiate between imagination and reality. This is why movies, video games, and fictional stories can deeply impact their emotional state and even cause confusion about what is real.
3️⃣ Cortex & Prefrontal Cortex (Executive Function & Higher Thinking) – Ages 6-25 – This is the last area to mature, responsible for critical thinking, decision-making, problem-solving, and emotional regulation. The prefrontal cortex relies on input from lower brain centers and must have a regulated nervous system foundation to function optimally. Full maturation occurs in the mid-20s, which is why children and teenagers often struggle with impulse control, emotional regulation, and long-term planning.
🚨 Key Insight: If early brain development is shaped by chronic stress, fight-or-flight responses, or a lack of safety, the higher brain functions may not fully develop, leading to challenges with learning, behavior, and emotional control.
The Nervous System: The Operating System of the Brain
The nervous system is the command center of every function in the body. It determines how we interpret the world, respond to stress, and regulate emotions. A well-regulated nervous system is flexible and resilient, able to shift between states of safety, engagement, and necessary stress responses. However, when stress overwhelms the system, it can become stuck in protective modes, affecting brain function and long-term health.
✔ Neuroception – The nervous system's subconscious ability to scan the environment for safety, danger, or life threat. This process happens below our conscious awareness and dictates how we react to people, situations, and stress. If neuroception detects danger—whether real or perceived—it will trigger the body's survival mechanisms.
✔ Subcortical Response – Unlike conscious memories stored in the cortex, early stress is encoded in the hindbrain and midbrain, meaning that trauma is not always a memory—it is often a physiological reaction. This explains why certain sounds, environments, or interactions can trigger strong emotional or physical responses without conscious understanding.
✔ Three Modes of Operation:
Ventral Vagal (Safe & Social) – The ideal state for learning, connection, and healing. In this state, a person feels calm, engaged, creative, and emotionally present. The body can properly regulate digestion, immune function, and cognitive processes.
Sympathetic (Fight or Flight) – This mode prepares the body to react to threats by increasing alertness, heart rate, and stress hormones. While necessary for motivation and physical engagement (exercise, productivity), chronic activation leads to anxiety, hypervigilance, and difficulty relaxing.
Dorsal Vagal (Shutdown & Freeze) – When stress becomes overwhelming or inescapable, the body shifts into protective conservation mode. This can manifest as disconnection, numbness, chronic fatigue, low motivation, or dissociation.
A healthy nervous system should be able to move between these states as needed, but chronic stress, trauma, and environmental factors can cause long-term wiring into survival-based patterns, making it difficult to return to a regulated state.
The 3 T’s: How Stress Wires the Nervous System
Chronic stress can shape the developing brain, wiring it toward hypervigilance, withdrawal, or poor adaptability. The Three T’s—Thoughts, Traumas, and Toxins—are key factors that influence this wiring.
✔️ Thoughts (Emotional Stress) – Chronic worry, fear, overstimulation, and the fast-paced, over-scheduled nature of modern life create ongoing sympathetic activation, making it harder to relax and recover. Constant exposure to technology, social media, and digital overload also places additional stress on the nervous system, leading to increased anxiety and decreased emotional regulation. ✔️ Traumas (Physical Stress) – Birth trauma, falls, poor posture, or injuries affect nervous system regulation, keeping the body in a stress response. ✔️ Toxins (Chemical Stress) – Processed foods, environmental toxins, and medications can overload the system, impairing digestion, energy, and cognitive function.
Each of these stressors can wire the nervous system into an altered state, making it difficult to transition between modes fluidly.
Conclusion: Supporting the Developing Brain
Understanding brain development helps us see why early experiences, stress, and nervous system health play such a foundational role in lifelong health and function. By supporting nervous system regulation, chiropractic care helps optimize brain function, allowing children and adults to adapt, learn, and thrive.
📅 If you or your child struggle with emotional regulation, sensory issues, or nervous system imbalances, schedule a consultation today to see how chiropractic care can support optimal brain development.
