Chapter 1: The Nature of Fear and Survival

Fear is an intrinsic part of being human. This emotion plays a crucial role in how we respond to threats in our environment. Let’s delve into the physiological responses that occur within our bodies during dangerous situations.

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Consider a scenario: you are trekking through a lush forest, enveloped by towering trees and the sounds of nature all around. Suddenly, a noise from the underbrush piques your interest. You glance over and see a large bear stepping out from behind the trees. In that instant, your body springs into action.

Your body reacts almost instantaneously. You begin to perspire, your heart races, and your breathing quickens. This is your body's natural defense mechanism kicking in.

Essentially, your system has activated its "defense mode." This response has been a subject of intrigue, especially with the advancements in research over recent decades.

When we encounter danger or even perceive a threat, our bodies enter a state of stress, triggering what is known as the “fight or flight” response (Cannon, 1927). As the name indicates, the body prepares to either confront the danger or flee from it. Interestingly, there is also a third response: the "freeze" mode, which typically occurs before the fight or flight response.

What causes this phenomenon?

Stress is the key trigger (Roseboom et al., 2007). Imagine stress as a powerful wave surging through your body, leading to a series of physiological changes. Common signs of this “freezing” response include muscle tension, accelerated breathing, reduced communication, a drop in body temperature, and a decrease in heart rate (Roelofs, 2017). These adaptations equip the body with the energy required to address or escape the threat (Roelofs & Dayan, 2022).

Why does the heart rate slow down?

The human circulatory system comprises arteries, which carry blood away from the heart, and veins, which return blood to it. Any imbalance in blood flow can lead to circulatory issues, which can be detrimental to health.

In high-stress scenarios, our blood vessels constrict, causing blood to circulate faster than usual, ensuring that our bodies receive adequate oxygen and nutrients for the crisis at hand (Lassen, 1959). This surge in blood flow creates pressure, stretching the vessel walls. Within these walls are sensitive nerve fibers, known as “baroreceptors,” which detect this pressure and send signals to the brain indicating, “The heart needs to slow down!”

Consequently, the blood vessels dilate, creating additional space for the circulating blood. This process leads to a slower heart rate and reduced pressure in the circulatory system (Duschek & Reyes del Paso, 2007).

This may help explain the sequence of heart rate changes during stressful moments: an initial increase followed by a rapid decrease (Adenauer et al., 2010; Roelofs, 2017; Roelofs & Dayan, 2022; Steptoe & Sawada, 1989).

During this critical period, an intriguing phenomenon occurs: previously, this was only observable in animals. When we closely observe a standing person, we can see slight shifts in their body position, akin to a pendulum’s motion. These subtle movements, known as “body oscillations,” become less pronounced or may even cease altogether when we feel threatened. This is termed “freezing” in scientific literature, signifying both the reduced body movement and the simultaneous slowing of the heart rate.

In laboratory settings, heart rate “freezing” is measured using electrodes attached to the heart, while body sway is monitored using a device known as a “balance board,” which is sensitive enough to detect minute changes in body position (Azevedo et al., 2005; Roelofs et al., 2010). Recent findings suggest that freezing may serve a critical role in preparing the body for future actions (Hashemi et al., 2019; Klaassen et al., 2021; Roelofs & Dayan, 2022). Studies indicate that individuals who exhibit freezing behavior tend to respond more swiftly and accurately (Gladwin et al., 2016; Hashemi et al., 2019).

Furthermore, evidence suggests that individuals with higher anxiety levels tend to freeze more than those with lower anxiety levels, while those with trauma may exhibit minimal freezing (Roelofs et al., 2010; Fragkaki et al., 2017). However, research into the relationship between freezing and mental health is still in its early stages.

The human body features a complex network of systems that adapt, communicate, and respond during threatening situations. The act of freezing, in particular, showcases its effectiveness during these moments. Rather than a passive response, it empowers us with the ability to react appropriately and navigate out of danger. This fascinating response warrants further exploration in future studies.

Chapter 2: The Science of Trauma and Its Effects

This insightful video, "What Trauma Does to Your Brain and Body" by Bessel van der Kolk, explores the profound impact trauma has on both our mental and physical health, shedding light on the intricate connections between our experiences and bodily responses.

Chapter 3: Differentiating Brain Responses to Threats

In the video "Understanding Trauma: Learning Brain vs Survival Brain," the distinctions between our learning brain and survival brain are examined, providing a deeper understanding of how we react to trauma and stress.

Literature

Cannon, W. B. (1927). The James-Lange theory of emotions: A critical examination and an alternative theory. American Journal of Psychology, 39, 106–124.

Lacey, B. C., & Lacey, J. I. (1970). Some autonomic-central nervous system interrelationships. In P. Black (Ed.), Physiological correlations of emotion (pp. 205–227). New York, NY: Academic Press.