The Amygdala: Function & Psychology Of Fight Or Flight

By Toni Hoy

Updated March 09, 2020

Reviewer Dawn Brown

Researchers are working hard every day to try to understand the complex system of brain functioning. Studies and experiments have helped them learn much about the parts of the brain that control our emotional and behavioral responses. Brain research has helped researchers label various parts of the brain and understand how they function alone and in connection with each other. A notable psychiatrist developed a hand model that makes it easy to explain how the brain creates a fight or flight response when the body tells the brain that it's in danger.


By having a better understanding of brain function, clinicians have been able to develop therapeutic interventions to help us deal better with fear, stress, and anxiety. While we've learned much about the role of the amygdala and the fight or flight response, researchers acknowledge that the amygdala has other diverse functions, which we don't fully understand at this juncture.

Amygdala Function: Psychology Of The Brain

We know that the amygdala is part of the brain's limbic system. The word amygdala means almond and this part of the brain was aptly named for its almond shape. The amygdala is a collection of nuclei that are found in the temporal lobe. Two amygdalae reside in the brain-one in each hemisphere.

In a general sense, the amygdala plays a strong role in why we display emotions and why we behave the way that we do. The amygdala has several brain functions, but its best known for its role in helping our bodies process fear and threats by initiating a fight or flight response to dangerous or threatening situations.

Scientists have recently learned that the amygdala also activates in response to positive stimuli, as well as being associated with memories that have a strong positive or negative component. Some current studies are being explored as they relate to other realms, such as addiction and social interaction.

Amygdala Function: Psychology Of Fight Or Flight

At one point in our lives or another, nearly all of us have been faced with the frightening prospect of being asked to speak to an audience in public. The scientific name for fear of public speaking is glossophobia. Estimates suggest that about 75% of people have glossophobia to some extent.


The fear of speaking in public often creates physiological symptoms such as an increased heart rate, increased respiration, butterflies in the stomach, and trouble thinking well enough to get the words out. These reactions occur because our brain sends out a warning signal which warns other parts of the brain to respond to the body has a way of coping with present and immediate fear.

Whenever we're afraid or feel threatened, the hypothalamus triggers a fight or flight response. Without us being consciously aware of it, the thalamus sends a signal directly to the amygdala before it ever gets processed at the cortex. This action is what instantly creates a sense of fear before we even have a chance to think about it. While fear is an uncomfortable and frightening feeling, it serves an important purpose in protecting us because it allows us the chance to take action to eliminate the danger.

In the situation of having stage fright, our body's reactions tell us that we need to compensate for the fear. Some people try various methods of distracting themselves from the fear such as picturing audience members in their underwear or staring out into space rather than making eye contact with audience members.

As the time nears to begin speaking, the amygdala warns the hypothalamus to signal the body to prepare an extra dose of energy to deal with the fear. The body's response is to increase the heart rate and respiration and activate the sweat glands.

Since anxiety is a symptom of fear, it's easy to see the connection between the amygdala and anxiety. When we think about a potential threat, our body responds by becoming anxious, even if the threat never materializes. Studies have shown that the amygdala is overactive in people who live with severe anxiety. Researchers believe that other parts of the brain such as the hippocampus and the prefrontal cortex are also involved with anxiety symptoms.

What Has Research Shown Us About the Function Of The Amygdala?

Heinrich Kluver and Paul Bucy conducted some of the first experiments involving the amygdala. They removed the amygdala of rhesus monkeys and recorded drastic changes in their behavior. The monkeys became docile and seemed to display little or no fear. This phenomenon is called Kluver-Bucy syndrome, and it led to similar studies that explored the role of the amygdala in fear and anxiety.

In other studies, researchers used mice to study the role of the amygdala in fear. They worked with mice that had intact amygdalae. The experiment consisted of playing a tone and then giving the mouse an uncomfortable foot shock. Essentially, they conditioned the mouse to associate the tone with the shock. After repeated incidences of playing the tone and delivering the shock, the mice began to display fear as soon as the tone was played.

As a follow-up experiment, researchers used mice that had lesions on their amygdalae and repeated the steps of playing the tone and delivering the foot shock. The mice weren't able to remember that the tone came before the shock and didn't display fear at the sound of the tone.

A "Handy" Model Of The Brain That Demonstrates The Fight Or Flight Response

Dr. Daniel Siegel is a notable psychiatrist and clinical professor at UCLA who has done extensive work in neuropsychiatry and trauma and attachment.

On a quest to develop a simple model for how to explain the complex inner-workings of the brain, Dr. Siegel developed a simple hand model to demonstrate the functions of various parts of the brain in connection with the fight or flight response.

Place one of your hands up and put your thumb in the middle of your palm. Then, curl your fingers over the top of your thumb. Your knuckles should be facing forward. Your palm and fingers represent your brain, and your wrist represents your spinal cord.

Now, if you lift your fingers and raise your thumb, you can see the inner brainstem as represented by the palm of your hand. Put your thumb back down, and you now see the approximate location of the limbic area of the brain, which is the area that contains the amygdala, hippocampus, thalamus, hypothalamus, basal ganglia, and the cingulate gyrus.

Next, curl your fingers back over the top of your thumb, and your fingers represent the protective covering of the cortex.

These three regions of the brain-the brainstem, the limbic area, and the cortex are collectively referred to as the "triune brain." Integrating the brain encompasses a process that links these three regions together. As most people are aware, the brain also has two hemispheres-the left and right hemispheres. To have neural integration, the signals must be sent through both halves of the brain and link the functions in both hemispheres. Let's take a closer look at each region.



The brainstem controls the body's energy levels through heart rate and respiration. It also controls our states of arousal. The activity within the brainstem shapes the areas of the brain above it, which are the limbic and cortical regions.

During times of danger, clusters of neurons in the brainstem put us in survival mode as they put the body into a state of fight, flight, or freeze.

Limbic Area

The limbic area is hidden deeply in the brain. On your hand model, the limbic area is approximately where your thumb is. The parts of the limbic system work together to evaluate whether the situation is good or bad. If the situation is good, our emotions will kick into gear, and we'll move towards it. If it's bad, our emotions will tell us that too, and we'll move away from it.

The limbic area is a critical region that aids us in forming human bonds and attachment and developing relationships. The hypothalamus is the master endocrine control center. The hypothalamus delivers and retrieves hormones via the pituitary gland. When we feel stress, it starts a chain reaction where the pituitary gland stimulates the adrenal glands, which release cortisol and mobilize our energy. The process works well for the short-term, but it can create big problems when the cortisol level remains chronically elevated for long periods.


The outer layer of the brain is the cortex. The prefrontal cortex lies just behind your forehead.

The triune brain is connected. The cortex regulates the subcortical, limbic, and brainstem areas which helps us to stay tuned in, connected, balanced, and flexible. This regulation is very important because we face many trials and problems on a daily basis that challenge the triune brain to remain regulated. When the limbic system becomes dysregulated, we can lose our sense of connectedness and balance.

Using the hand model, dysregulation causes our fingers to flip up, exposing the limbic system which causes us to lose our flexibility and act in unreasonable ways and possibly even cause us to lose our moral reasoning ability. Essentially, by overloading the limbic system, we "flip our lids."

The good news is that we can take an emotional break and allow our fingers to recover the cortex, which allows us to re-regulate ourselves.

If you're someone who lives with post-traumatic stress disorder, severe anxiety or have weak attachments with people, you don't have to live in a constant state of fight or flight. The licensed counselors at BetterHelp can help you with coping strategies to prevent you from flipping your lid or return to a regulated state if you've already lost emotional control. The hand model serves as a reminder that the problem lies deep inside your brain and there are effective ways to keep your amygdala in healthy working order.

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