The Amygdala: Exploring The Function And Psychology Of Fight Or Flight

Medically reviewed by Julie Dodson, MA
Updated May 28, 2024by BetterHelp Editorial Team
Please be advised, the below article might mention trauma-related topics that include suicide, substance use, or abuse which could be triggering to the reader.
Support is available 24/7. Please also see our Get Help Now page for more immediate resources.

Based on their understanding of brain function, clinicians have been able to develop therapeutic interventions to help clients cope more effectively with fear, stress and anxiety disorders in many different contexts. 

While many believe that we've learned much about the role of the amygdala and the fight or flight response, researchers generally acknowledge that the amygdala has other functions that we don't yet fully understand. However, the information that we do have available can provide insight into why we respond and behave in certain ways, and what we can do to make our responses healthier.

Experiencing constant fight or flight mode?

Amygdala function: Psychology of the brain

The amygdala is a small, almond-shaped structure that is part of the limbic system of the human brain. Consisting of two temporal lobe structures, the amygdala helps facilitate several important emotional, behavioral, and cognitive processes. 

In a general sense, the amygdala can play a strong role in why we display emotions. The amygdala can have several functions in a neurotypical brain, but it may be most known for its role in helping our bodies process fear by initiating a fight or flight response to dangerous or threatening situations or stimuli.

Scientists have recently learned that amygdala neurons can activate in response to positive stimuli, and can be associated with memories that have either a strong positive or negative component. Current studies are exploring how the amygdala might affect other realms, such as addiction and social interaction. For example, research suggests that abnormalities in the connection between the orbitofrontal cortex of the cerebral cortex and the amygdala are associated with social anxiety

Amygdala function: The psychology of fight or flight

To understand how the amygdala functions, you may consider how many people react when faced with a common fear: public speaking. At some point in our lives, nearly all of us might have been faced with the prospect of public speaking, or glossophobia. Estimates suggest that about 73% of people have some degree of glossophobia.

With this in mind, the fear of public speaking can create physiological symptoms such as an increased heart rate, increased respiration, butterflies in the stomach, and brain fog prior to a presentation due to the perception of stressful or “threatening” stimuli that can be associated with the action of public speaking.

When we feel threatened, the hypothalamus can trigger a fight-or-flight response. This can start by the thalamus sending a signal directly to the amygdala before it gets processed in the cortex—which is generally where higher-level thinking occurs in most. This is why we can experience a sense of fear before we even have time to think about it. 

As the time nears to begin speaking, the amygdala can tell the hypothalamus to signal the body to prepare an extra dose of energy to flee the perceived threat. The body's response to this might be to increase one’s heart rate and respiration rate, as well as activate the sweat glands for cooling and a fast getaway.

When we think about a potential threat, our body can respond by becoming nervous, even if the threat never materializes.

Studies have shown that the amygdala is overactive in people who live with severe anxiety. Researchers also hypothesize that other areas of the brain, such as the hippocampus and the prefrontal cortex, can also be a part of anxiety disorder-related processes. 

The amygdala plays a vital role in emotional responses

Heinrich Kluver and Paul Bucy conducted some of the first experiments involving the amygdala. For example: they removed the amygdala of rhesus monkeys and recorded drastic changes in their behavior. 

The monkeys in this experiment generally became docile and seemed to display little to no fear. This phenomenon can be defined as Kluver-Bucy Syndrome, and it has led to similar studies that explored the role of the amygdala in fear and anxiety disorder formation.

In other studies, researchers used mice to study the role of the amygdala in fear. According to related research documentation, they worked with mice that had intact amygdalae. The experiment generally consisted of a researcher playing a tone and then giving the mouse an uncomfortable shock on their feet. Thus, they conditioned the mice 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 in this test group reportedly weren't able to remember that the tone came before the shock, and didn't display the same behavioral responses of fear at the sound of the tone.

In addition to helping facilitate the fear response, the amygdala plays an important role in positive emotions, such as happiness. Research shows that the right and left amygdala are activated during emotional responses. Amygdala activity has also been implicated in certain mental health disorders. For example, research shows that amygdala hyperactivity occurs during periods of emotional arousal in individuals with bipolar disorder. Abnormalities in the amygdala have also been connected to temporal lobe seizures. Amygdala enlargement is connected to a specific form of temporal lobe epilepsy

The basolateral amygdala and other nuclei

Located in the temporal lobes of the brain, the amygdala comprises several nuclei: the basolateral amygdala, central nucleus, cortical nucleus, medial nucleus, and intercalated cell clusters. These nuclei play important roles in processing sensory stimuli, fear conditioning, and other crucial functions. The basolateral nucleus of the amygdala is one of the most important groups of nuclei. It helps with emotional learning and the storage of emotional memories. The basolateral nucleus also helps facilitate the memory process in other brain regions, such as the entorhinal cortex. 

The nuclei of the amygdala receive inputs from, and send information to, several other regions of the brain. Amygdala connectivity from the prefrontal cortex to the central nucleus of the amygdala is thought to play a role in anxiety. The central amygdala assists the body in responding physiologically to stress. Excess neural pathways from the central amygdala are thought to cause an increased physiological stress response that can lead to anxiety. Additionally, the basolateral amygdala connects with the nucleus accumbens—the reward hub—to facilitate reward-seeking actions

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, trauma, and attachment-related areas of study. In an attempt to develop a simple model to explain the complex inner workings of the brain, Dr. Siegel developed a “hand model” that can demonstrate the functions of various parts of the human brain in connection with the fight or flight response.

The hand model can be shown as follows: 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 for this experiment, be facing forward. Your palm and fingers can represent your brain, and your wrist can represent your spinal cord.

Now, if you lift your fingers and raise your thumb, you can see the “inner brainstem” that can be represented by the palm of your hand. You can then put your thumb back down, and you can now see the approximate location of the limbic area of the brain. This is considered by many to be the area that can contain the amygdala, hippocampus, thalamus, hypothalamus, basal ganglia, and cingulate gyrus in a traditional anatomical form.

The brainstem, the limbic area, and the cortex can commonly be referred to as the "triune brain." We can consider this triune structure in the context of the brain’s two hemispheres, located on the left and right side of the structure. To have neural integration and functionality, the signals generally must be sent through both halves of the brain and link the functions in both hemispheres. 

Let's take a closer look at what this can look like by region.



The brainstem is thought to control the body's energy levels through heart rate and respiration. It also can control our states of arousal. The activity within the brainstem can shape the areas of the brain above it, which are the limbic and cortical regions. During times of danger, clusters of neurons in the brainstem can put us in survival mode as they move the body into a state of fight, flight or freeze.

Limbic area

The limbic area is hidden deeply in the brain. The limbic area is also thought to be a critical region that can aid us in forming bonds and developing relationships. The hypothalamus, located in this area, can be considered the master endocrine “control center.” It can deliver and retrieve hormones via the pituitary gland.

When we feel stress, this can start a chain reaction in which the pituitary gland might stimulate the adrenal glands. These can, in turn, release cortisol and mobilize our energy. The process might work well in the short term, but it can create problems when cortisol levels remain elevated for long periods.

Prefrontal cortex

The outer layer of the brain is known as the cortex. The prefrontal cortex lies just behind the forehead and is considered to be the spot that can connect the triune brain. The cortex is generally thought to control the subcortical, limbic, and brainstem areas, which can help us stay tuned in, connected, balanced and flexible. This control can be important because we can face many challenges on a daily basis that can require the triune brain to function well. When the limbic system becomes uncontrolled, we can lose our sense of connectedness and balance.

PTSD and fight or flight

Post-traumatic stress disorder (PTSD) is a mental health disorder that can occur after experiencing a deeply frightening, threatening event. Many experts believe that to recover from PTSD, we must risk exposing ourselves to feared memories, situations and places—in effect, retraining our brains at a structure level. 

Two types of therapy that can be effective for PTSD in most can include cognitive behavioral therapy and EMDR. Others may find relief through supportive strategies and lifestyle changes offered by a skilled in-person or online therapist. 

Other mental health disorders can develop because of issues with the limbic system or an overactive stress response. These can often be combatted and managed through professional intervention. 

Experiencing constant fight or flight mode?

How can online therapy help those “stuck” in fight-or-flight?

When you feel stuck in fight or flight mode, controlling the amygdala can help your body return to a normal state. If you need help learning how to do this, working with a therapist could be beneficial. However, when you’re experiencing PTSD, it may be difficult to attend in-person therapy. 

This is where online therapy can be helpful, as it can allow you to receive mental health care from your home. BetterHelp is an online counseling platform that can connect you with a therapist who has experience with stress and conditions like PTSD. You can talk with your BetterHelp therapist through phone calls, video chats or in-app messaging, according to your comfort level.

Online counseling can be an effective treatment for a variety of stress-related disorders, including PTSD. One study found details that suggest that an internet-based therapeutic intervention reduced PTSD severity as well as symptoms of co-morbid depression and anxiety disorder formation. Researchers also noted that “a positive and stable therapeutic relationship could be established online”.

Counselor reviews

“Veronica does a great job of listening and picking up exactly what I’m trying to explain even when discussing difficult subjects. She helps conversations flow in the direction that provides growth and healing from past trauma but also connects that with my current daily life.”

“Samantha is the best! I've had other therapists in the past but haven't been able to connect in the same way. I appreciate she will give me tasks to think about between sessions or things to actively work on that aren't a far reached and really help me rethink situations and how I deal with things. She's helped me through a traumatic year and I don't know what I would do without her!”


If you feel that you are living in a constant state of fight-or-flight, it can be helpful to remember that it doesn’t have to be this way forever. Understanding how to control your amygdala-related responses can help you experience more stability amidst life’s stressors. 

Online therapy may provide you with the comfort you need to discuss what is causing you emotional distress. BetterHelp can connect you with an online therapist in your area of need.

Explore mental health options online
The information on this page is not intended to be a substitution for diagnosis, treatment, or informed professional advice. You should not take any action or avoid taking any action without consulting with a qualified mental health professional. For more information, please read our terms of use.
Get the support you need from one of our therapistsGet started