Amygdala Function: Psychology Behind Fight Or Flight

Based on their understanding of human 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 to feelings like fear and anxiety healthier.

Amygdala function: Psychology of the brain's temporal lobe and limbic system

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 processing sensory information in a manner that helps our bodies process fear and initiates a fight-or-flight nervous system response to dangerous or threatening situations or stimuli.

The limbic system within the temporal lobe

Scientists have recently learned that amygdala neurons can also activate in response to positive stimuli, and can be associated with memories that have either a strong positive or negative component, suggesting this almond-shaped organ and the overall limbic system’s function reach beyond fear conditioning. 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 emotional responses like 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 have been faced with the prospect of public speaking, or glossophobia. Estimates suggest that about 73% of people have some degree of glossophobia.

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 consider why.

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.

The amygdala plays a vital role in expressing emotions

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. 

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.

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 in each temporal lobe 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, and could in part contribute to bipolar disorder’s manic and depressive episodes. 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 disorders. 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 fight or flight response to fear

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.

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

Brainstem

Limbic area

Prefrontal cortex

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. 

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.