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What Happens To My Brain When I’m Anxious?

Ariannah Hood, LMSW

Everyone deals with anxiety to varying degrees and if you find yourself dealing with intense and consistent anxiety it can be helpful to know what is going on inside your brain and what you can do to counter it. 

Anxiety is a response to perceived danger and stressful events. We can actually credit stress and anxiety for helping our primitive ancestors survive by staying vigilant and responding appropriately to dangerous situations. However, today we face less life-threatening situations than our ancestors, yet our brain’s response to stress hasn’t developed quite as quickly as society has.

In modern times threats to our emotional wellbeing are enough to trigger debilitating anxiety. Some examples are anticipating a stressful workday, being in financial straits, forgetting to complete an important task, or being in an uncomfortable social situation. Usually, before or during these situations your brain triggers a fight-or-flight response. The fight-or-flight response is something we have in common with all living creatures. It’s a tool our brain uses to protect us from perceived danger and prepares us to either confront or flee the stressor. This results in physiological symptoms such as racing thoughts, increased heart rate, sweating, butterflies in the stomach or nausea, muscle tension, or an inability to concentrate. 

I will be using physician and neuroscientist Dr. Paul D. MacLean’s triune brain theory to explain more about the brain and how it responds to stress. The triune brain model states that every human’s brain can be divided into three distinct regions. 

The first region is the reptilian brain which houses the amygdala. The reptilian brain is the most primitive part of the human brain structure responsible for instinct and survival. When the amygdala feels threatened, it sends stress signals to the other regions of the brain. It’s important to note that this part of the brain functions off of instinct and not reason.

The second region is the mammalian brain which houses the limbic system. The mammalian brain is responsible for emotions, memory, audio communication, and social connection among other things. The limbic system also houses the sympathetic nervous system which is responsible for turning the fight-or-flight response on and off. 

The final region of the brain is the human brain which houses the neocortex. The neocortex is what differs humans from other animals. This part of the brain is responsible for higher executive functioning such as reasoning, decision making, logic, and abstract thinking among other important functions. The neocortex gives humans slight control over the other two brain structures, by allowing humans to rationalize and be conscious of their thoughts and feelings before reacting. 

Let’s use the example of public speaking as a perceived threat. Before the public speaking event, the reptilian brain tells the mammalian brain that it does not feel safe. This causes the mammalian brain to trigger the fight-or-flight response. This may cause symptoms like racing thoughts and an increased heart rate. While these symptoms can help you survive a life-threatening event, it won’t help at making you look collected and prepared to speak in front of the crowd. The neocortex starts to do what it does best, it thinks. And in a situation like this, it tends to focus on the negative and reminds you of all the possible ways you could fail and be judged during this public speaking event. This worsens the already activated fight-or-flight response and creates more anxiety.

The goal in stressful situations like this is to activate the brain’s relaxation system, also known as the parasympathetic nervous system. In order to counter the brain’s fight-or-flight response, you have to use a technique that slows your heart rate and sends a signal to your brain that you are safe and calm. You can engage your neocortex to counter the brain’s fight-or-flight by practicing mediation, doing a mindfulness exercise, or repeating a positive/encouraging mantra. You can engage your reptilian and mammalian brain directly by deep breathing for a few minutes, practicing progressive muscle relaxation, or using calming essential oils for aromatherapy. These relaxation techniques will calm your entire system and allow you to face the stressful situation aka the “perceived threat” with a more relaxed and less anxious brain. 

If you experience anxiety that is affecting your wellbeing and requires coping mechanisms, please reach out to the intake specialists at Symmetry Counseling and be connected with a counselor who can help.

Image from 


Harvard Mental Health Letter (2011). Understanding the stress response, 27(9), 4-5.

Holden, C. (1979). Paul MacLean and the triune brain. Science, 204(4397), 1066–1068. Retrieved from

Ploog, D. (2003). The place of the Triune Brain in psychiatry. Physiology & Behavior, 79(3), 487–493.

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