Anxiety’s Invasion in the Brain

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The Neuroscience Behind Anxiety

As an avid student who studied Neuroscience in college, I have always been interested in the “why” questions surrounding our behavior and feelings. I am also someone who suffers from anxiety and have wanted to know more regarding the questions: “why do I have anxiety?” and “how does anxiety invade the brain?”

Basic Anxiety Response:

1. We feel, we see, we sense something is going on in our environment. We encounter a stimulus that frightens us.
2. Our brain starts to process this in the emotional processing portion of our brain.
3. Adrenaline and the stress hormone, cortisol, are released from various glands
4. The amygdala starts processing all the information being gathered and sends signals to other areas of the brain to trigger our flight-or-fight response
5. Our anxiety invades our decision-making circuit in the pre-frontal cortex.
6. Our memories from the anxiety-triggering event are stored by the hippocampus. So, in more similar circumstances, we begin to feel anxious when presented with similar stimuli.

These basic 6 steps have a lot of different sub-steps associated with them, and this is what made studying and researching anxiety while obtaining my Bachelor’s degree in Neuroscience. I think these steps outline the anxiety response nicely for me so that I can grasp and understand the “how”.

Brain Regions:

Amygdala:

This is a brain structure in the limbic system that works with emotional processing. The amygdala combines our sensory signals and interprets them. This is what allows us to associate emotions with certain stimuli around us. For my memory’s sake, I refer to the amygdala as the Master Control Center for Emotions.

Hippocampus:

This structure is also in the limbic system, and the hippocampus is responsible for storing memories. We, as humans, mostly associate our fears and anxiety over memories from our experiences. It’s a prime example of our own natural conditional learning as we acquire fears and triggers for our anxiety.

Prefrontal Cortex:

This region of the brain takes the longest time to develop. This is the area of the brain that is responsible for helping us make decisions, focusing our attention, predicting the consequences of our actions (important in anxiety pathways), planning for the future and more.

Lobes:

Our occipital, temporal and parietal lobes contain structures and neural pathways where our sensory neural circuits send signals. Our occipital lobe collects information from the eyes, and the temporal from the ears. In the parietal lobe, there is the sensorimotor cortex where signals from the nerves can travel from a fingertip when you touch a surface, and the signal is transferred all the way to the region of the brain that is responsible for interpreting what was touched.

Brain Circuits

During my four-year journey through college, I spent plenty of hours spreading my brain thin on learning and studied all types of neural pathways of the brain. Learning more about the emotional processing systems in the brain was always significantly more interesting for me in my classes.

We have so many neurons throughout our whole body, and many of these nerves perform specific functions. Some allow us to sense things and send signals to the brain that allow us to interpret those. This is what helps us taste, smell, feel, hear and see. All of our senses are tied to a neural pathway.

Once this neural pathway makes its way into the brain, interesting things start to happen. All the individual parts and pieces of our brain perform a wide variety of functions. We are able to use emotional processing structures like those in the limbic system (the amygdala, hippocampus and more). This is where the interpretation of these signals occur.

Detailed Anxiety Response:

1. We sense something. This can be done by sight, sound, touch, taste or smell. Anxiety can be triggered by any of our five senses. The stimuli can trigger a response in either of the respective brain regions correlated to the triggering stimuli.
2. The signals are transferred to the thalamus after visual and auditory signals are sent to their respective lobes (occipital and temporal). The thalamus is a region of the brain that is central for the interpretation of visual cues and auditory cues.
3. Then, the cortex (surrounding outer region of the brain) helps us decide what we are seeing and/or hearing. The prefrontal cortex is particularly important (front of the head) in turning on/off the anxiety response when a triggering stimulus was or was not present.
4. Signals are sent to the amygdala, the regions of the brain that is primarily responsible for emotional processing. Its specific role in this particular pathway is “triggering the fear response”. Later on, the information that is passed on from the amygdala to other regions of the brain is emotionally significant.
5. Then, the bed nucleus of the stria nucleus (extended amygdala) “sets off an immediate burst of fear” and “perpetuates the fear response”. This is responsible for the longer-term fears and anxieties we have during our lifetimes.
6. Locus coeruleus receives signals from the amygdala and the bed nucleus of the stria nucleus and initiates many of the classic anxiety responses as this is responsible for producing and releasing norepinephrine within the brain. Norepinephrine and epinephrine are especially important in setting off the flight-or-flight response.

We store memories of our experiences throughout our lifetimes as well that are associated with our fears. This is what allows us to remember our anxiety triggers over our lifetimes. This structure that is most responsible for the storage of long-term memories is the hippocampus. All the emotional stimuli from the processing of visual or auditory stimuli and the release of norepinephrine from the locus coeruleus is stored in the hippocampus. We remember what we saw, how we felt and more.

Sources:

Anxiety and brain. Direct. (2017, January 20). https://directindia.org/resources/anxiety-and-the-brain/.

Holt, Daphne, J., et. al. (2008). Neuroanatomical Systems Relevant to Neuropsychiatric Disorders. Massachusetts General Hospital Comprehensive Clinical Psychiatry. https://www.sciencedirect.com/topics/medicine-and-dentistry/prefrontal-cortex

StoneRidge. (2021). How Does Anxiety Affect the Brain? https://pronghornpsych.com/how-does-anxiety-affect-the-brain/

Source Links:

Anxiety and Brain

How Does Anxiety Affect the Brain? 4 Major Effects of Anxiety

https://www.sciencedirect.com/topics/medicine-and-dentistry/prefrontal-cortex#:~:text=Cognitive%20Dysfunction,prospective%20memory%2C%20and%20cognitive%20flexibility.