It's All in Your Head: How Does PTSD Change Your Brain?
Photo by Timothy Dykes on Unsplash
In the previous Introduction to PTSD article, you learned that traumatization begins in the brain.
In this follow-up article, we’ll dive deeper into the brain’s role behind PTSD.
Read on for a detailed, easy-to-read overview on select brain structures, where you’ll learn about their functions and their role in the formation of PTSD.
What is the limbic system?
A healthy limbic system, as illustrated by a Spongebob meme. Note how everyone is working together.
Look at any popular travel blogger’s feed on Instagram. Colorful images of exotic landscapes, foods, and attractive human subjects will flood your screen. As you scroll, these images might evoke several responses. Your heart beats faster. Your pupils dilate. You feel inspired. You might even feel envious.
As these feelings swirl within you, something might compel you to keep scrolling.
What is that something and why does it make you feel the way you do?
That something is your limbic system.
Nestled in the center of the brain and the brain stem, the limbic system is one of the oldest parts of human neurology.
Nicknamed the “lizard brain”, the limbic system’s primary structures are your thalamus, prefrontal cortex, hypothalamus, hippocampus, and amygdala. It controls a gamut of responses, including your emotions, memories, sensory perception, bodily functions, and the feel-good chemicals that get released when we eat sweets or hug a friend.
Anatomy of the limbic system. Image source: https://courses.lumenlearning.com/boundless-psychology/chapter/structure-and-function-of-the-brain/
Instagram is practically engineered for your limbic system. Your thalamus processes the images you see. Your prefrontal cortex helps you decide who to follow or when to log off for the day. Your hippocampus stores the memory of how to use the app and how it makes you feel. And your amygdala is the structure to blame when you feel compelled to slide into someone’s DMs.
Meet the Limbic System
The hippocampus
Your hippocampus is like your brain’s librarian. Photo by Taylor Wright on Unsplash
The hippocampus is a seahorse-shaped structure located in each brain hemisphere.
It serves as a memory processing center; like a meticulous librarian, the hippocampus reviews every memory it receives, creates a folder for it, and stores it in a mental card catalog. If the hippocampus were human, it would be praised for being an agile worker, as it maintains short-term memories, long-term memories, creates associations between memories and various senses, and helps us navigate the world (spacial orientation).
For example, your hippocampus plays a huge role when you travel. It helps you navigate unfamiliar places, and it’s why you ditch your map after spending time in a new city.
The thalamus
Your thalamus is like your brain’s executive assistant. Photo by Christina @ wocintechchat.com on Unsplash
The thalamus is a smooth, oval-shaped structure located near the cerebellum. Like the hippocampus, the thalamus is split between brain hemispheres.
As a sensory processing organ, the thalamus is akin to a classy executive assistant. With the cerebral cortex serving as a CEO, the thalamus receives sensory information – touch, pain, temperature, taste, pleasure, sound – from the body’s sensory nerves, processes it, and passes it along to the cerebral cortex for interpretation.
The thalamus also contributes to sensory perception, where it decides which senses to register, which to ignore, and which senses require immediate attention.
For example, your thalamus is why you can’t feel your clothes after wearing them for a while.
The hypothalamus
Your brain’s IT department. Photo by Markus Spiske on Unsplash
The hypothalamus is located beneath the thalamus.
This little guy is like your brain’s IT department. It dutifully carries out its tasks, unseen and unheard as you move throughout the day – it regulates your hunger, thirst, pain and pleasure responses, your other kind of thirst, and aggression.
It also helps keep your body running by overseeing the autonomic nervous system – your pulse, blood pressure, breathing, hormones, and the physical aspects of emotional arousal.
The Prefrontal CORTEX
The prefrontal cortex is located at the front of your brain, directly behind your forehead.
As your brain’s emotional reasoning center, your prefrontal cortex is like a business consultant. Organized and logical, it’s responsible for a range of executive functions, including impulse control, emotional regulation, decision making, and the ability to consider the consequences of your actions (like sliding into someone’s DMs).
It also plays a large role in personality development, as it helps you make decisions according to your personal motivations, character, and goals.
The Amygdala
An activated amygdala is nothing to mess with. Photo by Nick Bolton on Unsplash
The amygdala is an almond-shaped mass located deep within the brain’s left and right temporal lobes. Don’t let its size fool you; the amygdala is an incredibly powerful emergency response and emotional processing organ.
It serves as a micro brain and is the source of your stress response. Activated by fear, anxiety, aggression, and rage, the amygdala has the power to hijack the rest of the limbic system. It has a hair trigger. It will cut you.
The Limbic System, Stress Response, and Memory
Our limbic system also has another purpose.
Survival.
When shit goes down, the limbic system flips its survival switch. Our thalamus receives sensory input, and if fear is generated by the input, our amygdala hijacks our prefrontal cortex.
Rational thought is thrown out the window as the amygdala activates your body’s stress response and floods you with adrenaline and cortisol. Adrenaline temporarily speeds up your metabolism; it raises your blood pressure and makes your heart beat faster. Cortisol temporarily makes us stronger and faster in preparation for fighting, freezing, or fleeing from the source of danger.
The stress response is immediate and unconcious. Once your amygdala takes the reins, it will make you do anything to survive.
Once removed from danger, your amygdala stops pumping your body with adrenaline and cortisol. As you come down from the stress response, your hippocampus preserves a mental snapshot of the event. Like how we only showcase our life’s highlights on Instagram, the hippocampus reduces the memory to its most important sensory components before storing it in our long-term memory.
Once returned to safety, the prefrontal cortex comes back online. It lets the amygdala know that the danger has passed. And with time, it uses higher emotional reasoning to process and integrate the traumatic memory.
The Limbic System and the Formation of PTSD
Too much traumatic stress throws the limbic system into disarray.
A traumatized limbic system, as illustrated by a Spongebob meme. Notice the implied miscommunication.
Once returned to safety, the prefrontal cortex can’t reach the amygdala. The overactive amygdala can’t pass on the traumatic memory to the hippocampus for storage. Unable to archive the memory, the hippocampus replays it over and over, as vivid as when you first experienced it. The thalamus replays the memory’s sensory components, and when fear is generated, the amygdala erroneously activates the stress response.
This feedback loop is the essence of PTSD, with PTSD being the result of miscommunication between structures of the limbic system. It’s the reason why traumatic memories follow a trauma survivor long after they’ve returned to safety. It’s the source of emotional disturbances and it occurs day and night within a trauma survivor.
The Limbic System and PTSD Recovery
Humans are resilient. The same can be said about the limbic system. Resetting the limbic system is the essence of PTSD recovery and is essential for managing one’s symptoms.
Just as there are many ways to be traumatized, there are many ways to reestablish communication within the limbic system. Details on the mechanics of resetting the limbic system and how to do so will be covered in a follow-up article.