What Happens to Your Brain When You Get a Concussion: a Deeper Dive

Foundational ideas and pictures explaining what happens to your brain when you get a concussion

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For more details, read on below!

So you want to know as much as you can about what happens to your brain when you get a concussion? We’ll do our best here to help you in your search for understanding.

To understand what happens to your brain when you get a concussion (also known as an mTBI), it is helpful first to understand how the brain works.

The brain is made up of cells called neurons, which together form web-like networks of connections. An axon is a part of a neuron that helps one neuron communicate with another.

A more in depth explanation about what happens to a concussed brain. This expands on ideas introduced on our simpler page.

This network of communication allows you to make sense of the world around you, learn new things, feel emotions, and function in your daily life. These connections in your brain are responsible for directing all of your thoughts and actions.

Here’s a video that can help you learn more about neurons and how the nervous system works.

Neurons communicate with one another by processing information in their cell bodies and then sending an electric signal down their axon. If the axon is a highway for signals, the neuron cell body is a toll-booth-like checkpoint which lets a signal continue only if it is big enough. Once the electric signal has reached the end of the axon, chemicals flow out of this cell and nudge a neighboring neuron to repeat the process.

This downstream communication between neurons is like if you tap a friend’s shoulder and ask them to “pass it on” by tapping another friend’s shoulder, continuing down a line.

You might be asking yourself, how does the electric signal flow down the axon? The answer lies in the exchange of chemicals flowing in and out of the axon. These chemicals are called ions. When at rest, axons have some ions inside the cell and some on the outside.

Once the cell body has “told” the axon to send a signal, ions from inside the axon flow out, and ions on the outside flow in. This flow of ions continues down the axon in a controlled way. This ion movement traveling down the axon is called an action potential.

The goal of an action potential is to pass a message along to another neuron. This messaging from one neuron to others can travel both into and out of your brain. Your neuronal networks connect every part of your body and certain ones are responsible for your senses and muscle movements.

This video can help you learn more about how an action potential works.

In order for a neuron to send a new signal, it needs to “reset” by returning it’s starting chemical balance. This balance is achieved when the right types and amounts of ions are inside and outside of the cell. Energy is required to restore this balance.

Now that you have a better understanding of how the neurons in your brain communicate, by forming vast networks that allow us to do almost everything, let’s focus on concussions.

When you get a blow or jolt to the head, the brain gets jostled and moves like jello in the skull.

Neuron cell bodies and axons are made of different materials and they have different densities. The difference in density means that cell bodies and axons move at different rates, so when a brain moves suddenly, a cell’s axon can move faster than its cell body and the cell can get hurt. The sudden brain movement from a concussion leads neurons to stretch and sometimes break.

The stretching and breaking disrupts communication between neurons in the brain. The unique disruptions involved in each brain injury are part of the reason why concussion symptoms vary so much. Depending on where the damage is in your brain, you may have different symptoms. For example, because two thirds of your brain connections are involved in your visual system, many people recovering from a concussion have difficulty with visual processing. Learn more about treatment for visual problems after a concussion for those with persistent symptoms.

If you may have recently gotten a concussion, here’s a good place for you to find information on navigating recovery.

Guidelines for Recovery

Start here

Difficulty with headaches, balance, spatial awareness, dizziness, memory, learning, and emotional management are all very common in the aftermath of a concussion. The brain controls everything that we do, so damage to the neuronal connections in our brains that allow for everyday tasks helps explain why concussions can be so frustrating.

Research shows that neurons deep within the brain are most affected by this movement. A part of your brain deep in the center of it, called the corpus callosum, connects the two hemispheres of your brain. This fragile connection has been found to get injured in many concussions.

In this video, David Camarillo, PhD, talks about some of his recent research and understanding of concussions. Between 2:27-4:30 and 7:38-10:10, Dr. Camarillo talks about what happens inside the brain.

Along with the stretching and shearing of neurons, the supportive layer of insulating cells around the axons (myelin sheath cells) can sometimes be torn. These myelin sheath cells function to support the neurons and speed up their communications. They help the streamline the action potential down the axon so that the signal can reach another neuron. The breaking of axons and injury to myelin sheath cells may help explain decreased reaction time during recovery from a concussion.

This disruption of neurons leads chemicals, called ions, to flow in and out of the cell.

This leaking can cause action potentials. A concussion disrupts a ton of your cells and causes a ton of leaking all in a short time frame right after the impact. This means that when you get a concussion, your neurons fire rapidly, disrupting regular communications inside the brain.

After a concussion-causing brain movement and some stretching and breaking of neurons, a chemical called calcium enters the neurons and may spread to surrounding cells. Calcium is not good for cells. In excess, this chemical can hurt your cells in more than one way. High amounts of calcium can damage cells, so neurons may need to remove the calcium. More energy is needed to remove this extra calcium from cells.

To summarize, after a concussion, your neurons may be in chemical imbalance, and lots of energy is required to bring them back to a state where they can function correctly.

One important form of energy that cells use is a chemical called ATP. After a concussion, so many neurons need ATP all at the same time that this demand overwhelms the system and depletes ATP energy supply. Very shortly after a concussion, a huge energy deficit develops. This energy deficit persists until your body is able to restore a high enough energy production to meet your body’s energy demands, and this metabolic recovery takes time.

Unfortunately, as we will explain next, not only does a concussion lead you to need more energy: it also makes it harder for your brain to get energy in the first place. Consequently, it takes a long time for your body to generate enough ATP for return to normalcy of your internal functioning.

To understand how a concussion can make it harder for your brain to get energy, it is helpful first to learn how the brain normally gets its energy.

As we explained above, ATP is an important energy source of cells. Your body makes ATP from glucose (sugar), which comes from the food you eat. Glucose is transported throughout the body through the bloodstream. Once glucose reaches the brain through the blood, it enters neurons. Once in the neuron, the mitochondria (the powerhouse of the cell) transforms that glucose into ATP.

Unfortunately, when you get a concussion, this mechanism is disrupted in multiple places.

First of all, concussions lead to decrease in blood flow to the brain. This means that less glucose is traveling to the brain, and, therefore less ATP can be made.

The stretching and shearing of neurons after a concussion also leads calcium ions to enter the neuron and then the mitochondria. When calcium enters the mitochondria, this causes an ion imbalance that disrupts its mechanisms. This incapacitates the mitochondria and decreases the amount of ATP they can produce.

In this period of decreased ATP levels, your body directs a maximum of energy to restoring the balance, particularly in your neurons. As most of your energy is funneled towards your recovery, less is available for your daily functioning. You may feel very fatigued as a result. This is normal.

Over time, your body reroutes mechanisms to find the path of least resistance. However, some abnormal shortcuts may replace expected pathways. Rehabilitation focuses on rebuilding neuronal pathways and forming new ones. Patterns are relearned. Systematic functions and processes that once worked for you may not work the same way as they did before. Intentional practice can help reroute and strengthen neuron connections and your brain’s internal communications.

Through rebuilding pathways, it’s possible to lean on your strongest established pathways to compensate for weaknesses and help you function. Your neuronal networks are strengthened through repetition and use, demonstrating why rehabilitation exercises make a difference. Taking your rehabilitation seriously is one of the most important actions within your control to improve your functioning after a concussion.

When your brain’s ATP supply is still below what’s needed to function, an additional traumatic insult triggers an even more dangerous metabolic cascade. In the event of a secondary insult, your ATP levels dip further than before. ATP declines compound on one another, meaning that your body will have an extremely amplified endeavor to bring up your deficient ATP levels. Recovery for secondary insult patients has been observed in a small sample of unfortunate patients to be increased more than two-fold in length and with a significant increase in reported symptoms and symptom severity. Second impact syndrome makes a serious injury become severe and potentially fatal.

This process of events that happens in your brain after receiving a concussion has been labeled as a “neurometabolic cascade,” by Dr. Giza. Dr. Giza is one of the leading researchers on what happens to a concussed brain. To learn more about the neurometabolic cascade from him, check out his explanation in the video below, starting at 0:37.

During this period, before your ATP levels rise back to normal, you and your brain are more vulnerable. You may reach ATP level normalization at earliest between 22-30 days after sustaining a concussion. Your symptoms may seem to disappear as early as 7-10 days after. The symptomatic and functional recovery timelines are not the same. You need to be especially careful during this period when you may believe that you are in the clear from your injury because you and your brain are still at increased fragility whether or not you realize it.

We hope our above explanations may help you better understand what happens to your brain when you get a concussion and provide you with a foundation for you to seek and uncover more information as you wish. Research is ongoing, and there are many gaps in knowledge on concussions and concussion care. Fortunately, numerous people do care and are striving to fill in these gaps. Around the world, concussion advocates are promoting education and support for individuals affected by brain injury.