How many things do we do in a day? We walk, run, pick up something with our hands, pick up a cup, write, look around... We do all this without any difficulty, without even thinking. But have you ever thought about how delicately and precisely all these movements must be controlled? Behind all this is our brain. A very small, but very powerful part of the brain helps us make all these movements smoothly and clearly. Today we are going to talk about that little hero. That is the Substantia Nigra.
So what is actually happening with the Substantia Nigra?
Simply put, the Substantia Nigra (SN) is a key part of our brain that helps control our movements. It is part of a system called the ``basal ganglia'', which is made up of other parts of the brain. It is like an important department in a large company. This part is important because of its influence on our movements and its contribution to the chemical processes in the brain.
Imagine you are driving a car. You need to use the accelerator to increase speed, the brake to slow down or stop, and the steering wheel to turn. Only when all of these are coordinated can you control the car properly. Similarly, the brain also has a similar system to control the movements of our body. One of the main functions of the substantia nigra is to produce a chemical called dopamine . This dopamine is a very important messenger that controls our movements and muscle function.
There are two main parts within the substantia nigra. The functions of both are slightly different.
1. SN pars reticulata: This part is mainly involved in our eye movements, learning ability and thinking ability. The cells in this part contain a chemical called gamma-aminobutyric acid (GABA) . This chemical controls the activity of brain cells to some extent, like a brake . If the brain decides that a certain signal is not good to go to a muscle, this `GABA` can be used to stop that unwanted signal or redirect it. This is why our movements are smooth, without being unnecessary.
2. SN pars compacta: This part is very important. Because the nerve cells (neurons) here produce the chemical dopamine that we talked about earlier. Dopamine is not only related to movement, but also to many things like our emotions, learning ability, reward, risk-taking, and motivation. When we do something pleasurable, we feel good and want to do it again because of this dopamine.
You may have heard of Parkinson's disease. In that disease, the dopamine-producing cells in this part of the brain called the SN pars compacta are gradually destroyed. When dopamine is lost, movement becomes uncontrollable, which is why patients experience symptoms such as tremors and difficulty walking.
Where exactly is this in the brain?
The substantia nigra is located in the middle of our brain, the midbrain. As the name suggests, it is located in the middle of the brain. It is located slightly above the brainstem, where our spinal cord connects to the skull at the base of the neck.
Even though we talk about the "substantia nigra," there are actually two parts of our brain like this. One on the right side of the midline of the brain, and one on the left. Both of these work in the same way.
What is its appearance, color, and size?
The name actually comes from Latin. "Substantia nigra" means "black substance." That's because, while most parts of our brain are a light pink-gray color, this part appears as a darker, black band than the rest of the tissue.
The reason for this is that the nerve cells in this part contain a pigment called melanin . Melanin is a chemical that is also found in our skin cells. When we go out in the sun, our skin turns brown and tans because of this melanin. That same pigment is what gives this part of the brain its special black color.
In terms of size, this is a very small part. It is said that about 25 parts of this substantia nigra can be placed inside a regular golf ball. Now you can understand how big the work is, even though it is so small.
What is this small part made of?
Like other parts of the brain, the substantia nigra is made up of two main types of cells.
1. Nerve cells (Neurons):
These are the main players in our brain and nervous system. It's like the telephone wiring system that carries information back and forth in our country. These cells transmit information in the form of electrical and chemical signals. There are several main parts to a nerve cell:
- Cell body: This is the main part of the cell, like the control center.
- Axon: A long, arm-like part that extends out from the cell body. It's like a long wire. Signals are carried along this.
- Synapses: Finger-like structures at the end of an axon. This is where an electrical signal is converted into a chemical signal and passed on to the next neuron.
- Dendrites: Small, branch-like structures on the cell body that act like antennas to receive chemical signals from other nerve cells.
- Myelin:A protective sheath around many wires. This helps signals travel faster and without leakage.
2. Glial cells:
These are the supporting cells that help the nerve cells. It's like a supporting cast that sets the stage for the main actors and helps them. Although these cells don't transmit signals, they provide the nerve cells with the nutrients they need, protect them, help protect the nervous system from infections, and it's these glial cells that make the myelin sheath. There are about ten times more glial cells than nerve cells in our nervous system.
What conditions affect the Substantia Nigra?
If this small part is damaged or its function is impaired, serious problems can occur. Here are some of the main medical conditions that affect this:
- Parkinson's disease - This is the main and most well-known disease.
- Alzheimer's disease
- Brain tumors
- Head injuries, especially concussions and other serious traumatic brain injuries
- Toxic substances, for example chemicals like trichloroethylene (TCE).
- Infections (especially infections that affect the brain, such as encephalitis)
- Diseases caused by problems with the immune system, for example lupus
- Hereditary diseases, like Huntington's disease.
- Lewy body dementia
- Stroke
What are the common symptoms of this condition?
The symptoms of a disease affecting the substantia nigra can vary depending on the disease. However, the table below lists some common symptoms.
| Type of symptom | Commonly seen things |
|---|---|
| Problems with movements | Problems with balance and coordination of the body. Stumbling while walking. |
| Muscle-related problems | Muscle weakness, stiffness, and muscle spasms. |
| Tremor | Tremors of the hands, feet, or other parts of the body, especially when at rest. |
| Thinking ability | Difficulty concentrating, thinking, or solving problems. |
| Vision problems | Difficulty controlling eye movements, resulting in vision problems. |
What tests are done to detect such problems?
Your doctor will carefully examine your symptoms and, if necessary, may order various tests to check brain function.
- Blood tests: These can detect many things, such as immune system problems and toxins in the body (especially metals like copper and mercury).
- CT scan (Computerized tomography scan): Cross-sectional images of the brain can be taken to see if there is a problem.
- MRI scan (Magnetic resonance imaging): This can produce very clear, detailed images of brain tissue.
- PET scan (Positron emission tomography scan): This test helps to see how chemical activity in the brain occurs.
- Genetic testing: These tests can be done if there is any doubt that the disease is hereditary.
What are the treatments for these conditions?
Treatment options depend entirely on the condition you have. Some conditions can be controlled with medication. For example, in Parkinson's disease, drugs are given that increase dopamine levels. In other cases, surgery may be necessary.
While some diseases can be cured, most of these are chronic conditions. In those cases, the main goal of treatment is to control the symptoms and help the patient live as normal a life as possible. If you or someone you know is experiencing these symptoms, the best thing to do is to see a qualified doctor immediately for advice.
Things we can do to keep our brains healthy
We can't prevent some diseases, such as Parkinson's, which affect the substantia nigra. They can occur unexpectedly. However, there are many things we can do to reduce our risk of many diseases that affect the brain, especially things like stroke. These things are very important to protect the health of our brain.
- Eat a balanced diet: The food we eat directly affects our circulatory system and body weight. Both of these are very important for brain health.
- Be physically active: Exercising daily and maintaining a healthy weight for your body can go a long way in protecting your brain from conditions like high blood pressure and stroke.
- Wear safety gear: It is essential to wear safety gear like a helmet when working in areas where there are head injuries, especially when riding a bicycle or doing construction work. Head injuries can cause permanent brain damage.
- Manage your chronic conditions: If you have chronic conditions like diabetes, high blood pressure, or cholesterol, manage them as directed by your doctor. If these are not controlled, there is a greater chance of brain damage.
The substantia nigra is a very small part of our brain, but now you can understand how big a role it plays. This small part is essential for controlling our movements, vision, and emotions. With the advancement of medical science, we are learning a lot more about it. That knowledge will help us find better treatments for related diseases in the future.
Take-Home Message
- The Substantia Nigra is a very small but essential part of the brain that smoothly controls our movements.
- The chemical dopamine produced by this part is very important for movement, emotions, and motivation.
- Damage to this part can lead to serious conditions such as Parkinson's disease.
- A healthy lifestyle (balanced diet, exercise, and protection from accidents) can protect the overall health of your brain.
- If you have symptoms such as body tremors, difficulty with movement, or balance problems, see a doctor without delay.
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