The brain is the most important organ in our body. This is made up of different parts, each of them with different functions. The substantia nigra is one of those parts and it contains neurons, the brain cells that transmit and conduct the neurotransmitter known as “dopamine.” This is responsible for functions related to reward, addiction and movement. Therefore, the substantia nigra is of utmost importance. In addition, it is part of what is known as the basal ganglia, although it is not exactly considered a basal nucleus) and is located in the center of the brain.
In this Psychology-Online article, we tell you What is the substantia nigra and what is its function?. Discover what it is like, the different functions it has and its relationship with dopamine and Parkinson’s.
What is the substantia nigra like?
What is the substantia nigra of the brain and what is its function? It is a group of neurons located in the part of the brain known as the midbrain and is part of the basal ganglia. If you are wondering what the substantia nigra is like, it is dark in color due to the high amounts of neuromelanin it contains. The substantia nigra of the brain is, in turn, divided into parts with different functions:
- compact part: serves as an input and to transmit signals to the rest of the basal ganglia. So through the compact part, dopamine can reach the striatum. Because this area has more neuromelanin, it is the darker of the two.
- reticulated part: this, on the contrary, is the output of the basal ganglia and from it the information is sent to other parts of the brain.
In this section we have seen where the substantia nigra is located and, next, we will see what the function of the substantia nigra in the brain is. Additionally, in the following articles, you will find information about and the .
What are the functions of the substantia nigra?
As we mentioned, the substantia nigra has two parts and each of them has different functions, most of them falling on the compact part. However, the reticular part is important for neuronal inhibition and eye movements. Next, we will see what the functions of the substantia nigra of the brain are:
- Reward: The substantia nigra, and specifically dopamine, is important for reward-related sensations. This means that, after performing a certain activity, we have pleasant sensations, that is, we feel rewarded. This will cause us to repeat said action in the future in order to obtain said reward. This would explain the functioning of motivation, sexual pleasure or addictions. It is, therefore, related to learning.
- Learning: Due to those reward mechanisms, we repeat the same action. Therefore, we learn to perform a certain behavior. For example, we learn to exercise daily because we release dopamine and feel better.
- Fine motor: A function of the substantia nigra of the brain is that it participates in the control and initiation of fine movements. Dopamine and its circulation pathways or dopaminergic pathways participate in this type of movements.
- Temporal perception: The substantia nigra also has a role in the perception of time, especially with regard to the time elapsed between two stimuli.
- eye movements: As we mentioned at the beginning, eye movements depend on the substantia nigra, specifically the reticular part. This is responsible for the correct execution of saccadic eye movements and the stabilization of the gaze at one point despite the movement of the head.
- Sleep regulation: The neurons that are responsible for transporting dopamine participate in the correct functioning of the REM phase of sleep.
Relationship between the substantia nigra, dopamine and Parkinson’s
As we have seen in a previous article, in the substantia nigra of the brain it is found and transports dopamine and this one has a important role in fine mobility. This refers to the small movements we make on a daily basis, such as picking up a spoon. This is why damage to the dopaminergic pathways causes one of the most characteristic symptoms of Parkinson’s: hand tremor.
Likewise, damage to the substantia nigra and, therefore, to the dopaminergic pathways, also influences other symptoms of Parkinson’s such as muscle stiffness or slowness in movement, sleep problems, low mood, since there is no feeling of reward. Still, Parkinson’s disease is precisely this: deficiency of dopamine secretion and the consequences that said deficit can cause.
To date, it is not known for sure what can cause this neuronal degeneration, which currently has no possibility of recovery, although the worsening has been slowed. Everything seems to indicate that the origin is a combination of biological and genetic factors. It is generally treated with drugs such as levodopa, which is the metabolic precursor of dopamine. That is, the treatment of the disease is based on increasing the amount of the substantia nigra of the brain.
This article is merely informative, at Psychology-Online we do not have the power to make a diagnosis or recommend a treatment. We invite you to go to a psychologist to treat your particular case.
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Bibliography
- Carpenter, M. B. (1994). Neuroanatomy. Basics. Buenos Aires: Editorial Panamericana.
- Lima, MMS, Andersen, ML, Reksidler, AB, Vital, MABF & Tufik, S. (2007). The role of the substantia nigra pars compacta in regulating sleep patterns in rats. Public Library of Science, 2(6), e513.
- Nolte, J. (1994) The human brain: introduction to functional anatomy. Madrid: Mosby-Doyma.