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Nigrostriatal pathway of the brain: structures and functions

Nigrostriatal pathway of the brain: structures and functions

March 10, 2024

Dopamine is one of the main neurotransmitters of the brain, known above all for its involvement in the processes related to pleasure and reward systems. However, its role in motor control is fundamental, using the different dopaminergic pathways to travel through the brain.

One of these neural networks is the nigrostriatal pathway . Throughout this article we will talk about what structures make it up, as well as its role in brain functioning and the clinical implications that its deterioration entails.

  • Related article: "Parts of the human brain (and functions)"

What is the nigrostriatal pathway?

The nigrostriatal pathway is one of the four pathways that make up the dopaminergic system. Together with the mesolimbic pathway, the mesocortical pathway and the tuberoinfundibular pathway, it is responsible for transporting dopamine from one place to another in the brain.


To be more precise, the nigrostriatal pathway is one whose beams project from the substantia nigra to the striatum, specifically the caudate nucleus and the putamen. This way has a fundamental role in motor control , being the stimulation of the intentional movement the main function of this.

Injuries or alterations typical of disorders such as Parkinson's disease or chorea, affect the nigrostriatal path generating numerous symptoms. Likewise, D2 dopamine antagonists can induce extrapyramidal symptoms associated with pseudoparkinsonism.

Related structures

As mentioned above, the nigrostriatal pathway runs through the brain from the substantia nigra to the caudate nucleus and putamen, located in the striatum.


1. Black substance

The substantia nigra corresponds to a brain area located in the midbrain, which stores neurons that produce dopamine. It receives the name of black substance since its tone is darker than the rest of the surrounding areas, because the neuromelanin levels of this are the highest in the area .

The main function of the substantia nigra is related to eye movements, motor control, the search for reward, learning and addiction. However, most of them are also mediated by the striatum.

When this structure begins to disintegrate or starts a process of degeneration, there are conditions like Parkinson's disease , which leads to numerous motor and cognitive disorders.

2. Striated body

Also called striated nucleus, the striatum forms the subcortical part of the telencephalon. This structure is distinguished by being essential when transmitting information to the basal ganglia.


The set of structures that make up the striated body are the caudate nucleus, the putamen and the nucleus accumbens . However, in this article only the first will be described as an essential part of the functioning of the nigrostriatal pathway.

  • Related article: "Striated body: structure, functions and associated disorders"

3. Caudate nucleus

The structures known as caudate nuclei are located approximately in the center of the brain, very close to the thalamus . We speak of plural nuclei because there are two different nuclei in the interior of each hemisphere of the brain.

Traditionally, the basal ganglia have been associated with the control of higher-order motor skills. Within these functions, the caudate nucleus participates in the domain of voluntary control, as well as in learning processes and memory.

4. Putamen

The putamen is a system also located in the central area of ​​the brain, which represents an essential role in the control of movements, specifically in control and direction of fine voluntary movements.

In addition, the correct functioning of putamen exerts an important influence on operant conditioning and recent studies label it as the source of feelings of love and hate.

  • Related article: "Putamen: structure, functions and related disorders"

Role in brain functioning

As we have seen, the nigrostriatal pathway, and those structures that make it up, are responsible for govern and favor the control of voluntary movements .

In general, the control of movements is the result of the satisfactory combination of sensitive information and motor information coordinated by the central nervous system (CNS).

Within this motor control we find voluntary movements, involuntary movements and reflexes. However, in this case, voluntary movements are controlled by the nigrostriatal route.

Voluntary movements are carried out with the intention of achieving an objective, that is, they are proactive. Further, most of these movements can be learned and improved through practice

Clinical implications and associated disorders

Knowing the structures related to the mesocortical pathway and the functions it performs, it will be much easier to understand what effects or consequences the decrease in activity in these neural networks leads to.

This decrease in the level of activity can occur either by the administration of dopamine D2 antagonist drugs or by progressive degeneration of the pathway, which gives rise to diseases such as choreas or Parkinson's disease.

Antagonists D2

D2 antagonists are commonly used in the treatment of gastric problems such as nausea, vomiting or gastrointestinal problems. However, its action as a dopamine antagonist can cause unwanted extrapyramidal effects such as dystonias or pseudoparkinsonian movements.

Koreas

The choreas are a group of neurological conditions that are distinguished by causing a series of strange involuntary movements in the hands and feet in people. These impulses are caused by a series of intermittent and uneven muscle contractions , that is, they do not have a repetitive or rhythmic pattern, but rather seem to be transmitted from one muscle or another.

Within this group is the well-known Huntington's disease, benign family chorea or familial inverted choreoathetosis.

Parkinson's disease

Parkinson's disease is a motor disorder that is relatively common in people over 60 years of age. The origin of this disease is in a decrease in the production of dopamine, especially in the nigrostriatal route, which is no longer sufficient to supply the demands of the brain.

It is a disease that develops progressively, affecting first one side of the body to act later in the other. The main symptoms of this disease are:

  • Tremors in upper and lower extremities , hands, feet, jaw and face.
  • Hardening of the muscles of arms, legs and trunk.
  • Slowness of movement.
  • Alterations in balance and coordination.

2-Minute Neuroscience: Substantia Nigra (March 2024).


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