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The Striated Core: structure and functions

The Striated Core: structure and functions

The striatum is a subcortical region that belongs to the anterior brain.

It is the main route of basal ganglia information and is directly connected to the cerebral cortex. In humans, this brain structure is divided by a section of white matter that is known as the internal capsule.

Content

  • 1 Structure and connections
  • 2 Shape and location of the striatum
  • 3 Striated core connections
  • 4 Functional aspects of striated nuclei
  • 5 Disorders of the striated nuclei

Structure and connections

The striated nucleus, or rather, the striated nuclei because there are more than one, are a region of gray matter that is found within the cerebral hemispheres. In this sense, they are subcortical structures that are located at the base of each hemisphere.

The two main nuclei that make up the striatum are the caudate nucleus and the lenticular nucleus. The latter, in turn, is formed by two structures known as putamen and pale balloons.

Shape and location of the striatum

The caudate is C-shaped (seen laterally), follows the course of the lateral ventricle, and has three parts: head, body and tail. Between the caudate and the putamen, there is a morphological continuity, since the anterior part of the caudate, the head, is attached to the putamen. The pale or pale balloon is located medially to the putamen and contains two parts: lateral segment and medial segment.

The caudate and the putamen share a common embryological origin, the histological aspect and similar connections, and they are called as a whole neostriate or simply striated, while the pale one is also called paleoestriate.

The putamen and the pale globe form the lentiform or lenticular nucleus (means 'lentil' in Latin).

The striated nuclei are part of a broader functional system called the basal ganglia system. This system is formed, apart from the striatum, the subthalamic nucleus and the black substance, and the injury of any of these structures can cause alterations in the control of movements (tremors, tics, etc.).

Striated Core Connections

The neoestriado (caudado-putamen)

The main references come from these points:

  • The cerebral cortex, mainly of the frontal and parietal part. They are the most abundant.
  • The black substance, which forms the black-striated pathway. It is an especially important dopaminergic affair because in Parkinson's disease there is an alteration in this pathway, and the neostriate is left without the entry of dopamine.
  • The intralaminar nuclei of the thalamus.

Eferences go mainly to the pale nucleus, although some of these fibers continue to the black substance.

Pale core

The references They come from the following elements:

  • The neostriate
  • The subthalamic core

From the pale come the main eferences of the striatum, is the exit path. The following places go:

  • The subthalamic core
  • The thalamus (lateral ventral, anterior ventral and centromedial nuclei). These thalamic nuclei project over the cortex.

Functional aspects of striated nuclei

The striatum has an important role in motor circuits. Specifically in the circuits called extrapyramidal, which are the ones that regulate non-voluntary movements.

As for the neostriate, it seems that the two nuclei that form it do not have the same functional implications. These implications are as follows:

Probably, the putamen has a central role in most motor functions of the striatum so that its connections are mainly with motor areas of the cortex.

For its part, the caudate seems to be involved in cognitive functions, since it receives projections of areas of association of the cortex and sends them to the prefrontal cortex.

Disorders of the striated nuclei

Many disorders of the striatum and basal ganglia in general produce motor alterations, such as involuntary movements and alterations in muscle tone.

We will treat two disorders of striated nuclei: Parkinson's disease and Huntington's disease.

Huntington's disease

The origin consists of a acetylcholine and GABA cell degeneration the striatum and cortex nuclei.

The cause of the disease is genetic.. Dominantly, a defective gene that is on chromosome 4 is inherited. The probability of affecting offspring, if a parent is affected by the gene, is 50%.

Typical symptoms appear between the ages of thirty and fifty and the main symptoms are involuntary, rapid and random movements of the trunk, extremities, face and tongue. They have difficulty speaking, swallowing, etc. They are increasingly pronounced and eventually accompanied by progressive dementia. There is currently no treatment, but in the future we could expect positive effects with gene therapies.

Parkinson's disease

The symptoms are of variable severity and are usually the following:

  • Tremor. It is usually resting, which mostly affects the hands; It decreases with voluntary movements and increases with emotional tension.
  • Muscular stiffness. It is due to hypertonia of all muscles, although the force is practically normal.
  • Difficulty and slowness to start and make movements. The blinking decreases, there is facial expression and the arms do not move accompanying the march.

In many cases, problems such as depression and dementia also appear.

The origin is in the degeneration of the black-striated dopaminergic pathway, since a neuronal death is observed in the black substance. The cause is not clear and many possibilities are pointed out: genes, toxins, etc.

You may be interested: Emma Watch, the clock that allows you to rewrite people with Parkinson's

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