Subtálamo: Parts, Functions And Associated Disorders

This brain region is part of the diencephalon and is essential in the control of movements.

The human brain is made up of a large number of structures and substructures that account for the different body systems and different cognitive and emotional abilities and capacities. All the information that we capture, for example, must be integrated by such to form a concrete representation of reality. In the same way that different processes must also be integrated when responding to environmental stimulation. 

There are different relay centers where these associations are made, such as the thalamus. But in addition to this there are different brain structures with similar functions, such as the subthalamus.

What is the subthalamus?

The subthalamus is a complex structure linked to the management of body movement and that has a great multitude of connections with different brain regions, such as the  substantia nigra and the red nuclei, although some of its most important connections are with the  globe pallidus..

This structure is part of the diencephalon and is located between the brain stem and the  cerebral hemispheres. Specifically, it can be found below the  thalamus, from which it is separated by the interthalamic limiting zone, and above the midbrain (specifically the tegmentum). It also connects with the  hypothalamus.

In addition to those already mentioned, other structures with which the subthalamus connects include the motor and  prefrontal cortex or the  basal ganglia.

Major divisions of the subthalamus

The subthalamus can be divided into the different structures that make it up. The main sections that can be considered within this brain region are as follows.

1. Subthalamic nucleus

One of the main structures of the subthalamus, the subthalamic nucleus, is an oval-shaped nucleus that can be found in the central part of the uncertain zone (which we will talk about later). This brain region is of great importance due to the large amount of  input it receives. The most relevant due to its link with movement management is the relationship it has with the basal ganglia, with which it interacts through the use of  glutamate.

It also has glutamatergic connections with the primary, prefrontal, and premotor motor cortex, as well as with the thalamus and the  reticular formation.

2. Uncertain area

Located between the lenticular and the thalamic fascicle, the uncertain zone is one of the substructures of the subthalamus. This sheet-shaped nucleus is involved in the control of movement, forming part of the extrapyramidal pathway and in connection with the motor cortex. At its center is the subthalamic nucleus

3. Forel cores

Nuclei of Forel areas are three small areas of white matter in the subthalamus, also called Forel fields, which act as nerve projections to different brain regions.

Principal functions

The subthalamus is a structure of great importance for the correct functioning of the human being, having a great role in the integration of motor information that allows movement management. It is especially linked to involuntary aspects of movement and its precise control, greatly affecting its connection and influence with the basal ganglia.

In addition to motor control, it has also been observed that the subthalamus influences orientation and balance, with a greater risk of falls being observed when  injured in the uncertain area.

Injuries to the subthalamus

The presence of subthalamic lesions usually cause symptoms related to movement control. In general, an injury in this area tends to produce sudden and involuntary movements, such as spasms and choreic movements of the extremities.

Regarding the latter, the lesion of the subthalamus is especially linked to  Huntington’s chorea, in which the subthalamic nucleus is especially affected. The same occurs in Sydenham’s chorea, which is infectious in origin. The degeneration of this structure causes the choreic movements typical of these diseases.

It is also observed that the lesion of the subthalamus in its connection with the globus pallidus can generate hyperkinesis or excessive uncontrolled movements. On the other hand, it has been proposed that stimulation of this region could be useful when it comes to alleviating the symptoms of Parkinson’s or other movement disorders, due to its effect on aspects such as locomotion and posture, through stimulation transcranial magnetic.

Bibliographic references:

  • Snell, RS (2006). Clinical Neuroanatomy. 6th edition. Editorial Médica Panamericana. Madrid.
  • López, L. (2003). Functional anatomy of the nervous system. Noriega Editores. Mexico.
  • Afifi, AK & Bergman, RA (2007). Functional neuroanatomy. 2nd edition. Mc Graw-Hill Interamericana. 

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