The human brain is configured by a large number of structures and substructures that account for the different body systems and the different cognitive and emotional abilities and capacities. All the information that we capture , for example, must be integrated in order to form a concrete representation of reality. It is also necessary to integrate different processes when responding to environmental stimulation.

There are different relay centres where such 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 Sub-Talamus?

The subthalamus is a complex structure linked to the management of body movement and which has a large number 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 globus pallidus.

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

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

Main divisions of the sub-talamus

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

1. Subthalamic core

One of the main structures of the subthalamus, the subthalamic nucleus, is an oval-shaped nucleus located in the central part of the uncertain zone (which we will discuss later). This brain region is of great importance due to the large amount of afferences 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 to the primary motor, prefrontal and premotor cortex, as well as to the thalamus and reticular formation.

2. Uncertain zone

Located between the lenticular and thalamic fascicle, the uncertain zone is one of the substructures of the sub-talamus. This lamella-shaped core is involved in the control of movement, forming part of the extrapyramidal pathway and in connection with the motor cortex . In its centre is the subthalamic nucleus

3. Forel Cores

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

Main functions

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

In addition to the motor control, it has also been observed that the subthalamus influences orientation and balance , and a greater risk of falling has been observed with the injury of the uncertain area.

Injuries to the subthalamus

The presence of subthalamic lesions often causes symptoms linked to the control of movement . In general, a lesion in this area tends to produce sudden and involuntary movements, such as spasms and choreic movements of the extremities.

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

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

Bibliographic references:

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