Subthalamus: Parts, Functions And Associated Disorders
The human brain is made up of a large number of structures and substructures that account for the different body systems and the different cognitive and emotional skills and abilities.
All the information we collect, for example, must be integrated in order to form a concrete representation of reality. Likewise, 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
The subthalamus is a complex structure linked to the management of body movement and that it has a large 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 globus 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 the following.
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 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 connection 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 motor, prefrontal and premotor cortex, as well as with the thalamus and reticular formation.
2. Uncertain zone
Located between the lenticular and thalamic fasciculus, the zona incerta 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 In its center 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 nervous 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 the management of movement. It is especially linked to involuntary aspects of movement and precise control of this 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 observing a greater risk of falls due to injury to the uncertain area due to their injury.
The presence of subthalamic lesions usually causes symptoms linked to movement control In general, an injury to 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 thing happens in the Sydenham chorea, of infectious origin. The degeneration of this structure causes the choreic movements typical of these diseases.
It is also observed that damage to the subthalamus in its connection with the globus pallidus can generate 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.
