Lenticular nucleus: parts, functions and associated disorders.

Thanks to this component of the basal ganglia we are able to learn and create concepts.

The basal ganglia are a series of parts of the brain located deep in the cerebrum that are of great importance for the performance of various functions. They are a set of various structures and substructures, which can be grouped according to their connections with each other.

One of these structures, or rather, a group of them is the so-called lenticular nucleuswhich is especially relevant in the management of motor skills, as well as in learning and motivation.

The lenticular nucleus: parts and characteristics

The lenticular nucleus is a subcortical structure of the brain, located in the inner part of the brain. This nucleus is part of the basal ganglia, a set of structures made up of gray matter (i.e., it consists mainly of neuronal somas and dendrites).

Also called extraventricular nucleus of the corpus striatumThe lenticular nucleus is made up of three segments, although these three segments can be divided mainly into two structures; putamen (which would be the outermost segment) and globus pallidus (which would include the middle and inner segments).

Thus, it can be considered that the lenticular nucleus is the union of two other structures of the basal ganglia, putamen and globus pallidus.

This cuneiform structure is in contact with the internal capsule, which separates it from the thalamus and caudate, and with the external capsule which separates it from the claustrum and insula. It connects with the aforementioned thalamus, the cerebral cortex and the set of structures that make up the brainstem.

Functions associated with this subcortical structure

The lenticular nucleus, as well as the set of structures that make up the basal ganglia, is a structure or set of structures of great importance for the correct vital functioning of the human being. Specifically, it has been observed that it has great importance in the following areas.

1. Motor skills

One of the aspects in which most research has been done and which has been known for the longest time is the great importance of the lenticular nucleus in motor skills and the management and coordination of movement.. Its main task in this sense is the adaptation of the movement to the situations that are being experienced and the adjustment to situational demands.

2. Posture maintenance

The lenticular nucleus is involved not only in the realization of specific movements, but also in the maintenance of posture. Damage to the lenticular nucleus may cause gait difficulties, incoordination or uncontrollable tremors.incoordination or uncontrollable tremors.

3. Automation of movements

The automation of movements is also affected by the lenticular nucleus, as it allows habituation to be acquired.

4. Learning

The lenticular nucleus influences learning processes. Specifically, it helps to generate procedural learning. In addition, through its various connections, the lenticular nucleus contributes to the creation of categories when organizing and structuring the world.

5. Motivation

Like other areas such as the caudate nucleus, the lenticular nucleus also contributes greatly in linking the rational with the emotionalallowing both types of information to be integrated. This means that thanks to their connections we can link a knowledge or stimulus to an emotion, which can motivate or demotivate us.

Disorders linked to the lenticular nucleus

The presence of alterations and lesions in the basal ganglia can have devastating repercussions on the health of the organism, as well as diminish its most basic capacities. Some of the alterations that are linked to damage in the lenticular nucleus are the following.

1. Subcortical dementias

The progressive degeneration caused by this type of dementia tends to start in different subcortical structures, one of the most frequent being the basal ganglia. Dementias caused by Parkinson's disease or Huntington's chorea are two of the best known, which present with gait incoordination, different spasmodic movements either at rest or during the performance of movements and a loss of memory and executive abilities.

2. Psychomotor disorders

Disorders such as tic disorders or Gilles de la Tourette, or Parkinson's disease itself, without necessarily causing dementia, are also influenced by the alteration of the basal ganglia.

3. Obsessive-Compulsive Disorder (OCD)

OCD has also been linked in part to hyperactivation of the basal ganglia, especially the caudate nucleus and putamen (the latter being part of the lenticular nucleus).

4. ADHD

ADHD is another disorder that is influenced by the presence of damage in the lenticular nucleus, making it difficult to maintain motivation and enhancing the appearance of tics and agitation.

Bibliographical references:

• Carlson, N.R. (2014). Behavioral Physiology (11th Edition). Madrid: Pearson Educación.

• Kandel, E.R.; Schwartz, J.H. & Jessell, T.M. (2001). Principles of neuroscience. Fourth edition. McGraw-Hill Interamericana. Madrid.