The basal ganglia is a subcortical region that intervenes in various physical and cognitive functions, particularly in movement, both voluntary and automatic. The nuclei that make up this superstructure have been grouped in different ways, giving rise to overlapping names.

The putamen is one of the sections of the basal ganglia . In this article we will describe the structure, functions and disorders associated with lesions in the putamen, paying special attention to the relationship of this nucleus with the other regions of the basal ganglia.

What’s the contest?

The putamen is a brain structure that has a fundamental role in the preparation and execution of the movements of the extremities . It is part of the anatomical-functional region known as the “basal ganglia”, which regulates voluntary motor skills, automatic habits and procedural learning.

It consists of grey matter, i.e. bodies of neurons, amyelinic dendrites and glial cells. It is located below the cerebral hemispheres, at the base of the telencephalon and in the central part of the brain. It is approximately circular in shape.

The functions of the putamen depend on the neurotransmitters GABA and acetylcholine , as well as on encephalin, an opioid peptide involved in the perception of pain and its regulation. Gamma-aminobutyric acid or GABA is the main inhibitory neurotransmitter, while acetylcholine (ACh) activates muscle movement.

Structure and anatomy

The putamen, the striated body, the globus pallidus, the caudate nucleus, the nucleus accumbens, the subthalamic nucleus, the substantia nigra and the substantia nigra redus form the basal ganglia. The putamen is the outermost of these nuclei .

The word “ganglion” is normally used to designate groupings of neuronal somas that are located in the peripheral nervous system, so the nomenclature is paradoxical in this case, as the basal ganglia are located in the brain.

Morphologically and functionally the putamen is intimately related to the caudate nucleus, the globus pallidus and the nucleus accumbens ; as a whole, these three structures are known as the striated body. Likewise, we call “lenticular nucleus” the union between the putamen and the globus pallidus.

The putamen is connected to the substantia nigra and the globus pallidus by various nerve pathways. This allows the exchange of information between the basal ganglia and the cerebral cortex, with the thalamus performing its usual function as a relay nucleus.

Functions of the contest

The two main functions of the putamen are the regulation of movement and the facilitation of different types of learning . It is also involved in disgust and feelings of hate.

Let’s see what are the ways and mechanisms that allow the contest to fulfill these functions.

1. Regulation of movement

The putamen and the other structures that make up the striated body send afferences to the brain stem, to the regions of the thalamus involved in movement and to the motor cortex. These signals ensure that locomotion takes place properly.

Other motor activities related to the contest are the selection of movements, the regulation of motor learning and the planning of motor sequences. This structure is considered to be particularly important for the control of the arms and legs.

However, no specific motor function is attributed to the putamen, but this role is due to its connections with other structures, both cortical and subcortical.

2. Operating Conditioning

Operative or instrumental conditioning is a type of learning that is based on positive (reinforcement) or negative (punishment) consequences of the behavior. Dopaminergic and cholinergic neurons that are abundant in the basal ganglia play a key role in this respect.

3. Implicit learning

Implicit learning is that which takes place passively, through mere exposure to certain stimuli. Dopamine and acetylcholine are believed to explain this function of putamen, as is the case with operant conditioning.

4. Category learning

Scientific research suggests that putamen also influences category learning, that is, the broad psychological constructs that encompass other more specific ones. For example, the category “animal” encompasses the concepts “elephant”, “fish” and “fox”.

5. Disgust, contempt and hate

It has been theorized that putamen is involved in feelings of disgust and contempt because of its connections to the insula; this is known as the “circuit of hate” . Furthermore, it is believed that the putamen is also part of the motor system that acts as a consequence of these emotions.

Related disorders

Injuries in the putamen cause involuntary movements such as tremors, sudden spasms or chorus (rapid shaking of the feet and hands). These types of motor symptoms are very characteristic of damage to the basal ganglia, as well as the cerebellum, which is functionally related to these nuclei.

Various neurodegenerative diseases cause such motor symptoms because they destroy putamen tissue and other basal ganglia. In particular, Parkinson’s disease, Huntington’s disease and dementia with Lewy bodies stand out.

Other psychological and neurological disorders that are related to putamen are attention deficit hyperactivity disorder, Tourette syndrome, schizophrenia, obsessive-compulsive disorder and some types of depression.

Damage to this structure can also cause restless leg syndrome , a disorder characterized by a feeling of discomfort in the lower extremities. By moving them, the discomfort is reduced, so people with this disorder are forced to shake them. The symptoms appear in a state of rest, making it difficult to sleep.