Papez circuit: what it is, structure and functions

What is the Papez circuit?

The Papez circuitwas identified as an important part of the limbic system, which is a group of brain structures comprising a variety of functions including emotion, behavior, long-term memory and the olfactory system.

In the article aboutDr. Christofredo Jakob: History of the German-Argentine Neurological School,(1) they explain that the transcendence of the Papez circuit in cognitive pathological research is due to its ability to significantly influence memory, in addition to being the structure responsible for controllingemotions.

Structure of the Papez circuit

The Papez circuit has a complex structure, which is responsible for the fulfillment of all the functions it covers. They will be mentioned and described below for your understanding and understanding.

Hippocampus

The hippocampus can be recognized in general terms, as one of the main structures in the human and animal brain , which has as its main function the consolidation of memories and learning.

It is located inside the temporal lobe and is intrinsically and mainly associated with spatial and episodic memory.

Fornix

The fornix is the main constituent of the primary efferent system of the hippocampus, itis composed of white matter and connects different regions of the brain for their proper functioning.

In addition to the aforementioned, it is in charge of conducting information and signals from the hypothalamus to the hippocampus, even from one hemisphere to another. It is a small C-shaped structure and comprises the emotional part of the brain.

mammillary bodies

They are two gray spheroids, which are located at the base of the brain and are responsible for sending nerve impulses. They are related to memorial functions due to their main connections.

To highlight: In the research article on the Implication of the mammillary region in spatial learning , they explain that this region is critical for the execution of spatial learning tasks (2)

mammillothalamic tract

It is one of the nuclei of the thalamus and connects posteriorly with the mammillary body. It is responsible for transporting signals as support for spatial memory.

Anterior nucleus of the thalamus

They are, in fact, a group of nuclei that are located at the rostral end of the dorsal thalamus. They constitute anterior nuclei of the thalamus, whichperform a function of alertness and participate in the learning process.

cingulate gyrus

Also known as the cingulate gyrus, it is an area of the brain that is responsible for fulfilling functions that determine the activity of the entire limbic system.It is found in both cerebral hemispheres and is quite sensitive to pathologies.

entorhinal cortex

It is a region that connects through its structures with the hippocampus. It is located in the medial temporal lobe and its main functions areto function as a network for memory and orientation. It is recognized as an interface.

In addition to that, it is related to the sense of smell connecting with these pathways and with the visual ones.

Amygdala

The Brain’s Amygdala is the core of emotions, which also allows you to control your reactions based on fear and satisfying stimuli. It is located in the temporal lobes of the brain and is essential for the proper functioning of specific responses and processing of emotions.

It is small in size, although it seems to be linked to the individual’s ability to socialize. Among the main functions of this structure are

• Receiving information from the environment.
• Anticipation of emotional response.
• Development of social interaction capacity.
• Modulate episodic memory.
• Consolidate the storage of emotional information.

orbitofrontal cortex

It is in charge of regulating the social behavior of individuals, including the ability to make decisions and the inhibition of certain behaviors, when the situation warrants it, so we could also say that it is linked to criteria.

To highlight: There are studies at the Barcelona Clinic , where they explain that this brain structure makes it possible to predict decision-making even before the stimulus is produced (3)

Functions of the Papez circuit

The Papez circuit, as a structure made up of the different elements mentioned above, together perform essential functions for the proper functioning of our body. Some will be mentioned below.

Control emotional expressions

The participation of the mammillary bodies, the anterior nuclei of the thalamus and the circuits of the hippocampus are responsible for controlling emotional responses.

Note: These foundations were even raised in the years 1911 by Jakob, constituting through all the connections the understanding of the harmonious mechanism in charge of these functions.

Process Memory

Both the limbic system in general and the structure of the Papez circuit are the form of the capo complex in charge, above all, of long-term memory. In the same way, it intervenes in the production of the storage of memories and the processing of the information received.

In the work previously cited and titled Dr. Christofredo Jakob: History of the History of the German-Argentine Neurobiological School the interaction of the hippocampus, the amygdaloid nuclear complex, nuclei prior to the thalamus and the limbic cortex are discussed as responsible for the development of these processes. (4) .

Participates in the formation of learning

Learning, which is stipulated in the operation of the Papez circuit, is emotional and spatial.

They are closely linked to the development of long-term memory, especially for the consolidation of memories, since it is a slow process that involves an emotional reaction in order to be relevant and to be stored.

In an article in News Medical Life Sciences , they explain how the amygdala is the main structure involved in the process, although the hippocampus is also considered above all in the release of hormones that regulate consolidation (5)

Regulates attention

It influences the attention and perception of the information received. In the research work by JP Henry, entitled Neuroendocrine patterns of emotional response (6) for the year 1986, the particular patterns where perception is located and referred to were studied, especially in the development of control as a subject before certain stimuli.

Intervenes in certain emotional behaviors

As we have previously mentioned, responses to stimuli, especially emotional responses, are clearly linked to the Papez circuit, so the behavior and responses obtained are directed through this structure.

Papez Circuit Associated Disorders

Like all the various components of our body and especially at the level of The Central Nervous System, there are certain disorders that are involved or associated with them. Therefore, next, we will mention those that are associated with the Papez circuit.

Parkinson’s disease

It occurs due to the degeneration of the substantia nigra of the Midbrain , and the presence of damage to the Papez circuit is included. Thanks to this, a movement disorder then gradually develops, as a result of which uncontrollable movements and incomprehensible speech occur.

Nerve cells or neurons progressively break down and die, which prevents the transmission of some signals and brain activity becomes abnormal.

Alzheimer

• Hippocampus
• Medial temporal lobe .

Syndrome Korsakoff

This syndrome occurs under the consequences of chronic alcoholism and abnormalities occur in the circuit. When there is damage or loss of neurons, the Papez circuit is really affected and there is even an interruption in the connections of the system.

Amnesia

Transient global amnesia stands out mainly, which is a selective memory disorder based on episodic memory.

It produces loss even 48 hours of information. It is believed that there is a direct link with the memory functionality of the Papez circuit and the important role of existing connections for the preservation of thoughts and memories.

Key takeaways

• The Papez circuit was identified as an important part of the limbic system, which is a group of brain structures that comprise a variety of functions including emotion, behavior, long-term memory, and the olfactory system.
• This circuit is made up of a structure of brain elements that are responsible for fulfilling all the functions of said circuit, they are: The hippocampus, fornix, mammillary bodies, mamillothalamic tract, cerebral amygdala, entorhinal cortex, orbitofrontal cortex, cingulate gyrus and anterior nucleus of the thalamus.
• Among the functions of the Papez circuit are memory processing, especially long-term memory, the consolidation of memories; control emotional expressions, regulates attention, is involved in certain emotional behaviors, and is involved in the formation of learning.
• Disorders associated with the Papez circuit are those that affect the central nervous system such as Parkinson’s, Alzheimer’s, Amnesia and Korsakoff’s syndrome.