Articles

Papez's circuit, structure and function

Papez's circuit, structure and function

Papez's circuit is a brain circuit proposed by the American neurologist James Papez in 1937 and previously investigated by the German doctor Christfried Jakob. Papez, began to study this circuit that begins in the hippocampus, calling it at first: "the circuit of Fury" or as its first discoverer called it: "the visceral brain", thus proposing that this connection between various brain structures that form part of the limbic system was the basis of emotion control.

This, however, proved uncertain since it was later discovered that it is the amygdala, a key structure in the limbic system composed of a set of neuron nuclei, the main processor of emotional reactions, such as fear or aggressiveness.

Despite having been initially linked to emotional processing, Papez's circuit has a main function in memory and its processing, especially key in one of the main structures of the circuit: the hippocampus, a very important region for the memorial function.

Content

  • 1 From the circuit of Papez to the Limbic System
  • 2 Papez circuit structure
  • 3 Papez's circuit and its involvement with memory

From the circuit of Papez to the Limbic System

He was the American physicist and neuroscientist Paul Donald MacLean who later reconceptualized the discovery of the previous ones and proposed the Papez Circuit as limbic system, a concept that was later expanded with the adoption of other structures and functions. The form of limbo that the circuit possessed when observed thanks to neuroimaging was what caused MacLean to call it as such.

The limbic system, in which Papez's circuit is located, is the concept by which a set of structures located around the thalamus are known today, under the cerebral cortex, considered a very primitive and primordial system of the brain whose main role It is found in the formation of memory, learning, attention, emotions and behavior.

Papez circuit structure

Papez's circuit is a set of connected structures that begin and end in the hippocampus. The circuit would be connected as follows: The hippocampal formation would connect initially with the fornix, which in turn connects with the mammillary bodies, the mamilothalamic tract, the anterior nucleus of the thalamus, cingulate gyrus, the entorhinal cortex and finally, the hippocampus again, completing the circuit.

When the circuit was extended in its reconceptualization as limbic systemOther structures such as the hypothalamus or the amygdala, the main structure involved in emotion, were included.

The structures of the circuit of Papez initially looked like this:

  • Hippocampus: It is one of the main structures in the human brain and many animals, which has a fundamental implication in the consolidation of memory and learning.
  • Forix: It is a structure composed of white matter that originates in the hippocampus and connects different brain regions for its proper functioning. The fornix is ​​considered the connector of the structures of the circuit of Papez.
  • Mamillary Bodies: They are two structures that are at the base of the brain and send nerve impulses from the tonsil or hippocampus to structures such as the thalamus, thanks to the mamilothalamic tract
  • Mamilothalamic Tract: It is a nervous connection that connects the mammillary bodies with the anterior nucleus of the thalamus.
  • Anterior thalamus nucleus: They are an important set of nuclei located in the anterior area of ​​the thalamus, whose functions are associated with memory, learning and some behaviors with emotional implications such as sex.
  • Cingulate turn: It is a gyrus or "gyrus" found in the medial brain and connects structures such as the thalamus and the neocortex or the somatosensory areas of the cortex
  • Entorhinal cortex: It is a region located in the middle temporal lobe, which connects with structures such as the hippocampus or neocortex.

Papez's circuit and its involvement with memory

Many are the researchers who affirm that the structures that form Papez's circuit, beyond the hippocampus, have a strong connection with memory.

The Theta waves they are electromagnetic waves that are generated during the first phases of sleep and that appear after the interaction between the frontal and temporal lobes. These are usually used to measure the activity of the hippocampus and are related to activities such as learning and memory. Although the activity of theta waves was not synchronized between the hippocampus and other structures such as the thalamus, if this connection is found with some components of the circuit of Papez. In addition, damage to some structures such as the mamilotamic tract, as well as the anterior and lateral ventral nucleus, leads to a deterioration of language and memory. This also happens when there is a disconnection between the circuit of Papez and the mamillary bodies, just as damage to the fornix can cause amnesia.

Links of interest

Papez circuit. Dr Bruno Di Muzio. //radiopaedia.org/articles/papez-circuit-1

The historical origin of the circuit of Papez, "the visceral brain." Dr. Julio César Cortés. //saludiario.com/el-origen-historico-del-circuito-de-papez-el-cerebro-visceral/

Papez Circuit John Bigbee //link.springer.com/referenceworkentry/10.1007%2F978-0-387-79948-3_347