Chapters 6- Cognition 06. The limbic system

06. The limbic system

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"The emotion, it is a magical product or is it a physiological process that depends on an anatomical mechanism?" James Papez.

1. History.

The term limbic (Limbus board which means in Latin [ 39 ]) was first introduced by the physician and anatomist Paul Pierre Broca French in 1878 [ 74 ]. The latter designated by the great limbic lobe extra lobe involved in emotion and particularly consisting bulb and olfactory tract, hippocampus and cingulate gyrus (cingulate is a belt in Latin) [ 75 ]. Of course, it is not currently recognizes the limbic system [ 32 , 41 ] as a true lobe [ 38 ].

In 1937, the American neuroanatomist James Papez published research [ 80 ] on a circuit emotions now called the Papez circuit [ 38 , 50 ]. This circuit includes the hippocampus, cingulate gyrus [ 41 ], thalamus, hypothalamus and some of their interconnections.

A few years later, in 1949, Paul MacLean [ 39 ] Papez resume ideas and integrate them with the concept of the great limbic lobe proposed by Paul Broca, leading to the notion of a limbic system [ 80 ].

Since then, other anatomical structures are gradually added to this notion as the prefrontal cortex and the orbitofrontal region [ 71 ].

2. Functions of the limbic system:

The limbic system is a group of brain structures that play a very important role [ 39 ] in behavior, especially in emotions, memory, learning and executive functions [ 161 , 162 ].

The emotion in the field of neurophysiology does not mean feeling, which is purely internal and subjective experience that a person feels about a particular situation. Emotions are rather physiological responses that accompany these feelings, changes in behavior or organ function [ 176 ].

The limbic system is often called (visceral brain or emotional brain [ 119 ]) because it plays an important role in a wide range of emotions including pain, pleasure, docility, affection, anger, aggression, fear, pleasure ...

Executive functions include skills related to planning, working memory, anticipation, initiative, organization, problem solving, logical reasoning, cognitive control, abstract thinking, learning rules, selective attention, the selection of motor responses, motivation ...

Executive functions are mainly related to the functioning of the prefrontal cortex and the orbitofrontal region [ 177 ].

The limbic system also affects the endocrine system and the autonomic nervous system [ 166 ].

3. Anatomy of the limbic system:

The limbic system comprises several cortical and subcortical structures located around the thalamus [ 80 ]. All these structures would form an integrated system which ensures the survival of the individual implementation of visceral responses and appropriate behavior.

Since the 50s, the list of brain structures related to the limbic system continues to grow among these key structures are: the cingulate gyrus [ 32 ] or the cingulate gyrus, the hypothalamus, the anterior thalamic nuclei, the olfactory system, the hippocampus, the amygdala ...

At the heart of this system is the Papez circuit which is very important for memory. In this circuit, information flows in a loop from the hippocampus to the mammillary bodies of the hypothalamus (via the fornix) and password to the previous thalamus nuclei then the anterior cingulate cortex to return to the hippocampus.

The amygdala [ 38 ] plays many roles, he is involved in olfaction, the emotions and especially in developing appropriate responses to the dangers [ 96 ]. The classic experiment of mice that had destroyed two tonsils shows that it does not tend to flee a potential predator.


Chapters 6- Cognition 06. The limbic system