LIMBIC SYSTEM
History
Paul Broca (1824-1880):
1878: “le grand lobe limbique”
Refers to a ring of gray matter on
the medial aspect of the cerebral
hemispheres.
 James Papez (1883-1958):
1930’s: defined a limbic system that might
underlie the relationship between emotion
and memory (Papez’ circuit).

Components
Amygdaloid body
 Hippocampus (“seahorse”)
 Cingulate gyus
 Parahippocampal gyrus
 Hypothalamus
 Mamillary bodies
 Anterior nucleus of thalamus

Functions

“Emotional brain
Emotional and motivational aspects of
behavior.
Provides emotional component to learning
process:
Especially the amygdala.

Associated with memory
Especially the hippocampus.

Associated with pain/pleasure, rage
Amygdala
Large nuclear group in temporal lobe.
 Afferents:

Olfactory tract
Solitary nucleus
Parabrachial nucleus
Limbic neocortex:
Cingulate gyrus
Parahippocampal gyrus
Amygdala Connections
Cerebral cortex
Olfactory system
Thalamus
Brainstem reticular formation
Stria
terminalis
Hypothalamus
AMYGDALA
Ventral Amygdalofugal
fibers
Regions of the Amygdala

Large basolateral region:
Provides direct input to basal ganglia and
motor system.

Small corticomedial group of nuclei:
Related to olfactory cortex.

Medial and central nuclei:
Connected to hypothalamus.
Amygdala Inputs
Olfactory
System
Temporal Lobe
(associated with visual,
auditory, tactile senses)
AMYGDALA
Corticomedial Nuclear
Group
Basolateral Nuclear
Group
Central Nucleus
Brainstem (viscerosensory relay
Nuclei: solitary nucleus
and parbrachial nucleus)
Ventral
Amygdalofugal
Fibers
Amygdala Outputs
Stria Terminalis
Septal Nuclei
Hypothalamus
AMYGDALA
Corticomedial Nuclear
Group
Dorsal Medial Thalamic Nucleus
Nucleus Accumbens
Hypothalamus
Basolateral Nuclear
Group
Central Nucleus
Nuclei of
ANS
Ventral
Amygdalofugal
Fibers
Ventral
Amygdalofugal
Fibers
Functions of the Amygdala
Relate environmental stimuli to
coordinated behavioral autonomic and
endocrine responses seen in speciespreservation.
 Responses include:

Feeding and drinking
Agnostic (fighting) behavior
Mating and maternal care
Responses to physical or emotional stresses.
Limbic System and Basal Nuclei
Anterior Cingulate Gyrus
Orbitofrontal Areas (10, 11)
Medial and lateral temporal lobe
Hippocampus
Amygdala
Entorhinal cortex (24)
Ventral Pallidum
Medial Globus Pallidus
Pars Reticularis
(Substantia nigra)
Ventral Striatum
(nucleus accumbens)
Caudate Nucleus
(head)
Ventral Anterior Nucleus
Dorsomedial Nucleus
Papez Circuit (Emotions)
Fornix
Mammillary bodies
Other hypothalamic nuclei
Septal nuclei
Substantia innominata
(Basal nucleus of Meynert)
Hippocampal Formation
(hippocampus
and dentate gyrus)
Parahippocampal Gyrus
Neocortex
Mammillothalamic
tract
Anterior Thalamic
nuclear group
Cortex of Cingulate Gyrus
Pathologies (lesions)
Voracious appetite
 Increased (perverse) sexual activity
 Docility:

Loss of normal fear/anger response

Memory loss:
Damage to hippocampus portion:
Cells undergoing calcium-induced changes
associated with memory
Kluver-Bucy Syndrome:
Results from bilateral destruction of
amygdala.
 Characteristics:

Increase in sexual activity.
Compulsive tendency to place objects in mouth.
Decreased emotionality.
Changes in eating behavior.
Visual agnosia.