1. LIMBIC SYSTEM

2. 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 ( ):
1930’s: defined a limbic system that might underlie the relationship between emotion and memory (Papez’ circuit).

3. Components Amygdaloid body Hippocampus (“seahorse”) Cingulate gyus
Parahippocampal gyrus
Hypothalamus
Mamillary bodies
Anterior nucleus of thalamus

4. Functions Associated with memory Associated with pain/pleasure, rage
“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

5. Amygdala Large nuclear group in temporal lobe. Afferents:
Olfactory tract
Solitary nucleus
Parabrachial nucleus
Limbic neocortex:
Cingulate gyrus
Parahippocampal gyrus

6. Amygdala Connections AMYGDALA Cerebral cortex Olfactory system Stria
Thalamus
Brainstem reticular formation
Hypothalamus
Stria
terminalis
AMYGDALA
Ventral Amygdalofugal
fibers

7. 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.

8. Amygdala Inputs AMYGDALA Olfactory System Corticomedial Nuclear Group
Temporal Lobe
(associated with visual,
auditory, tactile senses)
Basolateral Nuclear
Group
Central Nucleus
Brainstem (viscerosensory relay
Nuclei: solitary nucleus
and parbrachial nucleus)
Ventral
Amygdalofugal
Fibers

9. Amygdala Outputs AMYGDALA Septal Nuclei Hypothalamus
Stria Terminalis
Septal Nuclei
Hypothalamus
AMYGDALA
Corticomedial Nuclear
Group
Dorsal Medial Thalamic Nucleus
Nucleus Accumbens
Hypothalamus
Basolateral Nuclear
Group
Central Nucleus
Ventral
Amygdalofugal
Fibers
Nuclei of
ANS
Ventral
Amygdalofugal
Fibers

10. Functions of the Amygdala
Relate environmental stimuli to coordinated behavioral autonomic and endocrine responses seen in species-preservation.
Responses include:
Feeding and drinking
Agnostic (fighting) behavior
Mating and maternal care
Responses to physical or emotional stresses.

11. Limbic System and Basal Nuclei
Anterior Cingulate Gyrus
Orbitofrontal Areas (10, 11)
Medial and lateral temporal lobe
Hippocampus
Amygdala
Entorhinal cortex (24)
Ventral Striatum
(nucleus accumbens)
Caudate Nucleus
(head)
Ventral Anterior Nucleus
Dorsomedial Nucleus
Ventral Pallidum
Medial Globus Pallidus
Pars Reticularis
(Substantia nigra)

12. Papez Circuit (Emotions)
Mammillothalamic
tract
Fornix
Mammillary bodies
Other hypothalamic nuclei
Septal nuclei
Substantia innominata
(Basal nucleus of Meynert)
Hippocampal Formation
(hippocampus
and dentate gyrus)
Anterior Thalamic
nuclear group
Neocortex
Parahippocampal Gyrus
Cortex of Cingulate Gyrus

13. 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

14. 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.