LIMBIC SYSTEM History Paul Broca (1824-1880): 1878: le

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LIMBIC SYSTEM
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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)
• 1930s defined a limbic system that might
  underlie the relationship between emotion and
  memory (Papez circuit).

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Components

• Amygdaloid body
• Hippocampus (seahorse)
• Cingulate gyus
• Parahippocampal gyrus
• Hypothalamus
• Mamillary bodies
• Anterior nucleus of thalamus

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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

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Amygdala

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

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

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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
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Amygdala Outputs
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
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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.

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

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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.