The Limbic System

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The basal ganglia | Main Anatomy Index | The cerebral cortex

Last updated 30 March 2006

The Limbic System

Robinson, S. (1998) The Hippocampal Formation and the Limbic System [Lecture notes]. University of NSW, 12 and 13 October, 1998.

  1. The hippocampal formation;
  2. The cingulate gyrus;
  3. The amygdala;
  4. The septal area;
  5. The mamillary bodies;
  6. The anterior nuclear group of the thalamus;
  7. The inferior temporal lobe;
  8. The prefrontal cortex;
  9. And the tracts that link these areas (e.g., fornix, mammillothalamic tract and stria terminalis).
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The Hippocampal Formation

"the flight of fancy which led Arantius, in 1587, to introduce the term 'hippocampus'.... recorded in what is perhaps the worst anatomical description extant. It has left its readers in doubt whether the elevations of cerebral substance were being compared with fish or beast, and no one could be sure which end was the head." -- Lewis FT.

Gross Anatomy of the Hippocampal Formation

Click here for a diagram of the hippocampal formation.






Hippocampal Sulcus


Fimbriodentate Sulcus


Choroid Fissure

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Histology of the Hippocampal Formation


Molecular Layer


Pyramidal Layer

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Hippocampal Afferents

  1. The most prominent source is the entorhinal cortex. The entorhinal cortex itself receives almost all types of sensory information.
  2. In addition, some septal and hypothalamic fibres reach the hippocampal formation via the fornix.
  3. A few fibres also arrive from the contralateral hippocampal formation passing from one crus to another via the hippocampal commissure.


Hippocampal Efferents

  1. Some turn sharply posteriorly to end in the anterior thalamic nuclei;
  2. The rest travel through the hypothalamus in the column of the fornix and end mainly in the mammillary bodies.
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Functional Aspects of the Hippocampal Formation


Korsakoff's Psychosis

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The Amygdala


Amygdalo-septal Circuit

Click here for a diagram on the stria terminalis.

Click here for a schematic of the amygdalo-septal circuit.


Functional Aspects of the Amygdala


The Septal Area


Functional Aspects of the Septal Area

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Papez's Circuit

Click here for a schematic of Papez's circuit.


Hippocampo-mammillo-cortical Circuit


Clinical Aspects of this Circuit


Clinical Aspects of the Limbic System

Klüver-Bucy Syndrome

  1. The animals are fearless and placid, showing an absence of emotional reactions.
  2. The male animals become hypersexual and are indiscriminate in their choice of sexual partners.
  3. They show in inordinate degree of attention to all sensory stimuli. They respond to every object within sight or reach by sniffing it or examining it orally (consequently leading to hyperphagia).
  4. Although they incessantly examine all objects, they recognise nothing, i.e., they have visual agnosia (due to the loss of the visual association cortex).
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Michael Tam (c) 1998