THE LIMBIC SYSTEM

By:Amuthameena A/P Manoharan

Jayaganthan A/L MaunagarThiaggu A/L PalanMuhammad Zahir B. Mohd Sabri

HIGHLIGHTS

•Definition•Anatomical structures•Connecting pathways•Afferent connections of the hippocampus•Efferent conections of the hippocampus•Functions

The Limbic System

•Used to include a group of structures that lie in the border zone between the cerebral cortex and the hypothalamus.

•Controls behaviour, emotion, and drive; also appears to be important to memory.

Anatomical Structures

•Subcallosal•Cingulate gyrus•Parahippocampal gyrus•Hippocampal formation•Amygdaloid nucleus•Mamillary bodies•Anterior thalamic nucleus

Connecting Pathways

•Alveus•Fimbria•Fornix•Mammillothalamic tract•Stria terminalis

Afferent Connections of the Hippocampus1. Cingulate gyrus pass to the hippocampus.

2. Septal nuclei (nuclei lying within the midline close to the anterior commissure) pass posterior in the fornix to the hippocampus

3. One hippocampus pass across the midline to the opposite hippocampus in the commissure of the fornix.

4. Indisium griseum pass posteriorly in the longitudinal striae to the hippocampus.

5. Entorhinal area or olfactory-associated cortex pass to the hippocampus.

6. Dentate and parahippocampalgyri travel to the hippocampus.

Efferent Connections of the Hippocampus

1. Posterior to the anterior commissure to enter the mammillary body, end in the medial nucleus.

2. To end in the anterior nuclei of the thalamus.

3. To enter the tegmentum of the midbrain

4. To end in the septal nuclei, the lateral preoptic area, and the anterior par of the hypothalamus.

5. Fibers join the stria medullaris thalami to reach the habenular nuclei.

Functions of the Limbic System

•Control the endocrine system; able to influence many aspects of emotional behaviour (fear, anger, sexual, etc.).

•Converting recent memory to long-term memory

•Integration and effective homeostatic responses to a wide variety of environmental stimuli.

Clinical Notes on The Limbic System

• SCHIZOPHRENIA- include chronically disordered thinking, blunted effect and emotional

withdrawal.- paranoid delusions and auditory hallucinations may also be present.

• DESTRUCTION of the AMYGDALOID COMPLEX- decreased aggressiveness, emotional instability and restlessness; increased

interest in food and hypersexuality.- Kluver-Bucy Syndrome

• TEMPORAL LOBE DYSFUNCTION- preceded by an aura of acoustic or olfactory experience.- often confused, anxious, and docile.- May perform automatic and complicated movements; and then have no

memory of what occurred previously.

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