Hypothalamus And

Limbic System

ANHB 2217 – 2006

Avinash Bharadwaj

Hypothalamus A small area with great

activity Crossroads :

Somatic and visceral activity Emotion and responses Olfaction, memory and

responses Short- and long control loops

“Preservation” Feeding

Hunger and satiety Defence

Somatic and visceral activity

Reproduction Sex drive and autonomic

responses Homoeostasis

Temperature and osmolar regulation

Hypothalamus : Topography

A

Column of fornix

Paraventricular

Anterior

Supraoptic

Posterior

Dorsomedial

Ventromedial

Mamillary body

Medial Zone

Pituitary

Connections Afferent Somatic and visceral

information Olfactory areas Emotional / olfactory :

amygdaloid nucleus Hippocampal input

via fornix – mamillary body

Cerebral cortex (esp. orbital cortex

Efferent Autonomic nuclei –

brainstem, spinal cord Striated muscle :

Brainstem + Spinal motor neurons (feeding / shivering…)

Mamillary body thalamus cingulate gyrus – memory, visceral expression of emotion

Mamillary body brainstem reticular formation

? Higher mental function through cortex

Problems in Studying… Indistinct nuclear boundaries Tracts and nuclei – crisscross Imprecise experimental / clinical lesions

Some Functional Correlations Clinical / experimental Anterior / preoptic : parasympathetic Posterior / lateral : sympathetic

Temperature sensors – vasodilation and sweating OR constriction and shivering.

Hunger and satiety centres : blood glucose, visceral afferents, smell, limbic inputs

Intrinsic sensors

The Pituitary Connection – 1

Vasopressin (ADH) Oxytocin

Large neurons (magnocellular) Peptides and neurophysins Herring bodies Cleavage and release

A

PV

SO

A P

The Pituitary Connection – 2

“Adenohypophysis” Target gland hormone levels… Small neurones (parvocellular) Releasing factor (hormone) Blood vessels

Portal systemA

A P

Summary

Weaving together Autonomic and

endocrine controls Homeostasis Higher centres

Limbic System

Limbic lobe and limbic system “Limbus” Lobe : hippocampus, PHG, cingulate gyrus System : Also includes

Dentate gyrus, amygdaloid, septal area, mamillary bodies, thalamic nuclei

Limbic System

Hippocampus

Dentate gyrus

Parahippocampal gyrus

Fornix

Ant nucl thalamus

Mamillary body

Fornix

Ant nucl thalamus

Mamillary body

Cingulum and cingulate gyrus

Amygdala

Hippocampus

Limbic System

Memory Emotion “Preservation” The olfactory connection Visceral responses

Last Slide