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Hypothalamus And Limbic System. ANHB 2217 – 2006 Avinash Bharadwaj. Hypothalamus. “Preservation” Feeding Hunger and satiety Defence Somatic and visceral activity Reproduction Sex drive and autonomic responses Homoeostasis Temperature and osmolar regulation.
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Hypothalamus AndLimbic System ANHB 2217 – 2006 Avinash Bharadwaj
Hypothalamus • “Preservation” • Feeding • Hunger and satiety • Defence • Somatic and visceral activity • Reproduction • Sex drive and autonomic responses • Homoeostasis • Temperature and osmolar regulation • A small area with great activity • Crossroads : • Somatic and visceral activity • Emotion and responses • Olfaction, memory and responses • Short- and long control loops
A Medial Zone Posterior Dorsomedial Ventromedial Mamillary body Column of fornix Paraventricular Anterior Supraoptic Pituitary Hypothalamus : Topography
Connections • 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 • Afferent • Somatic and visceral information • Olfactory areas • Emotional / olfactory : amygdaloid nucleus • Hippocampal input via fornix – mamillary body • Cerebral cortex (esp. orbital 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
PV SO P A The Pituitary Connection – 1 • Vasopressin (ADH) • Oxytocin • Large neurons (magnocellular) • Peptides and neurophysins • Herring bodies • Cleavage and release A
P A The Pituitary Connection – 2 • “Adenohypophysis” • Target gland hormone levels… • Small neurones (parvocellular) • Releasing factor (hormone) • Blood vessels • Portal system A
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 Cingulum and cingulate gyrus Fornix Ant nucl thalamus Mamillary body Fornix Ant nucl thalamus Mamillary body Amygdala
Limbic System • Memory • Emotion • “Preservation” • The olfactory connection • Visceral responses Last Slide