Hypothalamus, Limbic, Olfactory and Gustatory System Andres S. Javier MD

Assistant ProfessorDepartment of Anatomy

College of MedicineUERMMMCI

Limbic System

Olfactory System

Gustatory System

Hypothalamus

Hypothalamus, Limbic, Olfactory and Gustatory System Objectives

To give an introduction of the HypothalamusTo describe the Hypothalamus by

A. Locating its regions and its boundariesB. Descrbing the hypothalamic regions and the respective nucleiC. Tracing principal afferent and efferent connections

Hypothalamus

Limbic System

Olfactory System

Gustatory System

Hypothalamus

Hypothalamus, Limbic, Olfactory and Gustatory System Objectives

D. Enumerating the functions of the hypothalamusE. Describing the hypophyseal portal system and its role in the endocrine functionF. Naming the major hypothalamic hormones and giving their functions and source

Hypothalamus

Hypothalamus |Introduction

head ganglion of the ANS subdivision of the diencephalon weighs 4g and forms <1% of the brains total weightintegrates functions of endocrine, autonomic(visceral motor), somatic motor and limbic systemconsists of group of nuclei each playing a role in homeostasis

Hypothalamus |Introduction

crucial to the survival of the organismControl of appetiteFluid balanceElectrolyte balanceGlucose concentrationMetabolism,Sleeping Role in sexual behavior

Hypothalamus |Boundaries

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Hypothalamus |Boundaries

Hypothalamus |Boundaries

Hypothalamus |Boundaries

Structure

Rostral (Anterior) Anterior Commisure

Lamina Terminalis

Optic ChiasmaCaudal(Posterior) Mamillary BodySuperiorly Interventricular foramen Inferiorly Floor of the third ventricleMedial Third Ventricle Lateral Internal capsule

Subthalmic nucleus

Substantia innominata

Hypothalamus | Zones and Regions

ZONESPeriventricularMedialLateral

REGIONSPreopticAnteriorMiddlePosterior

Hypothalamus |Regions of Hypothalamic Nuclei

Hypothalamus |Zones

Periventricular

Suprachiasmatic nucleus

Paraventricular nucleus

Arcuate (infindibular) nucleus

Hypothalamus | Medial zone/Medial hypothalamic area

Middle orTuberal region

Dorsomedial nucleusVentromedial nucleusInfindibular (arcuate) nucleus

Posterior or Mamillary region Posterior nucleus Mammillary

nucleus

Lateral nucleus Preoptic nucleus Suprachiasmatic

nucleus Supraoptic

nucleus Tuberomammillary

nucleus

Hypothalamus | Lateral zone/Lateral Hypothalamic area

Hypothalamus |Regions of Hypothalamic Nuclei

Hypothalamus | Notes on Zones and Regions

Nuclei such as the:

PREOPTIC NUCLEUS, SUPRACHIASMATIC NUCLEUS and PARAVENTRICULAR NUCLEI overlap zones

Hypothalamus |Afferent Connections

Hypothalamus |Afferent Connections Pathway Origin Destination

Medial and spinal lemnisci, tractus solitarius, reticular formation

Viscera and somatic structures

Hypothalamic nuclei

Visual fibers Retina Suprachiasmatic nucleus

Medial forebrain bundle Olfactory mucous membrane

Hypothalamic nuclei

Auditory fibers Inner ear Hypothalamic nuclei

Corticohypothalamic fibers Frontal lobe of cerebral cortex

Hypothalamic nuclei

Hippocampohypothalamic fibers Hippocampus Hippocampus Nuclei of mammillary body

Amygdalohypothalamic fibers Amygdaloid complex Hypothalamic nuclei

Thalamohypothalamic fibers Dorsomedial and midline nuclei of thalamus

Hypothalamic nuclei

Tegmental fibers Tegmentum of midbrain Hypothalamic nuclei

Hypothalamus |Efferent Connections

Hypothalamus |Efferent Connections Pathway Origin Destination

Descending fibers in reticular formation to brainstem and spinal cord

Preoptic, anterior, posterior, and lateral nuclei of hypothalamus

Craniosacral parasympathetic and thoracolumbar sympathetic outflows

Mammillothalamic tract Nuclei of mammillary body Anterior nucleus of thalamus; relayed to cingulate gyrus

Mammillotegmental tract Nuclei of mammillary body Reticular formation in tegmentum of midbrain

Multiple pathways Hypothalamic nuclei Limbic system

Hypothalamus | Connections with the Hypophysis Cerebri

Connected by two pathways:

Nerve fibers that travel from the supraoptic and paraventricular nuclei to the posterior lobe of the hypophysis

Long and short portal blood vessels that connect sinusoids in the median eminence and infundibulum with capillary plexuses in the anterior lobe of the hypophysis

Hypothalamus |Connections of the Hypothalamus With the Hypophysis Cerebri

Hypothalamic Regulatory Hormone Anterior Pituitary Hormone Functional Result

Growth hormone–releasing hormone (GHRH)

Growth hormone (GH) Stimulates linear growth in epiphyseal cartilages

Growth hormone–inhibiting hormone (GHIH) or somatostatin

Growth hormone (reduced production)

Reduces linear growth in epiphyseal cartilages

Prolactin-releasing hormone (PRH)

Prolactin (luteotropic hormone, LTH)

Stimulates lactogenesis

Prolactin-inhibiting hormone (PIH), dopamine

Prolactin (luteotropic hormone, LTH) (reduced production)

Reduces lactogenesis

Corticotropin-releasing hormone (CRH)

Adrenocorticotropic hormone (ACTH)

Stimulates adrenal gland to produce corticosteroids and sex hormones

Thyrotropin-releasing hormone (TRH)

Thyroid-stimulating hormone (TSH)

Stimulates thyroid gland to produce thyroxine

Luteinizing hormone–releasing hormone (LHRH), ? follicle-stimulating releasing hormone (FRH)

Luteinizing hormone (LH) and follicle-stimulating hormone (FSH)

Stimulates ovarian follicles and production of estrogen and progesterone

Hypothalamic Regulatory Hormone Origin

Growth hormone–releasing hormone (GHRH)

Infundibular or arcuate nucleus

Growth hormone–inhibiting hormone (GHIH) or somatostatin

Suprachiasmatic nucleus

Prolactin-releasing hormone (PRH) ?

Prolactin-inhibiting hormone (PIH), dopamine

?

Corticotropin-releasing hormone (CRH) Paraventricular nuclei

Thyrotropin-releasing hormone (TRH) Paraventricular and dorsomedial nuclei and adjacent areas

Luteinizing hormone–releasing hormone (LHRH)

Preoptic and anterior nuclei

Hypothalamus | Functions

AUTONOMIC CONTROL

Basic Functions:1. Regulation and control of certain

aspects of visceral activity, particularly those affected by the ANS and pituitary gland

2. Control of the motor activity, both somatic and visceral, of emotional perceptions

Hypothalamus | Functions

AUTONOMIC CONTROL

Anterior and preoptic area - influence parasympathetic responses

Posterior and lateral nuclei - stimulation causes sympathetic responses

Hypothalamus | Functions

ENDOCRINE CONTROL

Paraventricular nuclei• OxytocinSupraoptic nuclei• Anti-diuretic hormone (ADH) or

vasopressin- hypothalamo-hypohyseal tractArcuate and ventromedial nuclei (Medial

Zone)• releasing hormones/ inhibitory releasing

hormones- hypothalamo-hypophyseal portal vessels

Hypothalamus | Functions

TEMPERATURE CONTROL

Anterior hypothalamic area - HEAT LOSS CENTER

– controls mechanism that dissipate heat loss >> cutaneous vasodilatation and sweating >> decreased body temperature

Lesion: hyperthermia

Hypothalamus | Functions

TEMPERATURE CONTROL

Posterior hypothalamic area – HEAT GAIN CENTER

- stimulation causes vasoconstriction of skin blood vessels and inhibition of sweating>> peripheral vasoconstriction and shivering >> increased body temp

Lesion: hypothermia

Hypothalamus | Functions

REGULATION OF FOOD AND WATER INTAKE

Lesion: Anorexia

Lateral region – HUNGER OR FEEDING CENTER (initiates

feeling of hunger)Medial/Ventromedial region – SATIETY CENTER (inhibits eating)Lateral region – THIRST CENTER (increase in the desire to

drink)

Lesion: Uncontrolled Voracious appetite

Hypothalamus | Functions

Hypothalamus | Functions

EMOTION AND BEHAVIOR

Hypothalamus Limbic systemPrefrontal cortex

Lateral nuclei – stimulation may cause signs and symptoms of

rage and hyperactivity (lesion: passivity)Ventromedial nuclei – stimulation may cause passivity ( lesion: rage)

Hypothalamus | Functions

CONTROL OF CIRCADIAN RHYTHM(Sleep-wakefulness regulation)

ThalamusLimbic systemReticular activating systemHypothalamus Suprachiasmatic nucleus - via connections with ARAS Lesion of anterior part of hypothalamus-interfere

with rhythm of sleeping and waking Lesion of dorsolateral mammillary region-produce

somnolence

Hypothalamus |Functions of the Main Hypothalamic Nuclei Hypothalamic Nucleus Presumed Function

Supraoptic nucleus Synthesizes vasopressin (antidiuretic hormone)

Paraventricular nucleus Synthesizes oxytocin

Preoptic and anterior nuclei Control parasympathetic system

Posterior and lateral nuclei Control sympathetic system

Anterior hypothalamic nuclei Regulate temperature (response to heat)

Posterior hypothalamic nuclei Regulate temperature (response to cold)

Lateral hypothalamic nuclei Initiate eating and increase food intake (hunger center)

Medial hypothalamic nuclei Inhibit eating and reduce food intake (satiety center)

Lateral hypothalamic nuclei Increase water intake (thirst center)

Suprachiasmatic nucleus Controls circadian rhythms

Limbic System

Olfactory System

Gustatory System

Hypothalamus

Hypothalamus, Limbic, Olfactory and Gustatory System End

To give an introduction of the HypothalamusTo describe the Hypothalamus by

A. Locating its regions and its boundariesB. Descrbing the hypothalamic regions and the respective nucleiC. Tracing principal afferent and efferent connections

Hypothalamus

Limbic System

Olfactory System

Gustatory System

Hypothalamus

Hypothalamus, Limbic, Olfactory and Gustatory System End

D. Enumerating the functions of the hypothalamusE. Describing the hypophyseal portal system and its role in the endocrine functionF. Naming the major hypothalamic hormones and giving their functions and source

Hypothalamus

Limbic System

Olfactory System

Gustatory System

Hypothalamus

Hypothalamus, Limbic, Olfactory and Gustatory System Objectives

To give an introduction of the Limbic SystemTo demonstrate knowledge and understanding of the limbic system by

A.Identifying the structures that comprise the limbic systemB.Enumerating the sources of input and output of the limbic systemC.Describing the major circuit of the limbic system (Papez Circuit)D. Naming disorders involved

Limbic System

Limbic System |Introduction

Limbic (“border”) Systemconsists of a diverse group of structures that would include phylogenetically ancient cortical areas a group of associated subcortical nuclei as well as associated pathways that interconnect regions of the telencephalon, diencephalon and brainstemmodulates hypothalamus whereby influencing functions of endocrine and the ANS

Limbic System |Introduction

Limbic (“border”) SystemFunctions

species preservation self preservation expression of fear, motivation, as well as

memory and learning Structures

AmygdaloidCingulateHippocampal formationMamillary BodiesParahippocampal formationSubcallosalAnterior thalamic nucleus

Limbic System |Hippocampal Formation

Hippocampal FormationIncludes:

HIPPOCAMPUS PROPER (Ammon’s horn/Cornu ammonis)

DENTATE GYRUS PARAHIPPOCAMPAL GYRUS

involved in the consolidation of short-memory into long term memory

Limbic System |Structures

Hippocampal Formation |

Hippocampal Formation |

Hippocampal Formation |

Hippocampal Formation

Hippocampal Formation

Hippocampal Formation and Amygdaloid

Structure |Hippocampal Functions

Hippocampal FormationBoth morphological and functional evidence support the thesis that the hippocampus has no direct relationship with the sense of smell

The hippocampus maybe concerned with recent memory

The hippocampal formation appears to have a role in the expression of emotion

Structure |Functional Significance of the Amygdaloid

Amygdaloid Olfactory senseFear and Anger ResponsesVisceral and Autonomic responsesSomatic ResponsesEndocrine Responses

Structure |Hippocampus and Dentate Group

Points

Cortical structure of the parahippocampal gyrus is six-layered Gradual transition from a six --> three layers as cortex is traced into the hippocampus

MOLECULAR PYRAMIDALPOLYMORPHIC

Dentate gyrus also has three layers, but pyramidal is replaced by GRANULAR

Layers|

Connecting Pathways | Limbic System

Components

ALVEUSFIMBRIAFORNIXMAMMILOTHALAMIC TRACTSTRIA TERMINALIS

Connecting Pathways | Limbic System

Connecting Pathways | Limbic System

Limbic System |Afferent and Efferent Connections

Fibers arising in the CINGULATE GYRUS SEPTAL NUCLEI(nuclei lying within the midline close to the anterior commissure)

pass posterior in the fornix HIPPOCAMPUS pass across the midline to the opposite hippocampus in the commissure of the fornix. INDUSIUM GRISEUM pass posteriorly in

the longitudinal striae ENTORHINAL AREA DENTATE AND PARAHIPPOCAMPAL GYRI

Limbic System |Afferent Connections of the Hippocampus

Fibers pass posterior to the anterior commissure enter the MAMMILLARY BODY, and end in

the MEDIAL NUCLEUS to end in ANTERIOR NUCLEI of the thalamus to enter TEGMENTUM of the midbrain

Fibers pass anterior to the anterior commissure to end in the SEPTAL NUCLEI. LATERAL

PREOPTIC AREA and ANTERIOR PART OF HYPOTHALAMUS

Fibers join the stria medullaris thalami to reach the HABENULAR NUCLEI

Limbic System |Efferent Connections of the hippocampus

Limbic System |Papez Circuit

Hippocampus Alveus Fimbrae Fornix Mamillary bodies Anterior nucleus of thalamus Cingulate gyrus Entorhinal cortex back to Hippocampus

Korsakoff’s psychosisAlzheimer’s diseaseHippocampal ablationAnterograde Amnesia

Disorders of the Limbic System

Limbic System

Olfactory System

Gustatory System

Hypothalamus

Hypothalamus, Limbic, Olfactory and Gustatory System End

To give an introduction of the Limbic SystemTo demonstrate knowledge and understanding of the limbic system by

A.Identifying the structures that comprise the limbic systemB.Enumerating the sources of input and output of the limbic systemC.Describing the major circuit of the limbic system (Papez Circuit)D. Naming disorders involved

Limbic System

BREAK FOR

5 MINUTES

Limbic System

Olfactory System

Gustatory System

Hypothalamus

Hypothalamus, Limbic, Olfactory and Gustatory System Objectives

To give an introduction of the Olfactory SystemDemonstrate knowledge and understanding of the pathways for olfaction by

A.Enumerating the structures that comprise the rhinencephalonB.Stating the receptors for smellC.Tracing the olfactory pathwaysD. Naming some clinical disorders involving olfactory pathways

Olfactory System

RHINENCEPHALON “nose brain” Oldest part of the cerebrum

phylogenetically Has been since subordinated in man to

non-olfactory portions of cerebrum “macrosmatic” vs “microsmatic” Odors generate complex associations of

ideas, images and personal interpretations modified by past experiences

ACTIVATOR and SENSTIZER of other neural systems

Olfactory System | Introduction

RHINENCEPHALON Includes structres that are believed to be

concerned with smell:

OLFACTORY NERVE OLFACTORY BULB OLFACTORY TRACT OLFACTORY STRIAE (medial,

intermediate, and lateral) ANTERIOR OLFACTORY

NUCLEUS(within olfactory bulb, tract and striae)

Olfactory System | Introduction

RHINENCEPHALON Includes structres that are believed to be

concerned with smell: ANTERIOR PERFORATED SUBSTANCE SUBCALLOSAL( or paraolfactory area) ANTERIOR PORTIONS OF THE

PARAHIPPOCAMPAL AREA(including uncus)

HIPPOCAMPAL FORMATION(beneath parahippocampal gyrus)

PREPYRIFORM CORTEX (extending from the olfactory stria to the rostral amygdaloid region)

AMYGDALOID COMPLEX(part)

Olfactory System | Introduction

Olfactory System

Olfactory System

Olfactory System

Olfactory System

Primary Olfactory Cortex – (Area 34)

a. Prepiriform/ Piriform areasb. Periamygdaloid

Secondary Olfactory Cortex – (Area 28)a. Entorrhinal area- association cortex for olfaction; site of overlap between limbic and olfactory systems

* Olfactory afferent pathway – projects directly into the cerebral cortex

Olfactory System | Cortex

Connections are numerous and complex

Pathways for triggering autonomic responses Via the MEDIAL

FOREBRAIN BUNDLE Via STRIA MEDULLARIS Via LIMBIC SYSTEM

Olfactory System | Reflexes

Primary sensory neurons in olfactory epithelium Pass through cribriform plate Synapse on secondary neurons in the olfactory bulb(mitral and tufted cells) Tufted cells synapse in the anterior olfactory nucleus and send projects to all olfactory areas

Mitral cells send collaterals to the anterior olfactory nucleus and project only to the lateral olfactory area Olfactory tract Olfactory trigone Olfactory stria

Olfactory System | Pathway

Medial - Projects to the frontal lobe(medial

olfactory area)- Mediates emotional response to odors and

has connections to the limbic systemIntermediate- Projects to the anterior perforated

substanceLateral- Projects to lateral olfactory area- Important ConnectionsLOS Stria Medullaris HabenulaLOS Pyriform Lobe, prepyriform cortex,

periamygdaloid area, uncus, insula(Primary olfactory complex) Entorhinal complex

Olfactory System | Olfactory Stria

Anosmia CSF Rhinorrhea

Olfactory System | Disorders

Limbic System

Olfactory System

Gustatory System

Hypothalamus

Hypothalamus, Limbic, Olfactory and Gustatory System End

To give an introduction of the Olfactory SystemDemonstrate knowledge and understanding of the pathways for olfaction by

A.Enumerating the structures that comprise the rhinencephalonB.Stating the receptors for smellC.Tracing the olfactory pathwaysD. Naming some clinical disorders involving olfactory pathways

Olfactory System

Limbic System

Olfactory System

Gustatory System

Hypothalamus

Hypothalamus, Limbic, Olfactory and Gustatory System Objectives

Demonstrate knowledge and understanding of the pathway for taste sensation by

A.Describing the receptor for tasteB.Naming the cranial nerves that subserve taste sensationC.Tracing the pathway for taste

Gustatory System

Gustatory System |Taste Receptors

Gustatory System |Taste Receptors

Gustatory System |Afferent Innervation for Taste Sensation

Gustatory System |Taste Pathway

Gustatory System |General Visceral Afferent Innervation

Limbic System

Olfactory System

Gustatory System

Hypothalamus

Hypothalamus, Limbic, Olfactory and Gustatory System End

Demonstrate knowledge and understanding of the pathway for taste sensation by

A.Describing the receptor for tasteB.Naming the cranial nerves that subserve taste sensationC.Tracing the pathway for taste

Gustatory System

ReferencesSnell, R.S. Clinical Neuroanatomy, 7th ed., Lippincott

Williams & Wilkins, 2010.Carague-Lansang, E.N., et al. Lansang Notes: Modules

in Neuroanatomy, 4th ed., UERMMMC: Quezon City, 2006.

Blumenfeld, H. Neuroanatomy through Clinical Cases, 2nd ed., Sinauer Associates, Inc., 2010.

Fisch, A. Neuroanatomy Draw It to Know It, 1st ed., Oxford University Press, 2009.

Netter, F. Atlas of Neuroanatomy and Neurophysiology, 1st ed.,Icon Custom Communication, 2002.

Junquiera, L.C., and Carneiro, J. Basic Histology Text and Atlas, 11th ed., McGraw-Hill Companies. 2007

Patestas, M.A. and Gartner L.P. A Textbook on Neuroanatomy, 1st ed., Blackwell Publishing, 2006

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