Diencephalon

Diencephalon

• Thalamus dorsal thalamus

• Hypothalamus

pituitary gland

• Epithalamus

habenular nucleus and commissure

pineal gland

• Subthalamus ventral thalamus

subthalamic nucleus (STN)

field of Forel

Diencephalon

dorsal surface

Diencephalon

ventral surface

Diencephalon

Medial Surface

THALAMUS

Function of the Thalamus

• Sensory relay – ALL sensory information

(except smell)

• Motor integration – Input from cortex, cerebellum

and basal ganglia

• Arousal – Part of reticular activating

system

• Pain modulation – All nociceptive information

• Memory & behavior – Lesions are disruptive

Classification of Thalamic Nuclei

I. Lateral Nuclear Group

II. Medial Nuclear Group

III. Anterior Nuclear Group

IV. Posterior Nuclear Group

V. Metathalamic Nuclear Group

VI. Intralaminar Nuclear Group

VII. Thalamic Reticular Nucleus

Classification of Thalamic Nuclei

LATERAL NUCLEAR GROUP

Ventral Nuclear Group

Ventral Posterior Nucleus (VP)

ventral posterolateral nucleus (VPL) ventral posteromedial nucleus (VPM)

Input to the Thalamus

Sensory relay - Ventral posterior group all sensation from body and head,

including pain

Projections from the Thalamus

Sensory relay Ventral posterior group

all sensation from body and

head, including pain

LATERAL NUCLEAR GROUP

Ventral Lateral Nucleus

Ventral Anterior Nucleus

Input to the Thalamus

Motor control and integration

Projections from the Thalamus

Motor control and integration

LATERAL NUCLEAR GROUP

Ventral Nuclear Group

TTT

ML, STT Cbll GPi

SNr

Prefrontal SMA MI, PM SI

Lateral Dorsal Nuclear Group

Lateral Dorsal Nucleus

Lateral Posterior Nucleus

Pulvinar

LATERAL NUCLEAR GROUP

SC, Pretectal

HF

Visual

Association

area

Somesthetic

Association

Area

cingulate gyrus,

precuneus

MEDIAL NUCLEAR GROUP

Dorsomedial Nucleus (MD) - pars magnocellularis - pars parvocellularis

Midline Nuclear Group

Input to the Thalamus

Behavior and emotion connection with hypothalamus

Projections from the Thalamus

Behavior and emotion connection with hypothalamus

MEDIAL & ANTERIOR NUCLEAR GROUP

MB, HF

Prefrontal

Cortex Frontal

Eye Field Medial

Frontal

Gyrus

cingulate

gyrus Basal

forebrain SNr, SC, RF

METATHALAMIC NUCLEAR GROUP

Medial Geniculate Nucleus (MG)

ventral nucleus

dorsal nucleus

medial nucleus

Lateral Geniculate Nucleus (LG)

dorsal nucleus

ventral nucleus

Input to the Thalamus

Metathalamus Vision and Hearing

Projections from the Thalamus

Metathalamus Vision and Hearing

INTRALAMINAR NUCLEAR GROUP

Rostral Intralaminar Nuclei

central lateral nucleus,

central medial nucleus,

paracentral nucleus,

Caudal Intralaminar Nuclei

centro-median nucleus

THALAMIC RETICULAR NUCLEUS

Cerebral Cortex

Subcortical Structure

Thalamic

Reticular

Nucleus

Thalamocortical

Neuron

Summary of Thalamic Connectivity

I. Sensory Input

general sensation

special sensation

taste, equilibrium, hearing, vision

II. Motor Input

cerebellum, basal ganglia

III. Reticular Formation

IV. Limbic System

mammillary nucleus

hippocampal formation

Sensory Input

(1) General Sensation

1. Medial lemniscus - VPL

2. Spinothalamic tract - VPL

3. Trigeminothalamic tract – VPM

(2) Taste sensation - VPM

(3) Sense of equilibrium - VPL

(4) Auditory sensation - MG

(5) Vision - LG

Motor Input

(1) Cerebellum

VL, VPL,

(2) Basal ganglia

1. GPi

2. SNr

Reticular Formation & Limbic System

Reticular formation

rostral intralaminar nuclei

thalamic reticular nucleus

Limbic System

Mammillary Body - AN

Hippocampal Formation - AN

Clinical Syndromes of the Thalamus

Posterolateral thalamic syndromes

sensory disorders

Thalamic (Dejerine-Roussy) syndrome

----- VP nucleus - pain Medial thalamic syndromes

disorders of consciousness

thalamic neglect, thalamic amnesia,

akinetic mutism Anterolateral thalamic syndromes

motor disorders

paresis, ataxia, motor incoordination, dysphagia

Thalamic (Dejerine-Roussy) Syndrome

Joseph Jules Dejerine

(1849-1917)

Gustave Roussy

(1874-1948)

Epithalamus Limbic System

Habenular Nucleus

Medial Habenular Nucleus

Lateral Habenular Nucleus

Habenular Commissure

Pineal Gland

Epithalamus

Corpus pineale

Trigonum & commissura habenulae

Stria medullaris thalami

Commissura posterior

Tela choroidea & plexus choroideus of 3rd ventricle

Epithalamus

1. Trigonum habenulae

Small nuclei habenulae, above commissura posterior.

3 connections:

– Stria medullaris thalami – afferents to nuclei habenulae

mainly from area septalis

– Commissura habenularum – btwn trigonum habenulae

– Tractus habenulointerpeduncularis (fasciculus

retroflexus) – efferents to nucl. interpeduncularis, RF,

substantia grisea centralis

2. Functions of nuclei habenulae

Vague. Supposed to mediate olfactory stimuli and

feeding behavior. Connect olfactory brain,

hypothalamus and limbic system with brain stem.

3. Corpus pineale

Produces melatonin and serotonin. Controls circadian

rhythms, reprductive cycles and maturation (puberty)

Subthalamus Basal Ganglia

Subthalamic nucleus

zona incerta

Field of Forel

H ansa lenticularis

H1 thalamic fasciculus

H2 lenticular fasciculus