Diencephalon Won Taek Lee, M.D., Ph.D.

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

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

* Distance from anterior thalamic pole 15 mm* 12 mm* * Distance from anterior thalamic pole

* Distance from anterior thalamic pole 4.02 mm* 2.02 mm* * Distance from anterior thalamic pole

LATERAL NUCLEAR GROUP Ventral Nuclear Group Ventral Posterior Nucleus (VP) ventral posterolateral nucleus (VPL, V.c.a.e. & V.c.p.e.) - pars oralis (VPLo, VLp) - pars caudalis (VPLc, VPL) ventral posteromedial nucleus (VPM) - pars principalis (VPM, V.c.a.i. & V.c.a.e.) - pars parvocellularis (VPMpc, V.c.pc.i., VMb) ventral posteroinferior nucleus (VPI, V.c.pc.e)

LATERAL NUCLEAR GROUP Ventral Lateral Nucleus (VL) - pars oralis (VLo, V.o.a. VLa) - pars caudalis (VLc, V.o.p., VLp) - pars medialis (VLm, V.o.m. & V.o.i., VMp, VM) Ventral Anterior Nucleus (VA, L.po.) - pars parvicellularis (VApc) - pars magnocellularis (VAmc)

LATERAL NUCLEAR GROUP Ventral Nuclear Group Prefrontal SMA MI, PM SI TTT SNr GPi Cbll ML, STT

LATERAL NUCLEAR GROUP Dorsal or Lateral Nuclear Group Lateral Dorsal Nucleus (LD, D.sf.) Lateral Posterior Nucleus (LP, D.im. & Z.im.) Pulvinar (P, Pu.)

LATERAL NUCLEAR GROUP cingulate gyrus, Somesthetic precuneus Association Area Visual Association area HF SC, Pretectal

MEDIAL NUCLEAR GROUP Dorsomedial Nucleus (MD, M.) - pars magnocellularis, MDmc) - pars parvocellularis, MDpc) - pars paralaminaris (MDpl; pars multiformis, MDmf) - pars densocellularis, MDdc) Midline Nuclear Group Paratenial Nucleus (Pt, Pt.) Reunience Nucleus (Re, Edy.) Submedial Nucleus (Sm) Rhomboid Nucleus (Rh)

ANTERIOR NUCLEAR GROUP anteroventral nucleus (AV, A.pr.) anterodorsal nucleus (AD, A.d.) anteromedial nucleus (AM, A.m.) POSTERIOR NUCLEAR GROUP suprageniculate nucleus (SG, Li.) nucleus limitans (Lim, Li.) posterior nucleus (PO, Li.por.)

MEDIAL & ANTERIOR NUCLEAR GROUP Prefrontal Cortex Frontal Eye Field MB, HF Medial Frontal Gyrus cingulate gyrus Basal forebrain SNr, SC, RF

METATHALAMIC NUCLEAR GROUP Medial Geniculate Nucleus (MG) ventral or principal or parvocellular nucleus (MGv) dorsal nucleus (MGd) medial nucleus (MGm) Lateral Geniculate Nucleus (LG) dorsal nucleus (LGd) ventral nucleus (LGv)

INTRALAMINAR NUCLEAR GROUP Rostral Intralaminar Nuclei central lateral nucleus, CL, i.La.) central medial nucleus, CeM, Co.) paracentral nucleus, PC, i.La.) Caudal Intralaminar Nuclei (CM-PF nuclear complex) centre median nucleus, CM, Ce.) parafascicular nucleus, PF, Pf.)

THALAMIC RETICULAR NUCLEUS Subcortical Structure Cerebral Cortex Thalamocortical Neuron Thalamic Reticular Nucleus Subcortical Structure

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 VPLc ----------- S I, S II 2. Spinothalamic tract VPLc ----------- S I, S II POm ----------- retroinsular cortex Sm ------------- frontal lobe(?) CL ------------- diffuse cortical areas 3. Trigeminothalamic tract VPM ------------- S I, S II

Sensory Input (2) Taste sensation VPM pc ------- gustatory area (Brodmann area 43) (3) Sense of equilibrium VPLo ---------- S I (4) Auditory sensation MGv ----------- A I (Brodmann area 41, 42) MGd ----------- A II (5) Vision LGd ---------- V I (Brodmann area 17) Pi, Pl ---------- V I, V II (Brodmann area 17, 18, 19)

Motor Input (1) Cerebellum (2) Basal ganglia VLc, VPLo, Nucleus X (cell sparse zone) ---------- M I (Brodmann area 4), Premotor area CL ----------- diffuse cortical areas (2) Basal ganglia 1. GPi (internal segment of globus pallidus) VLo -------- SMA (supplementary motor area) VApc ------- frontal cortex CM --------- diffuse cortical areas, striatum, subthalamic nucleus 2. SNr (pars reticularis of substantia nigra) VLm, VAmc - fronal cortex MDpc --------- medial frontal cortex MDpl ---------- frontal eye field (Brodmann area 8)

Reticular Formation & Limbic System rostral intralaminar nuclei (CL, Cem, PC), Rh ----- diffuse cortical areas thalamic reticular nucleus (R), LGv ----- adjacent thalamic nucleus Limbic System Mammillary Body AV, AD, AM ----- cingulate gyrus Hippocampal Formation LD ------------------ cingulate gyrus, precuneus Re ------------------- medial cortex, entorhinal cortex

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)

Visual (Optic) Pathway Modality: Vision Receptor: Photoreceptor Cell of Retina Cranial Nerve: II (Optic nerve) 1st Neuron: Bipolar Cell 2nd Neuron: Ganglion Cell optic nerve optic chiasm optic tract 3rd Neuron: Lateral Geniculate Nucleus optic radiation Termination: Visual Areas (V I, V II) Brodmann area 17 (V I), 18, 19 (V II)

RETINA - Pars Nervosa 1. Pigment Epithelium - retinal detachment 2. Neuronal Layer (1) Photosensitive Cell Layer Rod Cell, Cone Cell (2) Bipolar Cell Layer Bipolar Cell Horizontal Cell Amacrine Cell (3) Ganglion Cell Layer Ganglion Cell Optic Nerve (II)

Visual Pathway 1. Optic nerve 2. Optic chiasm 3. Optic tract 4. Lateral geniculate body 5. Optic radiation 6. Visual cortex

Visual (Optic) Pathway

Visual Pathway Lateral Geniculate Nucleus (LGd) dorsolateral Dorsal Nucleus (LGd) Magnocellular Part 1, 2 Parvocellular Part 3, 4, 5, 6 contralateral afferents 1, 4, 6 ipsilateral afferents 2, 3, 5 Ventral Nucleus (LGv) part of thalamic reticular nucleus ventromedial

Optic Radiation (Geniculocalcarine Tract) Meyer’s loop

Clinical Features of Visual Pathway Lesion 1. optic nerve 2. optic chiasm 3. optic tract 4. 5. optic radiation A. unilateral blindness B. bitemporal hemianopsia C. left homonymous hemianopsia D. left inferior homony- mous quadranopsia E. left superior homony-

Signs of Visual Pathway Lesion Optic nerve - ipsilateral blindness Optic chiasm - bitemporal hemianopsia Optic tract - contralateral homonymous hemianopsia Optic radiation - contralateral homonymous quadranopsia - intact light reflex Visual Cortex - macular sparing

left inferior optic radiation lesion right superior quadranopsia Visual Field Defect left inferior optic radiation lesion right superior quadranopsia

Hypothalamus  Limbic System

Epithalamus  Limbic System Habenular Nucleus Medial Habenular Nucleus Lateral Habenular Nucleus Habenular Commissure Pineal Gland

Subthalamus  Basal Ganglia Subthalamic nucleus zona incerta Field of Forel H ansa lenticularis H1 thalamic fasciculus H2 lenticular fasciculus