1. Principles of neural organization
2. Spinal cord
3. Brainstem medulla oblongata pons midbrain
4. Cerebellum
5. Forebrain diencephalon, hypothalamus cerebrum

nerve cells (neurons) – at least 10 billion cell body (perikaryon, soma) axon – myelinated or unmyelinated dendrites glial cells (neuroglia): astrocytes oligodendrocytes, Schwann cells microglia ependymal cells less than 1 mm to more than 1 m in length
2 Prof. Dr. Nikolai Lazarov

Prof. Dr. Nikolai Lazarov 3

encephalon (brain): telencephalon (‘endbrain’) diencephalon
(‘between brain’) mesencephalon
(midbrain) pons cerebellum medulla oblongata spinal cord functional parts: cerebrum brain stem cerebellum
Prof. Dr. Nikolai Lazarov 4

Spinal cord
topography and levels – in the vertebral canal fetal life – the entire length of vertebral canal at birth – near the level L3 vertebra adult – upper ⅔ of vertebral canal (L1-L2) average length:
♂ – 45 cm long
♀ – 42-43 cm diameter ~ 1-1.5 cm (out of enlargements) weight ~ 35 g (2% of the CNS) shape
– round to oval (cylindrical) terminal part: conus medullaris filum terminale internum
(cranial 15 cm) – S2 filum terminale externum
(final 5 cm) – Co2 cauda equina – collection of lumbar and sacral spinal nerve roots
5 Prof. Dr. Nikolai Lazarov

Spinal cord
cervical enlargement, intumescentia cervicalis: spinal segments (C4-Th1) vertebral levels (C4-Th1) provides upper limb innervation
(brachial plexus) lumbosacral enlargement, intumescentia lumbosacralis: spinal segments (L2-S3) vertebral levels (Th9-Th12) segmental innervation of lower limb
(lumbosacral plexus)
6 Prof. Dr. Nikolai Lazarov

Spinal cord
Two symmetrical halves: divided by two external longitudinal grooves: a deeper anterior median fissure a shallower posterior median sulcus (less prominent) joined by a commissural band of nervous tissue
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Prof. Dr. Nikolai Lazarov
Spinal cord
31 segments:
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal segment ≠ vertebra: growth of the vertebral column exceeds that of the spinal cord all segments terminate above level L1/L2 cauda equina vary in diameter and length
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Spinal cord
grey matter, substantia grisea butterfly-like or H-shaped white matter, substantia alba vary in diameter and length at different levels
9 Prof. Dr. Nikolai Lazarov

Spinal cord
composition: neuronal perikarya dendrites with their synapses glial supporting cells blood vessels anterior (ventral) column: cornu anterius (columna anterior) posterior (dorsal) column: cornu posterius
(columna posterior) lateral column: cornu laterale – Th1-L2; S2-S4
(columna intermedia) central canal: canalis centralis liquor cerebrospinalis substantia gelatinosa centralis grey commissure: commissura grisea
10 Prof. Dr. Nikolai Lazarov

Spinal cord
posterior column (dorsal horn): apex, caput, cervix, basis projection neurons ( neurocyti funiculares ) and interneurons (neurocyti interni) lateral column
( intermediolateral horn ) : visceromotor neurons parasympathetic sympathetic anterior column (ventral horn): motor neurons ( neurocyti radiculares ) large alpha motoneurons (ACh) small gamma motoneurons (ACh)
Renshaw cells
(inhibitory interneurons)
(Gly)
11 Prof. Dr. Nikolai Lazarov

Spinal cord
composition: nerve fibers glia blood vessels
■
3 columns (funiculi)
– ascending and descending tracts posterior funiculus: funiculus dorsalis (posterior) lateral funiculus: funiculus lateralis
Prof. Dr. Nikolai Lazarov anterior funiculus: funiculus ventralis (anterior)
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Spinal cord
reflex arc – the neural pathway that mediates a reflex action two types of reflex arcs: autonomic reflex arc (affecting inner organs) somatic reflex arc (affecting muscles) monosynaptic vs. polysynaptic reflex arcs
Prof. Dr. Nikolai Lazarov
‘Final common path(way)’ (of Sherrington)
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Spinal cord
Prof. Dr. Nikolai Lazarov 14

Spinal cord three meninges: dura mater epidural and subdural spaces arachnoid mater subarachnoid space cerebrospinal fluid (liquor) pia mater (leptomeninges) perivascular spaces spinal blood vessels
15 Prof. Dr. Nikolai Lazarov

Brain stem
3 subdivisions: medulla oblongata pons midbrain
10 cranial nerves attached
(with the exception of nn . I and II) motor and sensory innervation: face&neck pathway for: all fiber tracts passing up and down
3 laminae: tectum, tegmentum, basis neurological functions: survival breathing digestion heart rate blood pressure arousal being awake and alert
16 Prof. Dr. Nikolai Lazarov

Medulla oblongata
synonyms: bulbus, myelencephalon shape
– pyramidal or conical size:
3 cm longitudinally
2 cm transversally
1.25 cm anteroposteriorly
2 parts: lower, closed part upper, open part functions: relay station of motor tracts contains respiratory, vasomotor and cardiac centers controls reflex activities such as coughing, gagging, swallowing and vomiting
17 Prof. Dr. Nikolai Lazarov

Medulla oblongata
anterior median fissure pyramid pyramidal decussation olive anterolateral sulcus hypoglossal nerve (XII) retroolivar sulcus nn. IX, X and XI
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Medulla oblongata
posterior median sulcus caudal, closed part – obex: gracile fascicle gracile tubercle cuneate fascicle cuneate tubercle posterior intermediate sulcus posterolateral sulcus trigeminal tubercle tuberculum cinereum
19 Prof. Dr. Nikolai Lazarov

Medulla oblongata
cranial, open part – rhomboid fossa: medullary striae of fourth ventricle obex sulcus limitans hypoglossus triangle vagus triangle area postrema vestibular area, acoustic tubercle pons inferior cerebellar peduncle cerebellum
20 Prof. Dr. Nikolai Lazarov

Medulla oblongata
white and grey matter olive: inferior olivary nuclear complex posterior column nuclei: nucleus gracilis nucleus cuneatus internal arcuate fibers sensory decussation medial lemniscus bulbothalamic tract external arcuate fibers posterior cuneocerebellar tract anterior bulbocerebellar tract
Prof. Dr. Nikolai Lazarov reticular nuclei: raphe nuclei, pallidus, obscurus & magnus – SERergic (B1-B3)
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Medulla oblongata
glossopharyngeal nerve (IX): inferior salivatory nucleus nucleus ambiguus (IX, X, XI) solitary tract nucleus (VII, IX, X) vagus nerve (X): dorsal motor nucleus of the vagus accessorius nerve (XI) hypoglossal nerve (XII): hypoglossal nucleus trigeminal nerve (V): spinal trigeminal nucleus
22 Prof. Dr. Nikolai Lazarov

descending (corticobulbar) tracts: corticospinal tract pyramidal decussation reticulospinal tract ascending tracts: cuneocerebellar tract anterior and posterior spinocerebellar tracts anterior and lateral spinothalamic tracts spinotectal tract mixed tracts: dorsal longitudinal fasciculus: descending hypothalamic axons ascending visceral sensory axons
Prof. Dr. Nikolai Lazarov 23

synonym: pons Varolii rostral part of hindbrain basal pons: shape – "knob-like“ size: 2 cm long (1543-1575) composition – transverse fibers dorsal pons: covered by cerebellum upper half of fourth ventricle middle cerebellar peduncle functions: relay station from medulla to higher cortical structures assists in the control of movements control of sleep and arousal contains respiratory center and regulates respiration
Prof. Dr. Nikolai Lazarov
Pons
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sulcus basilaris basilar artery median eminence corticospinal fibers, ‘pyramidal tract’ middle cerebellar peduncle trigeminal nerve exit
Pons
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Pons
tectum = superior medullary velum
NB: tectum is Latin for roof,
tegmentum for covering
tegmentum = dorsal part of the pons median sulcus medial eminence sulcus limitans facial colliculus superior fovea locus coeruleus
"the blue spot“ vestibular area auditory tubercle striae medullares
Prof. Dr. Nikolai Lazarov 26

pontine nuclei – ~20 million neurons: excitatory glutamatergic neurons inhibitory GABAergic (5%) neurons noradrenergic nuclei – in upper pontine tegmentum: nucleus coeruleus (A6) parabrachial nuclei, lateral and medial
Pons
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motor nuclei: trigeminal motor nucleus (V) abducens nucleus (VI) facial nucleus (VII) internal loop of facial nerve
Prof. Dr. Nikolai Lazarov 28

trigeminal nuclei (V): main sensory (pontine) nucleus mesencephalic trigeminal nucleus spinal trigeminal nucleus cochlear nuclei (VIII): ventral cochlear nucleus dorsal cochlear nucleus vestibular nuclei (VIII): superior vestibular nucleus (Bechterew) inferior vestibular nucleus (Roller) medial vestibular nucleus (Schwalbe) lateral vestibular nucleus (Deiters) posterior spinocerebellar tract
Prof. Dr. Nikolai Lazarov 29

embryonic origin – rhombencephalon formation – tentorial space between: dorsal pons & upper medulla oblongata cerebellum lateral boundaries: caudal part: gracile&cuneate tubercles fasciculus cuneatus inferior cerebellar peduncle cranial part: superior cerebellar peduncle roof (dorsal wall): cranial portion: superior cerebellar peduncle superior medullary velum caudal portion: } fastigium inferior medullary velum tela choroidea choroid plexuses ventral floor – rhomboid fossa communication openings: median aperture (of Magendie) central lateral apertures (of Luschka) canal cerebral aqueduct (of Sylvius) IIIrd ventricle
Prof. Dr. Nikolai Lazarov
Pons
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Midbrain
location – between forebrain and hindbrain the smallest region of the brainstem – 6-7g the shortest brainstem segment ~ 2 cm long least differentiated brainstem division human midbrain is archipallian – shared general architecture with the most ancient of vertebrates embryonic origin – mesencephalon main functions: a sort of relay station for sound and visual information serves as a nerve pathway of the cerebral hemispheres controls the eye movement involved in control of body movement
31 Prof. Dr. Nikolai Lazarov

Midbrain dorsal part – tectum (quadrigeminal plate): superior colliculi inferior colliculi cerebral aqueduct (of Sylvius) ventral part – cerebral peduncles: dorsal – tegmentum (central part) ventral – cerebral crus substantia nigra
32 Prof. Dr. Nikolai Lazarov

Midbrain
Cerebral peduncle: crus cerebri tegmentum mesencephali substantia nigra two thick semilunar white matter bundles composition – somatotopically arranged motor tracts: corticospinal corticobulbar
} pyramidal tracts – medial ⅔ corticopontine fibers: frontopontine tracts – medially temporopontine tracts – laterally interpeduncular fossa (of Tarin) posterior perforated substance
33 Prof. Dr. Nikolai Lazarov

Midbrain
crus cerebri tegmentum mesencephali substantia nigra location: ventral to the cerebral aqueduct dorsal to the substantia nigra grey matter content: periaqueductal grey matter nuclei of cranial nerves III & IV midbrain reticular formation red nucleus, nucleus ruber:
NB:
tegmentum is Latin for covering parvocellular part – rostral third magnocellular part – caudal portion ventral tegmental area
34 Prof. Dr. Nikolai Lazarov “The Red and the Black” – Stendhal (1830)

Midbrain
superior colliculi (Latin, higher hills) inferior colliculi (lower hills)
Location: rostral half of the tectum, beneath the thalamus brachium of superior colliculus lateral geniculate body alternate grey and white layers superior colliculus nucleus oculomotor nucleus accessory oculomotor nucleus
(of Edinger-Westphal)
Functions: primary integrating center for visual responses visual coordination of eye and head movements – start reflex
Prof. Dr. Nikolai Lazarov corpora quadrigemina = "quadruplet bodies" 35

Cerebellum
Regional location: posterior cranial fossa, covered by cerebellar tentorium beneath the occipital lobes of cerebral hemispheres behind the pons and medulla oblongata roof of the fourth ventricle
Connections with brainstem structures
(three paired fiber bundles – peduncles): midbrain – superior cerebellar peduncle
(brachium conjunctivum) pons – middle cerebellar peduncle
(brachium pontis) medulla – inferior cerebellar peduncle
(restiform body) average weight ~130 g (10% of the total brain volume) cerebellum:cerebrum = 1:8 (adult); 1:20 (infant) more than 50% of all neurons in the brain origin: embryonic hindbrain (rhombencephalon) major integrative center for the coordination of muscular activity
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Cerebellum three sagital subdivisions: median portion, cerebellar vermis two lateral parts, cerebellar hemispheres three transverse subdivisions (lobes): anterior lobe posterior lobe flocculonodular lobe
37 Prof. Dr. Nikolai Lazarov

Cerebellum
Foliar pattern:
folia cerebelli (transverse leaf-like laminae)
Cerebellar fissures:
fissura prima – V-shaped horizontal fissure pre- and postpyramidal fissure ( fissura secunda ) posterolateral fissure
Vermis lobules: superior surface: lingula central lobule monticulus:
• culmen
• declive folium vermis inferior surface: tuber vermis pyramid uvula nodule
38 Prof. Dr. Nikolai Lazarov

Cerebellum
Hemisphere lobules: superior surface:
(vinculum lingulae) alae of the central lobule anterior quadrangular lobule lobulus simplex
(posterior quadrangular lobule) superior semilunar lobule inferior surface: inferior semilunar lobule gracile lobule
(paramedianus) biventral lobule tonsil flocculus
39 Prof. Dr. Nikolai Lazarov

Cerebellum
Archicerebellum: flocculonodular lobe = flocculus + nodulus
(+ part of uvula) functionally related to maintenance of balance: vestibulocerebellum
Paleocerebellum: anterior lobe = lingula, central lobule, culmen,
pyramid, uvula (of vermis) + quadrangular
lobules (of cerebellar hemispheres) regulates body and limb movements, involved in control of muscle tone via the spinal cord: spinocerebellum
Neocerebellum: posterior lobe = the rest of cerebellum most concerned with planning movement and coordination of somatic motor function: cerebrocerebellum (pontocerebellum)
40 Prof. Dr. Nikolai Lazarov

Cerebellum
grey matter: cerebellar cortex, cortex cerebelli intracerebellar (deep) nuclei, nuclei cerebelli white matter, medullary substance
(corpus medullare): primary laminae –
“arbor vitae” (tree of life) intrinsic fibers, fibrae propriae projection fibers myelinated axons of the Purkinje cells afferent fibers –
‘climbing’ and ‘mossy’
41 Prof. Dr. Nikolai Lazarov

Prof. Dr. Nikolai Lazarov
Cerebellum
Molecular layer, stratum moleculare – 300-400 µm: outer stellate neurons and basket cells (GABA)
Fañanás glial cells (astrocytes) – feather-like
Purkinje cell layer, stratum purkinjense:
Purkinje cells
Bergmann glial cells
Granular layer, stratum granulosum
– 100 µm: granule cells – 10 11
(Glu)
Golgi type II cells
(GABA)
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Cerebellum
climbing fibers: originate from the inferior olivary nucleus direct excitatory contacts with Purkinje cells mossy fibers: excitatory synaptic contacts with granule cells rosettes cerebellar glomerulus
43 Prof. Dr. Nikolai Lazarov

Cerebellum
Dentate nucleus, nucleus dentatus
Interpositus nucleus: emboliform nucleus, nucleus emboliformis globose nucleus, nucleus globosus
Fastigial nucleus, nucleus fastigii
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Diencephalon
Prof. Dr. Nikolai Lazarov 45

Thalamus
two egg-shaped lobes of grey matter third ventricle medially hypothalamus hypothalamic sulcus
Gr. θάλαµος = room, chamber nuclear complex – 2% of the total brain of diencephalic mass
~30 mm long
~20 mm wide
~20 mm tall
Prof. Dr. Nikolai Lazarov
Thalamus dorsalis: rostral pole = tuberculum anterius thalami
(“ cushioned seat ”) interthalamic adhesion lamina affixa stria terminalis thalami
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Thalamus
internal medullary lamina
(medial) – Y-shaped: three major nuclear masses: anterior medial lateral nuclear groups external medullary lamina
(lateral): reticular nucleus of the thalamus
Prof. Dr. Nikolai Lazarov 47

Metathalamus
Medial geniculate body: subcortical acoustic center (thalamic relay) inferior colliculi inferior brachium acoustic radiation auditory cortex
Lateral geniculate body: primary processing center for visual information superior colliculi brachium of superior colliculus optic radiation visual (striate) cortex
Prof. Dr. Nikolai Lazarov 48

stria medullaris thalami habenular trigone: habenular nuclei, medial and lateral habenula habenular commissure pineal gland, corpus pineale (epiphysis) posterior commissure subfornical organ (circumventricular organs)
Epithalamus
49 Prof. Dr. Nikolai Lazarov

Subthalamus
subthalamic nucleus (corpus Luysi): basal ganglia contralateral hemiballismus zona incerta nuclei reticulares nuclei campi perizonales
(H
1
- and Н
2
-fields of Forel)
50 Prof. Dr. Nikolai Lazarov

Hypothalamus
Gr.
ὑποθαλαµος = hypo-, cognate to Latin sub- "under" most ventral portion of the diencephalon weight 4-5 g – less than 1% of the total human brain volume preoptic area, area preoptica optic chiasm, chiasma opticum
tuber cinereum, median eminence infundibular tract, infundibulum hypophysis cerebri mammillary bodies, corpora mammillaria
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Hypothalamus
0.5% of the total volume of human brain main function – homeostasis
(maintaining the body's status quo) central control of: visceral functions endocrine effects – release/inhibiting factors neurosecretion: pituitary hormones – oxytocin, vasopressin temperature regulation – dual thermostat instinctive and cyclic behaviors: regulation of food ( appetite ) and water intake control of sexual behavior and reproduction biological clock (sleep-waking cycle) expression of emotion, fear, rage, aversion, pleasure and reward
52 Prof. Dr. Nikolai Lazarov

Diencephalon embryonic origin – prosencephalon location – between the two thalami
(lateral walls) and hypothalamus
53 Prof. Dr. Nikolai Lazarov

anterior boundary – lamina terminalis posterior boundary – posterior commissure pineal recess pineal gland cerebral aqueduct floor – parts of the hypothalamus optic recess infundibular recess roof – layer of ependyma, covered by the tela choroidea ventriculi tertii choroid plexus of the third ventricle communication with: fourth ventricle – cerebral aqueduct (of Sylvius) lateral ventricles – interventricular foramina (of Monro)
Prof. Dr. Nikolai Lazarov
Diencephalon
54

Reticular formation
a reticular formation?
Prof. Dr. Nikolai Lazarov
NB: reticulum means netlike structure build a net.
55

Reticular formation
Median column of reticular nuclei – raphe nuclei (serotonergic):
nucleus raphes obscurus et pallidus in medulla nucleus raphes magnus nucleus raphes centralis superior and in pons nucleus raphes dorsalis in midbrain
Medial column: medullary gigantocellular (magnocellular) nucleus pontine gigantocellular nucleus nucleus tegmenti pontis nucleus pontis caudalis nucleus pontis oralis nucleus cuneiformis nucleus subcuneiformis
Lateral column – parvocellular : nucleus pontis centralis nuclei parabrachiales nucleus tegmentalis pedunculopontinus
56 Prof. Dr. Nikolai Lazarov

Reticular formation
controls ~25 specific behaviors: sleep walking eating urination&defecation sexual activity additional functions: arousal attention cardiac reflexes motor functions regulates awareness relays nerve signals to the cerebral cortex one of the phylogenetically oldest portions of the brain
57 Prof. Dr. Nikolai Lazarov

Telencephalon
weight ~ 1100 g
80% of the total brain mass cerebral hemispheres: pallium superficial grey matter (cerebral cortex) deep grey matter (basal ganglia) white matter ventricular cavity (lateral ventricle) longitudinal fissure of the cerebrum: falx cerebri corpus callosum
58 Prof. Dr. Nikolai Lazarov

Telencephalon
three surfaces: superolateral (convex) medial (flat and vertical) inferior (irregular): six lobes: orbital part frontal lobe parietal lobe tentorial part occipital lobe temporal lobe insular lobe main sulci: central sulcus (of Rolando) limbic lobe lateral sulcus (of Sylvius) parietooccipital sulcus cingulate sulcus collateral sulcus
Prof. Dr. Nikolai Lazarov
NB: sulcus (Latin: "furrow", pl. sulci) 59

Telencephalon surface area : approx. 2200-2850 cm 2 thickness:
1.5 mm – frontal and temporal poles
5 mm – in the precentral gyrus total number of cortical neurons:
2.6-20 billion
0.6x10
9 synapses per mm 3
60000 synapses over one pyramidal neuron one pyramidal nerve cell –
600 neurons
Prof. Dr. Nikolai Lazarov
NB: The human brain contains roughly 90 billion neurons, which transmit information across roughly 150 trillion synapses
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Telencephalon
pyramidal cells – 66% of the total neocortical cell population
(glutamate- and aspartatergic) small-sized (10-15 µm) medium-sized (20-40 µm) large-sized (50-80 µm) giant pyramidal cells of Betz (80-120 µm)
– in the precentral gyrus (motor cortex) stellate (granule) cells – 33% of the total neocortical population (Golgi type II cells) small in size (8-14 µm) – interneurons
(GABA, VIP, SP, CCK, ENK) horizontal cells of Cajal – small and fusiform; in the most superficial cortical layer fusiform cells – “ modified pyramidal cells ” ; spindle-shaped, in the deepest cortical layer cells of Martinotti – small and multipolar; in practically all cortical layers basket cells – horizontally extended neurogliaform stellate cells – small in size pleomorphic cells – modified pyramidal cells;
– large-sized and varying in shape, in the deepest layer
61 Prof. Dr. Nikolai Lazarov

Telencephalon
neocortex (Latin for "new bark" or "new rind") – 6-layered; neopallium ("new mantel") – 90% of hemispheric surface isocortex (Greek isos = "equal rind"); phylogenetically newer part of the cortex allocortex, archipallium – the older, original part of the cerebral cortex;
(Gr. allos = “different, other, another”); fewer than six layers – 3- or 4-layered: paleocortex, paleopallium – 1% of the cerebral cortex
(Gr. palaios = "ancient, old“); 4-layered, olfactory cortex (rhinencephalon) archaeocortex, archipallium – 3-4% of the cortex
(Gr. arche = “beginning”); 3-layered, hippocampal cortex mesocortex – intermediate in form between the allocortex and the isocortex;
5-6-layered, cingulate gyrus
Prof. Dr. Nikolai Lazarov 62

Telencephalon
Cortical layers (Brodmann):
I.
Molecular layer
(plexiform lamina)
II.
External granular lamina
III. External pyramidal lamina
IV. Internal granular lamina
V.
Internal pyramidal
(ganglionic) lamina
VI. Multiform (fusiform) lamina
Meynert – 5 layers (laminae)
B. Lewis – 6 layers
63 Prof. Dr. Nikolai Lazarov

Telencephalon
Prof. Dr. Nikolai Lazarov
Flechsig – 35 myelogenic areas
C. and O. Vogt – 400 areas stria laminae molecularis (plexiformis),
(plexus of Exner) stria laminae granularis externa е
(band of Bechterew) stria laminae granularis interna е
(external band of Baillarger, or band of Gennari) in sulcus calcarinus
(area striata – band of Vicq d’Azyr) stria laminae pyramidalis interna е
(ganglionaris),
(internal band of Baillarger)
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Prof. Dr. Nikolai Lazarov
Telencephalon
Three vast fiber systems: association fibers – fibrae associationes telencephali commissural fibers – fibrae commissurales telencephali projection fibers – fibrae projectiones telencephali
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Telencephalon broad, thick plate of myelinated fibers ~ 10 cm in length rostrum corporis callosi genu corporis callosi truncus corporis callosi splenium corporis callosi
forceps minor (frontal)
forceps major (occipital)
indusium griseum – limbic system stria longitudinalis medialis ( Lancisii ) stria longitudinalis lateralis
66 Prof. Dr. Nikolai Lazarov

Telencephalon internal capsule: anterior limb – 1.5 cm radiatio thalami anterior
tractus frontopontinus (of Arnold) fibrae corticostriatae genu capsulae internae fibrae corticonucleares posterior limb: thalamolentiform part
• fibrae corticospinales
• fibrae corticorubrales
• fibrae corticoreticulares retrolentiform part
• radiatio thalami posterior
• tractus parietooccipitopontinus sublentiform part
• radiatio optica (tract of Gratiolet)
• radiatio acustica
• fibrae corticotectales
• fibrae temporopontinae (tract of Türk)
67 Prof. Dr. Nikolai Lazarov

Telencephalon
Classically: nucleus caudatus nucleus lentiformis claustrum
corpus amygdaloideum – limbic system
The International Basal Ganglia Society: nucleus caudatus nucleus lentiformis nucleus subthalamicus substantia nigra
68 Prof. Dr. Nikolai Lazarov

Telencephalon arcuate mass of grey matter length ~ 7 с m parts: head (caput nuclei caudati) body
(corpus nuclei caudati) tail
(cauda nuclei caudati)
69 Prof. Dr. Nikolai Lazarov

Telencephalon
putamen + nucleus caudatus = striatum (neostriatum)
globus pallidus = pallidum (palleostriatum): globus pallidus lateralis (pallidum externum) globus pallidus medialis (pallidum internum)
70 Prof. Dr. Nikolai Lazarov

Prof. Dr. Nikolai Lazarov
Telencephalon
Left lateral ventricle – first ventricle?
Right lateral ventricle – second ventricle?
NB: Since they are symmetric, a numbering system was not used
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Telencephalon embryonic origin – prosencephalon arched-shaped
– general shape of hemispheres parts: anterior horn (cornu) ~3 cm; triangular shape into the frontal lobe septum pellucidum central part ~4 cm; into the parietal lobe; collateral trigone posterior horn (cornu) – 1.2-2 cm; into the occipital lobe calcar avis inferior horn (cornu) – 3-4 cm; into the temporal lobe hippocampus; collateral eminence composition – cerebrospinal fluid:
plexus choroideus ventriculi lateralis – missed in the anterior and posterior horns communication with: third ventricle – interventricular foramina
(of Monro)
72 Prof. Dr. Nikolai Lazarov

Telencephalon
Papez circuit, 1937: a route the limbic system communicates between the hippocampus, thalamus, hypothalamus, and cortex
Limbic system:
Lat. limbus = "border“, "belt“
Functions – cortical control of: long-term memory learning emotions paleopallium (old mammalian) brain cortical structures – limbic lobe subcortical nuclei: hippocampal formation and fornix amygdaloid nuclear complex septal nuclei hypothalamus, epithalamus various thalamic nuclei part of the basal ganglia
Jamez Papez
(1883-1958)
Prof. Dr. Nikolai Lazarov 73

Telencephalon
Hippocampus, seahorse:
Gr.
ιππος , hippos = horse,
καµπος , kampos = sea monster location – inside the medial temporal lobe three major regions: hippocampus proper
(Ammon’s horn) –
CA1-CA4 fields of Lorente de Nó dentate gyrus three-layered cortices subiculum – transition zone hippocampal functions : behavioral inhibition
(anxiety) learning and recent memory spatial coding
74 Prof. Dr. Nikolai Lazarov

Fornix, Lat. = “vault”, “arch”
C-shaped bundle of fibres (axons) the sole efferent system carries signals from the hippocampus to the mammillary bodies and septal nuclei
Structure: crus of the fornix body of the fornix
(hippocampal) commissure anterior fibers, "precommissural fornix" the septal nuclei and nucleus accumbens posterior fibres, "postcommissural fornix“
(column of the fornix) the mammillary bodies
Prof. Dr. Nikolai Lazarov
Telencephalon
75

Telencephalon
Lat. corpus amygdaloideum
Gr. αµυγδαλή , amygdal ē , “almond”, “tonsil”
Location – deep within the medial temporal lobes
Amygdala nuclei: corticomedial nuclear group – basal ganglia basolateral nuclear group: lateral amygdaloid nucleus basal amygdaloid nucleus accessory basal amygdaloid nucleus central nucleus, medial and lateral
Functions: fear reactivity and other emotional functions feeding sexual behavior
76 Prof. Dr. Nikolai Lazarov

Telencephalon
Michelangelo’s Creation of Adam
(1508-1512)
Meshberger’s interpretation
JAMA 264:1837-1841, 1990
Prof. Dr. Nikolai Lazarov 77

Telencephalon
Functional differentiation of the cerebral cortex
Main cortical areas:
Sensory areas afferent projections
Motor areas efferent projections
Associational (‘silent’) areas
‘Visuopsychic’ cortex
Prof. Dr. Nikolai Lazarov 78

Telencephalon
Cerebral asymmetry (hemispheric dominance)
Left hemisphere: verbal linguistic description mathematical sequential analytical direct link to
‘consciousness’
Right hemisphere: almost non-verbal musical geometrical spatial comprehension temporal synthesis link to ‘consciousness’?
Prof. Dr. Nikolai Lazarov
Roger W. Sperry – ‘’split-brain”
Nobel Prize in Medicine or Physiology 1981
" for his discoveries concerning the functional specialization of the cerebral hemispheres" 79

Prof. Dr. Nikolai Lazarov 80

Prof. Dr. Nikolai Lazarov 81