telencephalon ( “endbrain ”) -...

Telencephalon (Telencephalon ( ““ endbrainendbrain ”” ))

1.1. Telencephalon (cerebrum) Telencephalon (cerebrum) –– general overviewgeneral overview2.2. Cerebral hemispheres:Cerebral hemispheres:

�� surface anatomy surface anatomy –– major sulci, gyri and lobesmajor sulci, gyri and lobes�� cerebral cortex cerebral cortex –– microscopic structure, cytomicroscopic structure, cyto-- and myeloarchitectureand myeloarchitecture�� cerebralcerebral white matter white matter –– association, commissural and projection fibersassociation, commissural and projection fibers

3.3. Basal ganglia Basal ganglia –– structural and functional considerationsstructural and functional considerations4.4. Lateral ventricleLateral ventricle5.5. Olfactory system, rhinencephalonOlfactory system, rhinencephalon6.6. Limbic systemLimbic system7.7. Functional differentiation of the cerebral cortexFunctional differentiation of the cerebral cortex

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 2

Cerebrum Cerebrum –– general overviewgeneral overviewTelencephalonTelencephalon

�� wweighteight ~~ 1100 1100 gg

�� 80% 80% of the total brain massof the total brain mass

�� cerebral hemispheres:cerebral hemispheres:

�� palliumpallium

�superficial grey matter (cerebral cortexcerebral cortex)

�deep grey matter (basal gangliabasal ganglia)

��white matterwhite matter

�ventricular cavity (lateral ventriclelateral ventricle)

�� longitudinal fissure of the cerebrum:longitudinal fissure of the cerebrum:

� falx cerebri

�corpus callosum


� Embryonic origin – rostral part of the prosencephalonprosencephalon

� at birth ~ 340 g = 1/10 of the total body weight� up to 9th postnatal month – weight duplication� mid-3 year ~ 1000 g� about 20 years of age – definitive size and weight

Telencephalon Telencephalon –– development development TelencephalonTelencephalon

� cortex formationcortex formation�� fissuration/sulcationfissuration/sulcation


�� three surfacesthree surfaces ::� superolateral (convex)�medial (flat and vertical)� inferior (irregular):

��orbital partorbital part�� tentorial parttentorial part

�� main sulcimain sulci ::� central sulcus (of Rolando)� lateral sulcus (of Sylvius)�parietooccipital sulcus� cingulate sulcus �

collateral sulcus

�� six lobessix lobes ::�� frontal lobefrontal lobe�� parietal lobeparietal lobe�� occipital lobeoccipital lobe�� temporal lobetemporal lobe�� insular lobeinsular lobe�� limbic lobelimbic lobe

NB:NB: sulcussulcus (Latin: "furrow", pl. (Latin: "furrow", pl. sulcisulci))

Cerebral hemispheresCerebral hemispheresTelencephalonTelencephalon


Superolateral surfaceSuperolateral surfaceTelencephalonTelencephalon


�insular lobe (insula, island of Reil)

Superolateral surfaceSuperolateral surfaceTelencephalonTelencephalon


Medial surfaceMedial surfaceTelencephalonTelencephalon


Inferior surfaceInferior surfaceTelencephalonTelencephalon


�� surfacesurface areaarea:: approx. approx. 22002200--28502850 cmcm22

�� thicknessthickness::� 1.5 mm – frontal and temporal poles� 5 mm – in the precentral gyrus

� total number of cortical neuronsneurons: � 2.6-20 billion

�� 0.6x100.6x1099 synapses per mmsynapses per mm33

�� 6600000 000 synapsessynapses overone pyramidal neuron

� one pyramidal nerve cell –600 600 neuronsneurons

Cerebral cortexCerebral cortexTelencephalonTelencephalon

NB: The human brain contains roughly 90 billion neurons, The human brain contains roughly 90 billion neurons, which transmit information across roughly 150 trillion synapseswhich transmit information across roughly 150 trillion synapses!!


�� pyramidal cellspyramidal 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) cellsstellate (granule) cells – 33% of the total neocortical population (GolgiGolgi type II cellstype II cells)� small in size (8-14 µm) – interneurons

(GABA, VIP, SP, CCK, ENK)�� horizontal cells ofhorizontal cells of CajalCajal – small and fusiform;

in the most superficial cortical layer�� fusiform cellsfusiform cells – “modified pyramidal cells”;

spindle-shaped, in the deepest cortical layer�� cells ofcells of MartinottiMartinotti – small and multipolar;

in practically all cortical layers�� basket cellsbasket cells – horizontally extended�� neurogliaform stellate cellsneurogliaform stellate cells – small in size

�� pleomorphic cells pleomorphic cells – modified pyramidal cells; – large-sized and varying in shape,

in the deepest layer

Cortical cell typesCortical cell typesTelencephalonTelencephalon


�� neocortex neocortex (Latin for "new bark" or "new rind") – 6-layered;

neopalliumneopallium ("new mantel") – 90% of hemispheric surface

isocortexisocortex (Greek isos = "equal rind");

phylogenetically newer part of the cortex

�� allocortex, archipalliumallocortex, archipallium –– the older, original part

of the cerebral cortex;(Gr. allos = “different, other, another”); fewer than six layers – 3- or 4-layered:

�� paleocortex, paleopalliumpaleocortex, paleopallium – 1% of the cerebral cortex (Gr. palaios = "ancient, old“); 4-layered, � olfactory cortex olfactory cortex (rhinencephalon)(rhinencephalon)

�� archaeocortex, archipallium archaeocortex, archipallium –– 3-4% of the cortex (Gr. arche = “beginning”); 3-layered,� hippocampal cortexhippocampal cortex

�� mesocortexmesocortex – intermediate in form between the allocortex and the isocortex;

5-6-layered, � cingulate gyrus

Cytoarchitectonic mappingCytoarchitectonic mappingTelencephalonTelencephalon


Laminar pattern in the cerebral cortexLaminar pattern in the cerebral cortex

I.I. Molecular layer Molecular layer (plexiform lamina)(plexiform lamina)

II.II. External granular External granular laminalamina

III.III. External pyramidal External pyramidal laminalamina

IV.IV. Internal granular Internal granular laminalamina

V.V. Internal pyramidal Internal pyramidal (ganglionic) lamina(ganglionic) lamina

VI.VI. Multiform (fusiform) Multiform (fusiform) laminalamina

� MeynertMeynert – 5 layers (laminae)� B. LewisB. Lewis – 6 layers

TelencephalonTelencephalon

Cortical layers Cortical layers (Brodmann):(Brodmann):


�� heterotypicheterotypicalal cortexcortex (Brodmann):� agranular type – III, V, VI (motor cortexmotor cortex)� granular type (koniocortex) – II, IV layers

(sensory cortexsensory cortex)

�� hhomomotypicotypicalal cortexcortex:� frontal type cortex – premotor cortexpremotor cortex� parietal type – postcentral cortexpostcentral cortex� polar type – visuopsychic cortexvisuopsychic cortex

Variants of neocortical structureVariants of neocortical structure

5 major types of cerebral cortex:5 major types of cerebral cortex:



�� FlechsigFlechsig – 35 myelogenic areas

�� C. and O. C. and O. VogtVogt – 400 areas

�� stria laminae molecularisstria laminae molecularis (plexiformis),

(plexus of Exner)

�� stria laminae granularis externastria laminae granularis externaее

(band of Bechterew)

�� stria laminae granularis internastria laminae granularis internaее

(external band of Baillarger, or

band of Gennari)

� in sulcus calcarinus

(area striataarea striata – band of Vicq d’Azyr)

�� stria laminae pyramidalis internastria laminae pyramidalis internaее

(ganglionaris),

(internal band of Baillarger)

Myeloarchitecture: cortical fiber structureMyeloarchitecture: cortical fiber structureTelencephalonTelencephalon


� Three vast fiber systemsfiber systems:

�� association fibersassociation fibers –

fibrae associationes

telencephali

�� commissural fiberscommissural fibers –

fibrae commissurales

telencephali

�� projection fibersprojection fibers –

fibrae projectiones

telencephali


Cerebrum Cerebrum –– white matterwhite matter



Association fibersAssociation fibers� shortshort association fibers:

� fibrae arcuatae cerebri (U fibers)

� longlong association fibers:

� cingulum

� superior longitudinal fasciculus

� inferior longitudinal fasciculus

� uncinate fasciculus �

inferior frontooccipital fasciculus

� arcuate fasciculus

� vertical occipital fasciculus


� anterior (rostral) commissure� commissure of the fornix

(hippocampal commissure)� commissura magna

(corpus callosum)


Commissural fibersCommissural fibers


� 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


Corpus callosumCorpus callosum


�� internal capsule: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)


Projection fibersProjection fibers


�� ClassicallyClassically:� nucleus caudatus� nucleus lentiformis� claustrum� corpus amygdaloideum – limbic system

�� The International Basal Ganglia SocietyThe International Basal Ganglia Society:� nucleus caudatus

� nucleus lentiformis

� nucleus subthalamicus

� substantia nigra


Basal nuclei (Basal nuclei ( ““ Basal gangliaBasal ganglia ”” ))


� Lat. claudereclaudere – barrier�� a thin ((1-2 mm) lamina of grey matter� capsula externa� capsula extrema� part of the lentiform nucleus?� part of the insular cortex?� polysensory integrator


ClaustrumClaustrum


� arcuate mass of grey matter� length ~ 7 сm� parts:

� head head ((caput nuclei caudati)� body body

(corpus nuclei caudati)

� tail tail

((caudanuclei caudati)


Caudate nucleusCaudate nucleus


� putamen + nucleus caudatus = striatumstriatum (neostriatum)(neostriatum)� globus pallidus = pallidumpallidum (palleostriatum)(palleostriatum)::

� globus pallidus lateralis (pallidum externum)� globus pallidus medialis (pallidum internum)


Lentiform nucleusLentiform nucleus


�� functionsfunctions::� role in the planning and

modulation of movements� involved in a variety of cognitive processes

involving executive function

�� pathologypathology::�dyskinesia (tremor, athetosis, chorea, ballismus)

�muscle rigidity�paralysis agitans (Parkinson’s disease)�Huntington’s chorea

� striatum + pallidum


Striopallidal systemStriopallidal system


Lateral ventricleLateral ventricle

�� Left lateral ventricleLeft lateral ventricle –– first ventricle?first ventricle?

�� Right lateral ventricle Right lateral ventricle –– second ventricle?second ventricle?


NB:NB:NB:NB:NB:NB:NB:NB: Since they are symmetric, a numbering system was not used

for the lateral ventricles!



Lateral ventricleLateral ventricle�� embryonic origin embryonic origin –– prosencephalon�� archedarched--shapedshaped – general shape of hemispheres

�� partsparts::�� anterior hornanterior horn (cornu) (cornu) ~3 cm; triangular shape

into the frontal lobe � septum pellucidum�� central partcentral part ~4 cm; into the parietal lobe;

collateral trigone�� posterior hornposterior horn (cornu) (cornu) – 1.2-2 cm;

into the occipital lobe � calcar avis�� inferior horninferior horn (cornu) (cornu) –– 3-4 cm;

into the temporal lobe � hippocampus; collateral eminence

�� composition composition – cerebrospinal fluid::�� plexus choroideus ventriculi lateralis plexus choroideus ventriculi lateralis –

missed in the anterior and posterior horns

�� communication withcommunication with::�� third ventricle third ventricle –– interventricular foramina interventricular foramina

(of(of MonroMonro))


�� rhinencephalon includesrhinencephalon includes:� olfactory bulb and tract� olfactory striae and trigone� olfactory tubercle� primary olfactory cortex:

�� piriform areapiriform area (gyrus ambiens)�� periamygdaloid areaperiamygdaloid area

(gyrus semilunaris)� secondary olfactory cortex:

�� entorhinal areaentorhinal area, cranial part of parahippocampal gyrus


Olfactory system, rhinencephalonOlfactory system, rhinencephalon

�� Gr.Gr. rhinencephalonrhinencephalon = nose= nose--brain brain rhinrhin == nosenose, encephalon = , encephalon = brainbrain

� part of the basal forebrain� mediates olfaction (the sense of smell),

olfactory brainolfactory brain


� Functions – cortical control of:� long-term memory� learning� emotions

�� Papez circuit, 1937Papez circuit, 1937:� a route the limbic system

communicates between the hippocampus, thalamus, hypothalamus, and cortex


Limbic systemLimbic system

Jamez PapezJamez Papez(1883(1883--1958)1958)�� Limbic system: Limbic system:

Lat. Lat. llimbusimbus = = "border"border““,, "belt"belt““

�� paleopallium (old mammalian) brainpaleopallium (old mammalian) brain� cortical structures – limbic lobelimbic lobe� subcortical nuclei:

�� hhippocampippocampal formation and fornixal formation and fornix�� amygdaloid nuclear complexamygdaloid nuclear complex�� septal nucleiseptal nuclei�� hypothalamus, epithalamushypothalamus, epithalamus�� various thalamic nucleivarious thalamic nuclei�� part of the basal gangliapart of the basal ganglia



Hippocampal formationHippocampal formation

�� Hippocampus, seahorse: Hippocampus, seahorse: Gr.Gr.ιπποςιππος, , hipposhippos = horse, = horse, καµποςκαµπος, , kamposkampos = sea monster= sea monster

� location – insidethe medial temporal lobe

�� three major regionsthree major regions:�� hippocampus proper hippocampus proper

(Ammon(Ammon’’s horn) s horn) ––CA1CA1--CA4 fields CA4 fields of of Lorente de NLorente de Nóó

�� dentate gyrusdentate gyrus�� threethree--layered corticeslayered cortices

�� subiculum subiculum –– transition zonetransition zone

�� hippocampal functions:hippocampal functions:�� behavioral inhibitionbehavioral inhibition

(anxiety)�� learning and learning and

recent memoryrecent memory�� spatial codingspatial coding



FornixFornix

�� Fornix, Lat. = Fornix, Lat. = ““vaultvault””, , ““archarch””

� 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



Amygdala (amygdaloid nuclear complex)Amygdala (amygdaloid nuclear complex)

�� Lat. Lat. corpus amygdaloideumcorpus amygdaloideumGr. Gr. αµυγδαλήαµυγδαλή, , amygdalamygdalēē, , ““almondalmond””, , ““tonsiltonsil””

� Location – deep within the medial temporal lobes

� Amygdala nuclei:�� corticcorticomedial omedial nuclear group nuclear group – basal ganglia�� basolateral basolateral nuclear groupnuclear group:

�� lateral amygdaloid nucleuslateral amygdaloid nucleus�� basal amygdaloid nucleusbasal amygdaloid nucleus�� accessory basal amygdaloid nucleusaccessory basal amygdaloid nucleus

�� central nucleus, central nucleus, medial and lateralmedial and lateral

� Functions:� fear reactivity and other

emotional functions� feeding� sexual behavior


MichelangeloMichelangelo’’s s Creation of AdamCreation of Adam(1508-1512)


Localization of cerebral functionsLocalization of cerebral functions

MeshbergerMeshberger’’s interpretation s interpretation JAMA 264:1837JAMA 264:1837--1841, 19901841, 1990


Schädellehre, Phrenology, 1796 Gr. φρήν, phrēn, "mind"; λόγος, logos, "knowledge“

von Economovon Economo(1925) – 109 areas

BrodmannBrodmann (1909) – 52 cytoarchitectural areas


Cytoarchitectural mapsCytoarchitectural maps

Franz Joseph Franz Joseph Gall Gall

(1758(1758--1828)1828)

CampbellCampbell (1905) – 20 areas


�� Main cortical areas:Main cortical areas:�� Sensory areasSensory areas �� afferent projections

�� Motor areasMotor areas �� efferent projections

�� AssociationalAssociational (‘silent’) areas

�� ‘‘VisuopsychicVisuopsychic’’ cortexcortex


Functional differentiation of the cerebral cortexFunctional differentiation of the cerebral cortex


�� Right hemisphereRight hemisphere ::� almost non-verbal� musical� geometrical� spatial comprehension� temporal synthesis� link to ‘consciousness’?

�� Left hemisphereLeft hemisphere :� verbal� linguistic description� mathematical� sequential� analytical � direct link to

‘consciousness’

TelencephalonTelencephalonCerebral asymmetry (hemispheric dominance)Cerebral asymmetry (hemispheric dominance)

Nobel Prize in Medicine or Physiology 1981 "for his discoveries concerning the functional specialization of the cerebral hemispheres"

Roger W. Sperry Roger W. Sperry –– ‘’‘’splitsplit--brainbrain””

Prof. Dr. Nikolai LazarovProf. Dr. Nikolai Lazarov 36Проф. д-р Николай Лазаров


An old brain with new tricksAn old brain with new tricksTelencephalonTelencephalon

Dean Frank: New Information about Albert Einstein’s brainFront. Evol. Neurosci. 1:3, 2009


�� primary somatomotor areaprimary somatomotor area (M(M--I)I) = primary (precentral) motor cortex(areaarea 44 of of BrodmannBrodmann):

� gyrus precentralis

� lobulus paracentralis

�� second somatomotor areasecond somatomotor area = premotor cortex(areaarea 66 and parts of areas 8, 44, 45):

� most caudal parts of gyri frontales sup., med. et inf.

�� paresis and palsyparesis and palsy

�� apraxiaapraxia

�� supplementary motor area (Msupplementary motor area (M--II)II):

� medial surface – medial part of medial part of aarea 6rea 6� between area 4 and cingulate gyrus

� ahead of lobulus paracentralis

�� ““motor homunculusmotor homunculus”” (Latin: (Latin: ““little manlittle man””))ofof Penfield andPenfield and RasmussenRasmussen


Somatomotor areasSomatomotor areas


�� frontal eye fieldfrontal eye field – middle frontal gyrus“center for voluntary eye movements”:� considerable (inferior) part of area 8area 8� area 6 behind and probably area 9 in front

�� second frontal eye field second frontal eye field –– anterior to the aboveanterior to the above�� motor speech areamotor speech area::

� posterior part of the inferior frontal gyrus –areaarea 4444 and part of area 45 (gyrus Brocaegyrus Brocae)

�� motormotor aphasiaaphasia(paralysis of speech in man)(paralysis of speech in man)�� agramatismusagramatismus

Paul Broca, Paul Broca, 1861 speech center


Somatomotor areasSomatomotor areas


� I.P. Pavlov – Pavlov's cortical irradiation hypothesis,"cortical representations" of sensory modalities � primary (first-order) areas� associative (second- and third-order) areas –

involved in integration of incoming sensory information

�� primary somatosensory area (Sprimary somatosensory area (S--I) I) ––areas 3, 1 and 2areas 3, 1 and 2:� gyrus postcentralis� part of lobulus paracentralis

�� secondary somatosensory area (Ssecondary somatosensory area (S--II) II) –– area 5area 5� lobulus parietalis superior

�� third somatosensory area third somatosensory area (S(S--III) III) –– area 7area 7

� between the primary and parainsular cortex

�� tactile agnosiatactile agnosia�� astereognosis astereognosis

((inability to identify an object by touch without visual inputinability to identify an object by touch without visual input ))

ИИ..ПП. . ПавловПавлов


Somatosensory areasSomatosensory areas

�� ““sensorysensory homunculushomunculus””ofof Penfield andPenfield and RasmussenRasmussen


�� primary visual cortex (Vprimary visual cortex (V--I)I) – area 17area 17calcarine sulcus �� optic radiation�granular type cortex (koniocortex)

�� area striataarea striata (striate cortex)(striate cortex)�3% of cerebral surface area�10% of cortical neurons – numerous GABAergic interneurons

�� visual agnosiavisual agnosia –– inability of the inability of the brain brain to make senseto make sense((““mentallymentally blindnessblindness””))

�� secondary visual cortex secondary visual cortex (association areas):(association areas):� in the occipital lobe

��VV--II II –– area 18area 18

��VV--III III –– area 19area 19


Visual receptive areasVisual receptive areas


�� primary auditory cortexprimary auditory cortex (A-I) = area area 4411 � acoustic radiation� granular type cortex� upper part of gyrus temporalis superior� gyri temporales transversi (Heschl’s gyrus)

�� secondary auditory cortexsecondary auditory cortex (A-II) = areaarea 4242; belt areas – association (second-order) auditory area:� gyrus temporalis superior

�� acoustic agnosia acoustic agnosia (word (word but not soundbut not sound deafness)deafness)

�� tertiary auditory cortextertiary auditory cortex (A-III) = areaarea 2211; association (third-order) auditory area:� between the first, second acoustic

area and parainsular cortex


Auditory receptive areasAuditory receptive areas


�� supramarginal gyrussupramarginal gyrus ((areaarea 40)40) – inferior parietal lobe:� involved in phonological and

articulatory processing of words � agraphia (writing apraxia = inability to write)� astereognosia� apraxia (inability to execute a normal volitional act)

�� angular gyrusangular gyrus ((areaarea 39):39):� written word is translated to

internal monologue� alexia (“word blindness”) – inability

to recognize written words or the meaning of words

�� sensory aphasiasensory aphasia

C. WernickeC. Wernicke1874

�� speech area of speech area of WernickeWernicke ((areaarea 2222))

processes dominant word meanings(semantic processing):� posterior section of the

superior temporal gyrus� gyrus supramarginalis� gyrus angularis


Gnostic areasGnostic areas


� gyrus postcentralis� sucus intraparietalis

� the lowest part of gyrus postcentralis, parietal operculum (areaarea 4343)� parainsular cortex?

�� Gustatory area:Gustatory area:

�� sensations of turning movements and dizzinesssensations of turning movements and dizziness

�� loss of gustatory sensationsloss of gustatory sensations�� gustatorygustatory hallucinationhallucinationss


Other cortical areasOther cortical areas�� Vestibular area:Vestibular area:


�� olfactoryolfactory hallucinationhallucinationss

� primary olfactory cortex:�� prepiriform cortex prepiriform cortex –– lateral olfactory gyrus lateral olfactory gyrus �� gyrus ambiensgyrus ambiens

�� periamygdaloid area periamygdaloid area –– lateral olfactory strialateral olfactory stria �� gyrus semilunarisgyrus semilunaris

� secondary olfactory cortex:�� entorhinal areaentorhinal area, cranial part of parahippocampal gyrus

Olfactory cortex (piriform lobe)Olfactory cortex (piriform lobe)


�� rostral part ofrostral part of frontal lobe(areasareas 99--1212):�ability to perform a task

�� intellectual preservationintellectual preservation

�� successful abolition successful abolition of obsessional statesof obsessional states

�� pain reliefpain relief

�� removal of anxiety removal of anxiety and fearand fear

�� in bilateral ablation in bilateral ablation ((sectioningsectioning))

and frontal lobotomy and frontal lobotomy ((leucotomyleucotomy))::


Prefrontal cortexPrefrontal cortex


TemporoTemporo --polar (polar ( ““ psychicpsychic ”” ) cortex) cortex� Temporal pole – a paralimbic regionparalimbic region:

� part of an extended limbic system� role in both social and emotional processes,

including face recognition� integration of emotion with perception� recognition from auditory or visual cues �

visual and acoustic hallucinations


Homer J. SimpsonHomer J. Simpson


AgeAge --related functional specializationrelated functional specialization


Sex differences in the cerebrumSex differences in the cerebrum


Thank youThank you……

telencephalon ( “endbrain ”) -...

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