THETHE CEREBRALCEREBRAL CORTEXCORTEX

InstituteInstitute ofof Anatomy,Anatomy, 1st1st MedicalMedical FacultyFaculty R.R. DrugaDruga CORTEXCORTEX CEREBRICEREBRI  Definice,Definice, DefinitionDefinition  Neocortex,Neocortex, AllocortexAllocortex  VývojVývoj hemisféryhemisféry aa neokortexuneokortexu  DevelopmentDevelopment ofof thethe neocortexneocortex  StrukturaStruktura neokortexuneokortexu  StructureStructure ofof thethe neocortexneocortex  HlavníHlavní typytypy neuronůneuronů  MainMain typestypes ofof neuronsneurons DP = dorsal pallium

LGE= lateral ganglionic eminence

MGE = medial ganglionic eminence MGE + LGE

NEOCORTEXNEOCORTEX

 LaminarLaminar patternpattern –– 66 layerslayers  1010 –– 2020 billionbillion neuronsneurons  9595 %% surfacesurface ofof thethe hemispherehemisphere LOBES OF THE HERMISPHERE

Nissl staining

Archicortex (Hippocampus, field CA1- 3 layers

Str. or. Str, pyr.

Str. mol. Paleocortex (Olfactory cortex – 3 layers)

I. II, III. Astrocyty (imunoreaction GFAP)

NEOCORTEX,NEOCORTEX, typestypes ofof neuronsneurons

 PyramidalPyramidal  Non-pyramidalNon-pyramidal neuronsneurons neuronsneurons  ApicalApical andand basalbasal  AspinyAspiny dendritesdendrites  HeterogenousHeterogenous groupgroup  Dendritic spines Dendritic spines  InhibitoryInhibitory ((GABA)GABA)  ExcitatoryExcitatory (glutamate)(glutamate)  3030 –– 4040 %%  HomogenousHomogenous groupgroup  6060 –– 7070 %%

Pyramidal neurons Layer V. M I Golgi impregnation Korové interneurony Projection neurons, excitatatory, glutamate Local circuit neurons, inhibitory, GABA, short axons Long axons

PV – ir (GABAergic) CALRETININ – IR (GABAergic) My investigations showed that the functional superiority of the human brain is intimately bound up with the prodigious abundance and unusual wealth of forms of the so-called neurons with the short axons. S. R. y Cajal: Recuerdos de mi vida. 1917.

Interneurons are butterflies of the soul. S.R. y Cajal 1923

Petilla de Aragon (Cajal birthplace) 2005 „Petilla Convention“ K.Brodmann, 1907, 1911

11 regions 52 areas

Layers of the neocortex

Neocortex - vrstvy

CharacteristicsCharacteristics ofof layerslayers

 I.. Molecular layer – local inhibitory interneurons  II. External granular – association neurons  III. External pyramidal – commissural neurons  IV. Internal granular – receives thalamocortical projections  V. Internal pyramidal – projecting neurons (basal ganglia, brain stem, spinal cord  VI. Multiform layer – corticothalamic neurons V – basal ganglia brain stem spinal cord

VI - thalamus ExcitatoryExcitatory connectionsconnections inin thethe neocortexneocortex

 LayerLayer 44 –– terminationtermination ofof thalamocorticalthalamocortical projectionsprojections

 LayerLayer 44 –– projectsprojects toto layerlayer 33

 LayerLayer 33 –– projectsprojects toto layerlayer 55 Association areas AfferentAfferent neocorticalneocortical connectionsconnections

 ThalamicThalamic nucleinuclei (thalamocortical(thalamocortical fibers)fibers)  AmygdalaAmygdala  ClaustrumClaustrum  HypothalamusHypothalamus

 Nc.Nc. basalisbasalis (Meynert)-cholinergic(Meynert)-cholinergic systemsystem  RapheRaphe nucleinuclei (serotonin)(serotonin)  LocusLocus coeruleuscoeruleus (noradrenalin)(noradrenalin)  Subst.Subst. NigraNigra (VTA)(VTA) -- dopamindopamin EfferentEfferent neocorticalneocortical connectionsconnections (excitatory,(excitatory, glutamatergic)glutamatergic)

 ThalamicThalamic nucleinuclei

 BasalBasal gangliaganglia (striatum,(striatum, amygdala,amygdala, claustrum)claustrum)

 BrainBrain stemstem (pretectal(pretectal area,area, tectum,tectum, nc.nc. ruber,ruber, RF,RF, nucleinuclei ofof cranialcranial nerves,nerves, pontinepontine ncc.,ncc., nc.nc. gracilis,gracilis, nc.nc. cuneatus)cuneatus)

 SpinalSpinal cordcord (( corticospinalcorticospinal pathway,pathway, interneurons,interneurons, motoneurons)motoneurons) MotorMotor corticalcortical areaarea

 G.G. FritschFritsch andand E.E. HitzigHitzig (1870)(1870) demonstrateddemonstrated thatthat electricalelectrical stimulationstimulation ofof thethe dog´sdog´s frontalfrontal lobelobe resultsresults inin contralateralcontralateral muscularmuscular contractionscontractions (movements)(movements)

Primary motor area, M I Motor homunculus PrimaryPrimary motormotor areaarea MM II  PrecentralPrecentral gyrus,gyrus, areaarea 44  PartPart ofof thethe cortexcortex fromfrom whichwhich movementsmovements areare easilyeasily producedproduced byby electricalelectrical stimulationstimulation  MotorMotor homunculushomunculus (overrepresentation(overrepresentation musclesmuscles ofof thethe thumb,thumb, hand,hand, face,face, tongue,tongue, distorteddistorted somatotopicsomatotopic representation)representation)  AfferentsAfferents :: SS I,I, thalamicthalamic VLVL (cerebellum)(cerebellum)  EfferentsEfferents :: basalbasal ganglia,ganglia, thalamus,thalamus, (VL)(VL) RF,RF, superiorsuperior colliculus,colliculus, nc.nc. ruber,ruber, RF,RF, pontinepontine ncc.,ncc., spinalspinal cordcord  ControlControl ofof distaldistal musclesmuscles  DamageDamage producesproduces paralysisparalysis ofof contralateralcontralateral musclesmuscles (namely(namely upperupper limb,limb, tongue,tongue, facialfacial muscles)muscles)

THE CORTICO- SPINAL PATHWAY PM SMA PremotorPremotor area,area, PMPM

 AreaArea 66  SomatotopicSomatotopic representationrepresentation ofof thethe bodybody musculature,musculature, lessless preciselyprecisely organizedorganized  EfferentsEfferents –– MM I,I, basalbasal ganglia,ganglia, RF,RF, SpinalSpinal cordcord (influences(influences paravertebralparavertebral andand proximalproximal limblimb musculature)musculature)  AfferentsAfferents –– thalamicthalamic VAVA (basal(basal ganglia),ganglia), SS I,I,  PreparationPreparation toto movemove SupplementarySupplementary motormotor areaarea

 AreaArea 6,6, medialmedial surfacesurface ofof thethe hemispherehemisphere  SomatotopicSomatotopic organization,lessorganization,less preciselyprecisely organizedorganized  AfferentsAfferents –– thalamicthalamic VAVA (basal(basal ganglia),ganglia), parietalparietal cortexcortex  EfferentsEfferents –– MI,MI, BasalBasal ganglia,ganglia, RF,RF, SpinalSpinal cordcord  AreaArea isis involvedinvolved inin organizingorganizing andand planningplanning thethe sequencesequence ofof musclemuscle activationactivation

Somatosensory area, S I, BA 3, 1, 2 Trigeminal (head) part of S I. Sensory homunculus SomatosensorySomatosensory areaarea SS II

 PostcentralPostcentral gyrusgyrus  AreasAreas 3a,3a, 3b,3b, 1,1, 22  AfferentsAfferents :: VPL,VPL, VPMVPM  EfferentsEfferents :: MM I,I, thalamusthalamus (VPL,(VPL, VPM),VPM), pontinepontine ncc.,ncc., nucleinuclei ofof cranialcranial nervesnerves (V.),(V.), spinalspinal cordcord  3a3a –– signalssignals fromfrom musclemuscle spindlesspindles  3b3b –– cutaneouscutaneous receptorsreceptors  22 –– jointjoint receptorsreceptors  11 –– allall modalitiesmodalities Feeling of elictricity Sense of movement Tingling Homunculus Distribution of signals from primary sensory area – to close associative area and finally to distant polysensory areas and to limbic cortex (memory, emotions) LANGUAGE AREAS

Broca : patient losses the ability to speak, produces single words, or syllables. Understanding of language is preserved. Often combined with agraphia (area 44, 45)

Wernicke : sensory or receptive aphasia, spontaneous speech is fluent, but sounds are often put together into meaningless words – „ word salad „. Often combined with alexia – the inability to read (area 39, 40) Auditory area

BA 41 AuditoryAuditory areaarea

 SuperiorSuperior temporaltemporal gyrusgyrus (gyrus(gyrus temporalistemporalis transversus,transversus, HeschlHeschl gyrus)gyrus)  AreaArea 4141 == primaryprimary auditoryauditory areaarea (A(A I)I)  AreasAreas 42,42, 21,21, 2222 == associatedassociated auditoryauditory areasareas (A(A II)II)  AfferentAfferent connectionsconnections fromfrom auditoryauditory pathwaypathway (cochlear(cochlear ganglionganglion –– cochlearcochlear nuclei-nuclei- superiorsuperior oliveolive –– inferiorinferior colliculuscolliculus –– medialmedial geniculategeniculate bodybody –– BABA 41)41)  EfferentEfferent connectionsconnections (( AA II –– AA IIII –– temporal,temporal, parietal,parietal, frontalfrontal lobe,lobe, BrocaBroca area)area)

AuditoryAuditory cortexcortex

 AreaArea 4141  AfferentsAfferents –– auditoryauditory pathwaypathway (thalamic(thalamic medialmedial geniculategeniculate body)body)  EfferentsEfferents –– thalamusthalamus (medial(medial geniculategeniculate body),body), inferiorinferior colliculus,colliculus, associativeassociative corticalcortical areasareas (what(what andand wherewhere paths)paths)

VisualVisual cortexcortex

 AreaArea 17,17, granulargranular cortexcortex  AfferentsAfferents –– visualvisual pathway,pathway, thalamicthalamic laterallateral geniculategeniculate body.body. OverrepresentationOverrepresentation ofof centralcentral partpart ofof retina.retina.  EfferentsEfferents –– thalamusthalamus (lateral(lateral geniculategeniculate body),body), areaarea 18,18, 19,19, parietalparietal cortex,cortex, temporaltemporal cortex.cortex.  DorsalDorsal streamstream –– parietalparietal cortexcortex (where(where :: rods,rods, peripheryperiphery ofof retina,retina, areaarea 7)7)  VentralVentral streamstream –– temporaltemporal cortexcortex (what-(what- colors,colors, form,form, surfacesurface :: cones,cones, centralcentral areaarea ofof retina,retina, areaarea 37,37, inferior.inferior. temporaltemporal cortexcortex Receptor mapping

Receptor concentration fmol/mg protein

(K. Zilles et al. 2010) CorticalCortical commissuralcommissural pathwayspathways

 CorpusCorpus callosumcallosum (250(250 –– 300300 millionsmillions fibers,fibers, originateoriginate inin layerlayer III,III, mainlymainly excitatoryexcitatory  AnteriorAnterior commissurecommissure –– parspars olfactoria,olfactoria, parspars interhemisphericainterhemispherica  CommisuraCommisura fornicisfornicis (hippocampi)(hippocampi) Corpus callosum – transekce

Comissural pathways AssociativeAssociative pathwayspathways

 ShortShort pathwayspathways –– interconnectinterconnect closeclose corticalcortical areasareas (( areaarea 66 withwith areaarea 4)4)

 LongLong pathwayspathways –– interconnectinterconnect distaldistal corticalcortical areasareas oror lobeslobes (occipital(occipital withwith frontal)frontal)

CerebralCerebral cortexcortex  AllAll mammalsmammals dependdepend onon it.it.

 AA manman withoutwithout aa cortexcortex isis almostalmost vegetable,vegetable, speechless,speechless, sightless,sightless, senselesssenseless (D.(D. HubelHubel andand T.T. WieselWiesel 1979).1979).

 TheThe cortexcortex supportssupports sensorysensory perception,perception, reasoning,reasoning, planningplanning andand executionexecution ofof behaviors.behaviors. ThankThank youyou !!

NeocortexNeocortex -- definicedefinice

 66 vrstev,vrstev, 66 layerslayers  1010 –– 2020 miliardmiliard (bilions)(bilions) neuronůneuronů  9595 %% povrchupovrchu hemisféryhemisféry  9595 %% ofof thethe hemispherehemisphere surfacesurface

CALRETININ - IR

PV– ir, V - VI

ÚPRAVAÚPRAVA HEMISFÉRYHEMISFÉRY

HemisféraHemisféra –– evertovanáevertovaná HemisféraHemisféra -- evaginovanáevaginovaná