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The Cerebral Cortex 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
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