the cerebral cortex - anatomický ústav 1. lf ukanat.lf1.cuni.cz/souhrny/alekls1002.pdf · cortex...
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THE CEREBRAL CORTEXTHE CEREBRAL CORTEX
Institute of Anatomy, 1st Medical FacultyInstitute of Anatomy, 1st Medical FacultyR. DrugaR. Druga
CORTEX CEREBRICORTEX CEREBRI Definice, Definice, DefinitionDefinition Neocortex, AllocortexNeocortex, Allocortex Vývoj hemisféry a neokortexuVývoj hemisféry a neokortexu Development of the neocortexDevelopment of the neocortex Struktura neokortexuStruktura neokortexu Structure of the neocortexStructure of the neocortex Hlavní typy neuronůHlavní typy neuronů Main types of neuronsMain types of neurons
DP = dorsal pallium
LGE= lateral ganglionic eminence
MGE = medial ganglionic eminence
MGE + LGE
NEOCORTEXNEOCORTEX
Laminar pattern – 6 layersLaminar pattern – 6 layers 10 – 20 billion neurons10 – 20 billion neurons 95 % surface of the hemisphere95 % surface of the hemisphere
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, types of neuronstypes of neurons
Pyramidal Pyramidal neuronsneurons
Apical and basal Apical and basal dendritesdendrites
Dendritic spinesDendritic spines Excitatory (glutamate)Excitatory (glutamate) Homogenous groupHomogenous group 60 – 70 %60 – 70 %
Non-pyramidal Non-pyramidal neuronsneurons
AspinyAspiny Heterogenous groupHeterogenous group Inhibitory (Inhibitory (GABA)GABA) 30 – 40 %30 – 40 %
Pyramidal neurons
Layer V.
M I
Golgi impregnation
Korové interneurony
Projection neurons, excitatatory, glutamate
Long axons
Local circuit neurons, inhibitory, GABA, short 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
Characteristics of layersCharacteristics of layers
I.. Molecular layer – local inhibitory interneuronsI.. Molecular layer – local inhibitory interneurons II. External granular – association neuronsII. External granular – association neurons III. External pyramidal – commissural neuronsIII. External pyramidal – commissural neurons IV. Internal granular – receives thalamocortical IV. Internal granular – receives thalamocortical
projectionsprojections V. Internal pyramidal – projecting neurons (basal V. Internal pyramidal – projecting neurons (basal
ganglia, brain stem, spinal cordganglia, brain stem, spinal cord VI. Multiform layer – corticothalamic neurons VI. Multiform layer – corticothalamic neurons
V – basal ganglia
brain stem
spinal cord
VI - thalamus
Excitatory connections in the neocortexExcitatory connections in the neocortex
Layer 4 – termination of Layer 4 – termination of thalamocortical projectionsthalamocortical projections
Layer 4 – projects to layer 3Layer 4 – projects to layer 3
Layer 3 – projects to layer 5Layer 3 – projects to layer 5
Association areas
Afferent neocortical connectionsAfferent neocortical connections
Thalamic nucleiThalamic nuclei (thalamocortical fibers) (thalamocortical fibers) AmygdalaAmygdala ClaustrumClaustrum HypothalamusHypothalamus
Nc. basalis (Meynert)-cholinergic systemNc. basalis (Meynert)-cholinergic system Raphe nuclei (serotonin)Raphe nuclei (serotonin) Locus coeruleus (noradrenalin)Locus coeruleus (noradrenalin) Subst. Nigra (VTA) - dopaminSubst. Nigra (VTA) - dopamin
Efferent neocortical connections Efferent neocortical connections (excitatory, glutamatergic)(excitatory, glutamatergic)
Thalamic nucleiThalamic nuclei
Basal ganglia (striatum, amygdala, claustrum)Basal ganglia (striatum, amygdala, claustrum)
Brain stem (pretectal area, tectum, nc. ruber, RF, Brain stem (pretectal area, tectum, nc. ruber, RF, nuclei of cranial nerves, pontine ncc., nc. gracilis, nuclei of cranial nerves, pontine ncc., nc. gracilis, nc. cuneatus)nc. cuneatus)
Spinal cord ( corticospinal pathway, interneurons, Spinal cord ( corticospinal pathway, interneurons, motoneurons)motoneurons)
Motor cortical areaMotor cortical area
G. Fritsch and E. Hitzig (1870) G. Fritsch and E. Hitzig (1870) demonstrated that electrical demonstrated that electrical stimulation of the dog´s frontal lobe stimulation of the dog´s frontal lobe results in contralateral muscular results in contralateral muscular contractions (movements)contractions (movements)
Primary motor area, M I
Motor homunculus
Primary motor area M IPrimary motor area M I Precentral gyrus, area 4Precentral gyrus, area 4 Part of the cortex from which movements are easily Part of the cortex from which movements are easily
produced by electrical stimulationproduced by electrical stimulation Motor homunculus (overrepresentation muscles of Motor homunculus (overrepresentation muscles of
the thumb, hand, face, tongue, distorted the thumb, hand, face, tongue, distorted somatotopic representation)somatotopic representation)
Afferents : S I, thalamic VL (cerebellum)Afferents : S I, thalamic VL (cerebellum) Efferents : basal ganglia, thalamus, (VL) RF, Efferents : basal ganglia, thalamus, (VL) RF,
superior colliculus, nc. ruber, RF, pontine ncc., superior colliculus, nc. ruber, RF, pontine ncc., spinal cordspinal cord
Control of distal musclesControl of distal muscles Damage produces paralysis of contralateral muscles Damage produces paralysis of contralateral muscles
(namely upper limb, tongue, facial muscles)(namely upper limb, tongue, facial muscles)
THE CORTICO-SPINAL
PATHWAY
PM
SMA
Premotor area, PMPremotor area, PM
Area 6Area 6 Somatotopic representation of the body Somatotopic representation of the body
musculature, less precisely organizedmusculature, less precisely organized Efferents – M I, basal ganglia, RF, Spinal Efferents – M I, basal ganglia, RF, Spinal
cord (influences paravertebral and proximal cord (influences paravertebral and proximal limb musculature)limb musculature)
Afferents – thalamic VA (basal ganglia), S I,Afferents – thalamic VA (basal ganglia), S I, Preparation to movePreparation to move
Supplementary motor areaSupplementary motor area
Area 6, medial surface of the hemisphereArea 6, medial surface of the hemisphere Somatotopic organization,less precisely Somatotopic organization,less precisely
organizedorganized Afferents – thalamic VA (basal ganglia), Afferents – thalamic VA (basal ganglia),
parietal cortexparietal cortex Efferents – MI, Basal ganglia, RF, Spinal cordEfferents – MI, Basal ganglia, RF, Spinal cord Area is involved in organizing and planning Area is involved in organizing and planning
the sequence of muscle activationthe sequence of muscle activation
Somatosensory area, S I, BA 3, 1, 2
Trigeminal (head) part of S I.
Sensory homunculus
Somatosensory area S ISomatosensory area S I
Postcentral gyrusPostcentral gyrus Areas 3a, 3b, 1, 2Areas 3a, 3b, 1, 2 Afferents : VPL, VPMAfferents : VPL, VPM Efferents : M I, thalamus (VPL, VPM), pontine ncc., Efferents : M I, thalamus (VPL, VPM), pontine ncc.,
nuclei of cranial nerves (V.), spinal cordnuclei of cranial nerves (V.), spinal cord 3a – signals from muscle spindles3a – signals from muscle spindles 3b – cutaneous receptors3b – cutaneous receptors 2 – joint receptors2 – joint receptors 1 – all modalities1 – all modalities
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
Auditory areaAuditory area
Superior temporal gyrus (gyrus temporalis Superior temporal gyrus (gyrus temporalis transversus, Heschl gyrus)transversus, Heschl gyrus)
Area 41 = primary auditory area (A I)Area 41 = primary auditory area (A I) Areas 42, 21, 22 = associated auditory areas (A II)Areas 42, 21, 22 = associated auditory areas (A II) Afferent connections from auditory pathway Afferent connections from auditory pathway
(cochlear ganglion – cochlear nuclei- superior olive (cochlear ganglion – cochlear nuclei- superior olive – inferior colliculus – medial geniculate body – BA – inferior colliculus – medial geniculate body – BA 41)41)
Efferent connections ( A I – A II – temporal, Efferent connections ( A I – A II – temporal, parietal, frontal lobe, Broca area)parietal, frontal lobe, Broca area)
Auditory cortexAuditory cortex
Area 41Area 41 Afferents – auditory pathway (thalamic Afferents – auditory pathway (thalamic
medial geniculate body)medial geniculate body) Efferents – thalamus (medial geniculate Efferents – thalamus (medial geniculate
body), inferior colliculus, associative cortical body), inferior colliculus, associative cortical areas (what and where paths)areas (what and where paths)
Visual cortexVisual cortex
Area 17, granular cortexArea 17, granular cortex Afferents – visual pathway, thalamic lateral Afferents – visual pathway, thalamic lateral
geniculate body. Overrepresentation of geniculate body. Overrepresentation of central part of retina.central part of retina.
Efferents – thalamus (lateral geniculate Efferents – thalamus (lateral geniculate body), area 18, 19, parietal cortex, temporal body), area 18, 19, parietal cortex, temporal cortex.cortex.
Dorsal stream – parietal cortex (where : rods, Dorsal stream – parietal cortex (where : rods, periphery of retina, area 7)periphery of retina, area 7)
Ventral stream – temporal cortex (what- Ventral stream – temporal cortex (what- colors, form, surface : cones, central area of colors, form, surface : cones, central area of retina, area 37, inferior. temporal cortexretina, area 37, inferior. temporal cortex
Receptor mapping
Receptor concentration
fmol/mg protein
(K. Zilles et al. 2010)
Cortical commissural pathwaysCortical commissural pathways
Corpus callosum (250 – 300 millions fibers, Corpus callosum (250 – 300 millions fibers, originate in layer III, mainly excitatoryoriginate in layer III, mainly excitatory
Anterior commissure – pars olfactoria, pars Anterior commissure – pars olfactoria, pars interhemisphericainterhemispherica
Commisura fornicis (hippocampi)Commisura fornicis (hippocampi)
Corpus callosum –
transekce
Comissural
pathways
Associative pathwaysAssociative pathways
Short pathways – interconnect close Short pathways – interconnect close cortical areas ( area 6 with area 4)cortical areas ( area 6 with area 4)
Long pathways – interconnect distal Long pathways – interconnect distal cortical areas or lobes (occipital with cortical areas or lobes (occipital with frontal)frontal)
Cerebral cortexCerebral cortex
All mammals depend on it.All mammals depend on it.
A man without a cortex is almost A man without a cortex is almost vegetable, speechless, sightless, vegetable, speechless, sightless, senseless senseless (D. Hubel and T. Wiesel 1979).(D. Hubel and T. Wiesel 1979).
The cortex supports sensory perception, The cortex supports sensory perception, reasoning, planning and execution of reasoning, planning and execution of behaviors.behaviors.
Thank you !Thank you !
Neocortex - definiceNeocortex - definice
6 vrstev, 6 layers6 vrstev, 6 layers 10 – 20 miliard (bilions) neuronů10 – 20 miliard (bilions) neuronů 95 % povrchu hemisféry95 % povrchu hemisféry 95 % of the hemisphere surface95 % of the hemisphere surface
CALRETININ - IR
PV– ir, V - VI
ÚPRAVA HEMISFÉRYÚPRAVA HEMISFÉRY
Hemisféra – evertovanáHemisféra – evertovanáHemisféra - evaginovanáHemisféra - evaginovaná