Cerebral Cortex. Gross Divisions of the Brain. Cerebrum. Diencephalon. Cerebellum. Brainstem. (cerebral hemisphere)

Transcription

1 Cerebral Cortex Gross Divisions of the Brain Cerebrum (cerebral hemisphere) Diencephalon Cerebellum Brainstem 1

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3 Embryonic (developmental) divisions of the Brain Primary vesicle Secondary vesicle Derivatives Prosencephalon telencephalon diencephalon Cerebral cortex Cerebral white matter Basal ganglia Thalamus Hypothalamus Subthalamus Epithalamus Mesencephalon mesencephalon Midbrain Rhombencephalo n metencephalon myelencephalon Cerebellum Pons Medulla oblongata 3

4 Cerebrum Cerebral Hemisphere Telencephalic structure lateral ventricles 1. Cerebral Cortex -lobes, gyrus& sulcus 2. Cerebral White Matter (medullary center) 3. Basal Ganglia Cerebral Cortex Numerical Data Total surface area: : 2200 cm 2 (2.5 ft 2 ) about 1/ surface area about 2/ hidden in the sulci Thickness: : 1.5 mm (V I) mm (M I) Generally, thickest over the crest of the convolution and, thinnest in the depth of sulci Weight: : 600 gm (40 % of total brain weight) 180 gm neurons 420 gm glial cells 4

5 Cerebral Cortex Numerical Data Number of neuronal cells in cerebral cortex neurons billion glial cells billion Estimation of number of cortical neurons von Economo and Koskinas (1925) 14.0 billion Shariff (1953) 6.9 billion Sholl (1956) 5.0 billion Pakkenberg (1966) 2.6 billion Subdivision of Cerebral Cortex Allocortex Archicortex (Archipallium) Palaeocortex (Paleopallium) Isocortex Neocortex (Neopallium) cf. mesocortex, juxtallocortex, mesallocortex 5

6 Isocortex typical 6 layered cortex I. Molecular Layer II. External Granular Layer III. External Pyramidal Layer IV. Internal Granular Layer V. Internal Pyramidal Layer VI. Polymorphic Layer Histological Organization Cellular Elements 1. Pyramidal Cell - output neuron giant pyramidal cell of Betz 2. Fusiform Cell --- modified pyramidal cell 3. Granular (Stellate( Stellate) ) Cell basket cell, double bouquet cell, bipolar cell, chandlier cell, neurogliform cell 4. Horizontal Cell of Cajal (Retzius( Retzius-Cajal cell) 5. Cells of Martinotti Cerebral Cortex 6

7 Cerebral Cortex 1. Pyramidal Cell 2. Fusiform Cell 3. Granular (Stellate( Stellate) ) Cell 4. basket cell 5. double bouquet cell 6. chandlier cell 7. neurogliform cell 8. Horizontal Cell of Cajal 9. Cells of Martinotti a: axon I. Molecular Layer II. External Granular Layer III. External Pyramidal Laye Line of Kaes-Bechterew IV. Internal Granular Layer Outer band of Baillarger - Line of Gennari in area 17 V. Internal Pyramidal Layer Giant pyramidal cell of Bet Inner Band of Baillarger Golgi Nissl Weigert VI. Polymorphic Layer 7

8 Cerebral White Matter Projection fiber Corona radiata Commissural fiber Corpus callosum rostrum, genu, trunk, splenium Anterior commissure Commissure of fornix Association fiber Short association fiber Long association fiber Projection Fibers 8

9 Commissural Fibers 1. Corpus callosum 3. Forceps minor 2. Anterior commissure 4. Forceps major Association Fibers (lateral surface) 1. Superior longitudinal fasciculus 3. Uncinate fasciculus 2. Inferior occipitotemporal fasciculus 4. Perpendicular occipital fasciculus 9

10 Association Fibers (medial surface) 1. Cingulum 4. Superior occipitofrontal fasciculus 2. Uncinate fasciculus 5. Perpendicular occipital fasciculus 3. Inferior longitudinal fasciculus Fibers of Cerebral White Matter (coronal section) 1. Corpus callosum 2. Internal capsule 3. Superior occipitofrontal fasciculus 4. Superior longitudinal fasciculus 5. Inferior occipitofrontal fasciculus 6. Cingulum 7. Uncinate fasciculus 8. Inferior longitudinal fasciculus 10

11 Cortical Afferent Fiber 1. corticocortical fiber association fiber commissural fiber 2. thalamocortical fiber - specific and non-specific 3. extrathalamic subcortical fiber cholinergic fiber - acetylcholine basal nucleus of Meynert mesolimbic dopaminergic fiber - dopamine ventral tegmental area serotonergic fiber serotonine - raphe nuclei norepinephrinergic fiber - norepinephrine nucleus locus ceruleus Cortical Afferent Fiber 1. association fiber 2. commissural fiber 3. specific thalamocortical fiber 4. non-specific thalamocortical fiber 11

12 Cortical Efferent Fiber 1. Corticofugal Fiber - Projection Fiber corticostriate fiber corticothalamic fiber corticorubral fiber corticotectal fiber corticopontine fiber cortico-olivary olivary fiber corticobulbar fiber corticospinal fiber 2. Corticocortical Fiber Association fiber Commissural fiber Cortical Efferent Fiber 5. association fiber 6. commissural fiber 7. corticostriate fiber 8. corticorubral fiber corticopontine fiber corticobulbar fiber 9. corticospinal fiber corticotectal fiber 10. corticothalamic fiber 12

13 Columnar Cortical Unit and Cortical Circuitary A. pyramidal neuron B. excitatory granular cell C. inhibitory granular cell 1. afferent fiber 2. efferent fiber 3. corticothalamic fiber Lobes of the Cerebral Cortex (lateral surface) 1. Frontal lobe 2. Parietal lobe 3. Temporal Lobe 4. Occipital lobe 5. Insula lobe 13

14 Lobes of the Cerebral Cortex (medial surface) 1. Frontal lobe 2. Parietal lobe 3. Temporal Lobe 4. Occipital lobe 5. Insula Lobes of the Cerebral Cortex (basal surface) 1. Frontal lobe 2. Parietal lobe 3. Temporal Lobe 4. Occipital lobe 5. Insula lobe 14

15 Gyri of the Frontal Lobe Lateral Surface Precentral Gyrus --- primary motor area Superior Frontal Gyrus Middle Frontal Gyrus Inferior Frontal Gyrus Pars Opercularis Pars Triangularis ] Broca s area (dominant hemisphere) Pars Orbitalis Medial Surface Medial Frontal Gyrus Paracentral Lobule Basal Surface Rectus Gyrus Orbital Gyrus Inferior Frontal Gyrus Gyri of the Parietal Lobe Lateral Surface Postcentral Gyrus ---- primary somesthetic area Superior Parietal Lobule Inferior Parietal Lobule ---- Wernicke s area Supramarginal Gyrus Angular Gyrus Medial Surface Paracentral Lobule Precuneus 15

16 Gyri of the Occipital Lobe Lateral Surface Lateral Occipital Gyrus Superior Occipital Gyrus Inferior Occipital Gyrus Medial Surface Cuneus Lingual Gyrus Basal Surface Lingual Gyrus Occipitotemporal Gyrus Gyri of the Temporal Lobe Lateral Surface Superior Temporal Gyrus Middle Temporal Gyrus Inferior Temporal Gyrus Basal Surface Lingual Gyrus Occipitotemporal Gyrus Medial Occipitotemporal Gyrus Lateral Occipitotemporal Gyrus 16

17 Gyri of the Cerebral Cortex (Lateral Surface) Gyri of the Cerebral Cortex (Medial Surface) 17

18 Gyri of the Cerebral Cortex (basal surface) Insula of Reil 18

19 Albertus Magnus ( ) 1280) Phrenology of Gall ( ) 1828) and Spurzheim ( ) 1832) Morphological Classification of Cortical Areas based on cytoarchitectonic studies Campbell (1905) about 20 areas Brodmann (1909) areas - most popular Vogt and Vogt (1919) - over 200 areas von Economo (1929) areas 19

20 20

21 Brodmann s cytoarchitectorial map 21

22 PET (positron emission tomography) scan 22

23 Functional Localization of Cerebral Cortex Sensory area primary sensory area secondary sensory area Motor area primary motor area secondary motor area supplementary motor area Association area parietal, occipital and temporal cortex - conceptual elaboration of sensory data prefrontal (frontal) cortex - judgement,, foresight Sensory Areas Somesthetic Area (Somesthesia( Somesthesia) Visual Area (vision) Auditory Area (Hearing) Vestibular Area (Equilibrium) Gustatory Area (Taste) Olfactory Area (Smell) S I, S II V I, V II A I, A II 23

24 Somesthetic Area S I , 1, 2 (postcentral( gyrus) afferernts: ventrobasal complex (VPLc( VPLc,, VPM) discrimination of position and intensity of sensation S II ---- superior bank of lateral fissure no clinical disorders Somesthetic Association Cortex , 7 (parietal lobule, precuneus) afferents: S I, LP of thalamus integration of geneal sensation with past experience tactile agnosia, astereognosis Sensory Homunculus 24

25 Primary Somesthetic Area Thalmocortical connection (VPLc S I) Central region --- cutaneous (3b, 1) Peripheral region --- deep (3a, 2) Secondary Somesthetic Area (SII) superior bank of lateral fissure 25

26 Visual Cortex V I (striate cortex - line of Gennari) greatly thickened outer band of Baillarger heterotypical isocortex afferent: LGd of thalamus visual field defect: homonymous quadranopsia and macular sparing V II , 19 (visual association area) afferents: V I, pulvinar of thalamus integration of vision with past experience visual agnosia cf. occipital eye field Visual Areas 26

27 Visual association areas V4 (color) Face recognition Perceive Facial Expression Auditory Cortex A I , 42 (trannsverse( temporal gyrus of Heschl) heterotypical isocortex afferents: MGv of thalamus - core projection slight diminution in auditory acuity A II (Wernike's( area of original connotaion) not well-defined afferents: non-laminar part (MGm( MGm, MGd) belt projection A I auditory agnosia - sensory aphasia 27

28 Auditory Areas Planum temporale Auditory Areas A I , 42 A II

29 Other Primary Sensory Areas Vestibular Area Area 3a and 2v of S I afferents: VPLo [superior temporal gyrus anterior to A I] Gustatory Area Area 43 (inferior end of postcentral gyrus) afferents: VPMpc Olfactory Area Piriform Lobe - Limbic System Motor Areas primary Motor Area (M I) Premotor Area (PM) Supplementary Motor Area (SMA) Frontal Eye Field 29

30 Motor Homunculus Primary Motor Area M I precentral gyrus of lateral surface anterior part of paracentral lobule heterotypical agranular cortex giant pyramidal cell of Betz afferents: premotor area, SMA, S I VLc, VPLo of thalamus Motor Homunculus Upper Motor Neuron (UMN) syndrome 30

31 Other Motor Areas Premotor Area (PM) lateral surface of 6 afferents: VLc, VPLo of thalamus from cerebellum Supplementary Motor Area (SMA) medial surface of 6 afferents: VLo, Vapc of thalamus from basal ganglia Frontal Eye Field voluntary tracking movement Motor Systems IV Sensory & motor areas: post-central gyrus, parietal lobe pre-central gyrus, frontal lobe corpus striatum (basal ganglia), thalamus 31

32 Motor Systems IV Sensory & motor areas: post-central gyrus, parietal lobe pre-central gyrus, frontal lobe corpus striatum (basal ganglia), thalamus Motor circuits: putamen-globus pallidus-thalamus-premotor cortex caudate-globus pallidus-thalamus-supplementary motor cortex Motor Systems IV Sensory & motor areas: post-central gyrus, parietal lobe pre-central gyrus, frontal lobe corpus striatum (basal ganglia), thalamus Motor circuits: putamen-globus pallidus-thalamus-premotor cortex caudate-globus pallidus-thalamus-supplementary motor cortex Eye-hand co-ordination: frontal eye fields 32

33 Motor Systems IV Sensory & motor areas: post-central gyrus, parietal lobe pre-central gyrus, frontal lobe corpus striatum (basal ganglia), thalamus Motor circuits: putamen-globus pallidus-thalamus-premotor cortex caudate-globus pallidus-thalamus-supplementary motor cortex Eye-hand co-ordination: frontal eye fields Basal ganglia & cerebellum: convergence on descending pathways motor learning Premotor cortex 6 4 Motor cortex Frontal eye field 8 44 Supplementary motor cortex Motor cortex Motor areas of the cortex 33

34 Sensorimotor cortex Putamen Globus pallidus Thalamus Premotor cortex Basal ganglia Sensorimotor cortex Putamen Globus pallidus Thalamus Descending pathways Premotor cortex Basal ganglia 34

35 Sensorimotor cortex Pons Cerebellum Thalamus Cerebellum Cerebellum Thalamus Motor cortex Cerebellum 35

36 Cerebellum Descending pathways Thalamus Motor cortex Cerebellum Sensorimotor cortex Pons Cerebellum Descending pathways Thalamus Motor cortex Cerebellum 36

37 Sensorimotor cortex Sensorimotor cortex Putamen Pons Globus pallidus Cerebellum Thalamus Premotor cortex Descending pathways Thalamus Motor cortex Basal ganglia & cerebellum Basal ganglia via premotor cortex Motor cortex Cerebellum via thalamus Basal ganglia & cerebellum 37

38 Basal ganglia via premotor cortex No plasticity Motor cortex Cerebellum via thalamus Basal ganglia & cerebellum Basal ganglia via premotor cortex Synchronous Motor cortex Cerebellum via thalamus Basal ganglia & cerebellum 38

39 Basal ganglia via premotor cortex Plasticity Motor cortex Cerebellum via thalamus Basal ganglia & cerebellum Sensorimotor cortex Sensorimotor cortex Putamen Pons Globus pallidus Cerebellum Thalamus Premotor cortex Descending pathways Thalamus Motor cortex Basal ganglia & cerebellum 39

40 Association Areas Language Areas , 39, 40, 44, 45 Posterior Parietal Association Area , 7 (39, 40) body image Temporal Association Area , 21, 37, 38 (22) multisensory integration, conceptual ideation Prefrontal Association Area , 10, 11, 12, 46, 47 (44, 45) judgement,, foresight, personality Disorders of Association Cortex Agnosia Tactile agnosia Visual agnosia Alexia Auditory agnosia Apraxia Aphasia Wernicke s (receptive) aphasia Broca s (Motor) aphasia conduction aphasia global aphasia 40

41 Apraxia The inability to execute a voluntary motor movement despite being able to demonstrate normal muscle function. Language Areas Sensory Language Area (Wernike's( area) , 39, 40 Receptive Aphasia - area 22 defect in comprehension, good spontaneous speech Anomic Aphasia - word finding difficulty Jargon aphasia - fluent, but unintelligiable jargon 39 (supramarginal( gyrus), 40 (angular gyrus) Superior Longitudinal Fasciculus Conduction Aphasia good comprehension, good spontaneous speech poor repetition, poor response Motor Language Area (Broca( Broca s area) , 45 Motor Apahsia good comprehension, no speech 41

42 Language Areas (Geschwind( Model) Broca s Area Pars triangularis and pars opercularis of the inferior frontal gyrus of dominant hemisphere. Photograph of the brain of Paul Broca s patient called Tan (real name is Leborgne). 42

43 Paul Broca ( ) 1880) Carl Wernicke ( ) 1905) PET (positron emission tomography) scan 43

44 Prefrontal Association Areas Frontal Granular Cortex Lateral Prefrontal Association Area , 10, 46 judgement,, foresight, problem solving Orbitofrontal Cortex , 12, 47 emotion, olfaction, personality Case of Phineas Gage Prefrontal Leucotomy of Moniz and Freeman Phineas Gage ( , 1861, accident in 1848) 44

45 Phineas Gage s s lesion reconstructed (H. Damasio and R. Frank, 1992) Conceptual Framework of Cerebral Function 45

46 Cerebral Dominance (Lateralization, Asymmetry) Dominant Hemisphere Language speech, writing Calculation Non-dominant Hemisphere Spatial Perception (3D subject) Singing Playing musical instrument Language Speech Writing Calculati on 3D perception Singing Playing Musical instrument 46