1. Cerebral
Cortex

2. Cerebral Cortex  The layer of gray matter covering
the entire surface of cerebral hemisphere
Migration of neurons from inner mantle layer of
neural tube
Accommodates enormous number of neurons
- Large surface area accommodates
more neurons than deep nuclei
- Gyri and sulci also increase surface area
- Laminar organization also accommodates
enormous number of neurons

3. Numerical Data Cerebral Cortex
 Total surface area: 2200 cm2 (2.5 ft2)
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. Numerical Data Cerebral Cortex
 Number of neuronal cells in cerebral cortex
neurons billion
glial cells billion
 Estimation of number of cortical neurons
von Economo and Koskinas (1925) billion
Shariff (1953) billion
Sholl (1956) billion
Pakkenberg (1966) billion

5. Subdivision of Cerebral Cortex
Allocortex
Archicortex (Archipallium)
Palaeocortex (Paleopallium)
Isocortex
Neocortex (Neopallium)
cf. mesocortex, juxtallocortex, mesallocortex

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

7. Histological Organization
Cerebral Cortex
Histological Organization
Cellular Elements
1. Pyramidal Cell - output neuron
giant pyramidal cell of Betz
2. Fusiform Cell --- modified pyramidal cell
3. Granular (Stellate) Cell
basket cell, double bouquet cell, bipolar cell,
chandlier cell, neurogliform cell
4. Horizontal Cell of Cajal (Retzius-Cajal cell)
5. Cells of Martinotti

8. Cerebral Cortex 1. Pyramidal Cell 2. Fusiform Cell
3. Granular (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

9. II. External Granular Layer III. External Pyramidal Layer
I. Molecular Layer
II. External Granular Layer
III. External Pyramidal Layer
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 Betz
Inner Band of Baillarger
VI. Polymorphic Layer
Golgi Nissl Weigert

10. 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

11. Cortical Afferent Fiber
1. association fiber
2. commissural fiber
3. specific
thalamocortical fiber
4. non-specific

12. Cortical Efferent Fiber
1. Corticofugal Fiber - Projection Fiber
corticostriate fiber
corticothalamic fiber
corticorubral fiber
corticotectal fiber
corticopontine fiber
cortico-olivary fiber
corticobulbar fiber
corticospinal fiber
2. Corticocortical Fiber
Association fiber
Commissural fiber

13. 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

14. Columnar Cortical Unit and Cortical Circuitary
A. pyramidal neuron
B. excitatory
granular cell
C. inhibitory
1. afferent fiber
2. efferent fiber
3. corticothalamic fiber

15. Regional Variation of Cortical Lamination
A. Homotypical isocortex
association cortex
B. Heterotypical isocortex
1. granular cortex
--- primary sensory cortex
V I (17), S I (3), A I (41)
2. agranular cortex
--- motor cortex
M I (4), PM (6)

16. Functional Localization of Cerebral Cortex
 Phrenology of Gall and Spurzheim
 Clinical evidences
Broca’s area (1861)
Jacksonian epilepsy (1864)
 Experimental evidences
Fritsch and Hitzig (1870) --- motor cortex
von Gudden (1870) visual cortex
Ferrier (1873) ---- auditory cortex

17. PET (positron emission tomography) scan

18. 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. Brodmann’s cytoarchitectorial map (Lateral surface)

20. Brodmann’s cytoarchitectorial map (Lateral surface)

21. 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

22. Sensory Areas Somesthetic Area (Somesthesia) S I, S II
Visual Area (vision) V I, V II
Auditory Area (Hearing) A I, A II
Vestibular Area (Equilibrium)
Gustatory Area (Taste)
Olfactory Area (Smell)

23. Somesthetic Area S I ----- 3, 1, 2 (postcentral gyrus)
afferernts: ventrobasal complex (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

24. Sensory Homunculus

25. Secondary Somesthetic Area (SII)
superior bank of
lateral fissure

26. Visual Cortex V I ----- 17 (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

27. Visual
Areas

28. Visual association areas
(color)
Face
recognition
Perceive
Facial Expression

29. 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, MGd) – belt projection
A I
auditory agnosia - sensory aphasia

30. 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

32. Motor Areas primary Motor Area (M I) Premotor Area (PM)
Supplementary Motor Area (SMA)
Frontal Eye Field

33. Motor Homunculus

34. Primary Motor Area M I ------- 4 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

35. 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

36. Brodman’s Map of Motor and Sensory Areas

37. Association Areas Language Areas ----- 22, 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

38. Order of Cortical Maturation1 3 3 2 1 2 1 3
Order of Cortical Maturation

39. 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. Apraxia
The inability to execute a voluntary motor movement despite being able to demonstrate normal muscle function.

41. Language Areas Sensory Language Area (Wernike's area) ---- 22, 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’s area) , 45
Motor Apahsia
good comprehension, no speech

42. Language Areas (Geschwind Model)

43. Paul Broca (1824-1880) Carl Wernicke (1848-1905)

44. PET (positron emission tomography) scan

45. Composite radioisotope brain scan

46. Cerebral Dominance (Lateralization, Asymmetry)
Dominant Hemisphere
Language
– speech, writing
Calculation
Non-dominant Hemisphere
Spatial Perception (3D subject)
Singing
Playing musical instrument

47. Language
Speech
Writing
Calculation
3D perception
Singing
Playing Musical
instrument

48. (split corpus callosum)
Split Brain
Commissuratomy
(split corpus callosum)
Two minds in one brain?
                                           
Roger Sperry ( )
1981 Nobel Laureate

49. 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

50. Phineas Gage
( , accident in 1848)

51. Phineas Gage’s lesion reconstructed
(H. Damasio and R. Frank, 1992)

52. Prefrontal Leucotomy (Frontal Lobotomy)
Antonio Egas Moniz

53. Conceptual Framework of Cerebral Function