2. 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
Cerebral Cortex
3. Numerical Data
Total surface area: 2200 cm2 (2.5 ft2)
about 1/3 ------ surface area
about 2/3 ------ hidden in the sulci
Thickness: 1.5 mm (V I) - 4.5 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
Cerebral Cortex
4. Numerical Data
Number of neuronal cells in cerebral cortex
neurons ----------- 10-15 billion
glial cells ---------- 50 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
Cerebral Cortex
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
9. 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. 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
11. Cortical Afferent Fiber
1. association fiber
2. commissural fiber
3. specific
thalamocortical fiber
4. non-specific
thalamocortical fiber
14. A. pyramidal neuron
B. excitatory
granular cell
C. inhibitory
granular cell
1. afferent fiber
2. efferent fiber
3. corticothalamic fiber
Columnar Cortical Unit and Cortical Circuitary
15. 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)
Regional Variation of Cortical Lamination
21. based on cytoarchitectonic studies
Campbell (1905) -------- about 20 areas
Brodmann (1909) ------ 47 areas
- most popular
Vogt and Vogt (1919) - over 200 areas
von Economo (1929) -- 109 areas
Morphological Classification of Cortical Areas
24. 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
Functional Localization of Cerebral Cortex
25. 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)
Sensory Areas
26. 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
------- 5, 7 (parietal lobule, precuneus)
afferents: S I, LP of thalamus
integration of geneal sensation with past experience
tactile agnosia, astereognosis
Somesthetic Area
30. 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 ---- 18, 19 (visual association area)
afferents: V I, pulvinar of thalamus
integration of vision with past experience
visual agnosia
cf. occipital eye field
Visual Cortex
33. A I ----- 41, 42 (trannsverse temporal gyrus of Heschl)
heterotypical isocortex
afferents: MGv of thalamus - core projection
slight diminution in auditory acuity
A II ---- 22 (Wernike's area of original connotaion)
not well-defined
afferents: non-laminar part (MGm, MGd) – belt projection
A I
auditory agnosia - sensory aphasia
Auditory Cortex
36. 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
Other Primary Sensory Areas
37.
38. primary Motor Area (M I)
Premotor Area (PM)
Supplementary Motor Area (SMA)
Frontal Eye Field
Motor Areas
40. 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
Primary Motor Area
41. 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 ---------- 8
voluntary tracking movement
Other Motor Areas
43. Language Areas ----- 22, 39, 40, 44, 45
Posterior Parietal Association Area
------ 5, 7 (39, 40)
body image
Temporal Association Area
------ 20, 21, 37, 38 (22)
multisensory integration, conceptual ideation
Prefrontal Association Area
----- 9, 10, 11, 12, 46, 47 (44, 45)
judgement, foresight, personality
Association Areas
45. Agnosia
Tactile agnosia
Visual agnosia
Alexia
Auditory agnosia
Apraxia
Aphasia
Wernicke’s (receptive) aphasia
Broca’s (Motor) aphasia
conduction aphasia
global aphasia
Disorders of Association Cortex
46. Apraxia
The inability to execute a voluntary motor movement despite
being able to demonstrate normal muscle function.
47. 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) --- 44, 45
Motor Apahsia
good comprehension, no speech
Language Areas
49. Photograph of the brain
of Paul Broca’s patient
called “Tan” (real name
is Leborgne).
Broca’s Area
Pars triangularis and
pars opercularis of the
inferior frontal gyrus of
dominant hemisphere.
56. Frontal Granular Cortex
Lateral Prefrontal Association Area
------ 9, 10, 46
judgement, foresight, problem solving
Orbitofrontal Cortex
------ 11, 12, 47
emotion, olfaction, personality
Case of Phineas Gage
Prefrontal Leucotomy of Moniz and Freeman
Prefrontal Association Areas
