Cerebral
Cortex
Won Taek Lee, M.D. Ph.D.
Department of Anatomy,
Yonsei University College of Medicine
❖ The layer of gray matter covering
the entire surface of cerebral hemisphere
neural tube
- 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
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
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
Subdivision of Cerebral Cortex
Allocortex
Archicortex (Archipallium)
Palaeocortex (Paleopallium)
Isocortex
Neocortex (Neopallium)
cf. mesocortex, juxtallocortex, mesallocortex
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) Cell
basket cell, double bouquet cell, bipolar cell,
chandlier cell, neurogliform cell
4. Horizontal Cell of Cajal (Retzius-Cajal cell)
5. Cells of Martinotti
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
Cerebral Cortex
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
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
Cortical Afferent Fiber
1. association fiber
2. commissural fiber
3. specific
thalamocortical fiber
4. non-specific
thalamocortical 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
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
Cortical Efferent Fiber
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
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
Von Economo’s classification of cortical types
1. agranular, 2. frontal, 3. parietal, 4. polar, 5. granular
1. agranular, 2. frontal, 3. parietal, 4. polar, 5. granular
❖ 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
Functional Localization of Cerebral Cortex
Albertus Magnus
(1206-1280)
Phrenology of Gall (1758-1828)
and Spurzheim (1776-1832)
PET (positron emission tomography) scan
❖ 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
Brodmann’s cytoarchitectorial map (Lateral surface)
Brodmann’s cytoarchitectorial map (Lateral surface)
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
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
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
Sensory Homunculus
Thalmocortical
connection
(VPLc → S I)
Central region
--- cutaneous (3b, 1)
Peripheral region
--- deep (3a, 2)
Primary
Somesthetic
Area
Secondary
Somesthetic
Area (SII)
superior bank of
lateral fissure
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
Visual
Areas
V4
(color)
Face
recognition
Perceive
Facial Expression
Visual
association
areas
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
Auditory
Areas
Planum
temporale
Auditory
Areas
A I ----- 41, 42
A II ---- 22
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
primary Motor Area (M I)
Premotor Area (PM)
Supplementary Motor Area (SMA)
Frontal Eye Field
Motor Areas
Motor Homunculus
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
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
Brodman’s Map of Motor and Sensory Areas
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
Order of Cortical Maturation
1
2
3
3
3
2
1
1
❖ 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
Apraxia
The inability to execute a voluntary motor movement despite being able to demonstrate normal muscle function.
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
Language Areas (Geschwind Model)
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.
Paul Broca (1824-1880) Carl Wernicke (1848-1905)
PET (positron emission tomography) scan
Composite radioisotope brain scan
Cerebral Dominance (Lateralization, Asymmetry)
Dominant Hemisphere
Language
– speech, writing
Calculation
Non-dominant Hemisphere
Spatial Perception (3D subject)
Singing
Playing musical instrument
Language
Speech
Writing
Calculation
3D perception
Singing
Playing Musical
instrument
Roger Sperry (1913-1994)
1981 Nobel Laureate
Split Brain
Commissuratomy
(split corpus callosum)
Two minds in one brain?
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
Phineas Gage
(1823-1861, accident in 1848)
Phineas Gage’s lesion reconstructed
(H. Damasio and R. Frank, 1992)
Prefrontal Leucotomy
(Frontal Lobotomy)
Antonio Egas Moniz
Conceptual Framework of Cerebral Function