Cerebral localization part (1)

Cerebral Localization
Hatem Samir M. Shehata, MD, FAAN
Professor of Neurology , Cairo University
SUMMER COURSE - 2018

MAJOR BRAIN REGIONS
Telencephalon Diencephalon Mesencephalon
Myelencephalon
Metencephalon

Cerebral cortex
neocortex allocortex
3 or 4 cell layers6 cell layers, largest part
Paleocortex
olfactory bulb
olfactory tubercle
piriform cortex
Archicortex
hippocampus
dentate gyrus
Periallocortex
anterior insula 
entorhinal cortex
presubicular
retrosplenial
supracallosal
subgenual areas
proisocortex isocortex
cingulate cortex
insula
PHG
homotypic
exception: motor (layer IV)
heterogenetic
it never has 6-layered architecture)
3 4
2–4 mm t 
hick

Cytoarchitecture of the neocortex [6 laminae from outside inwards]:
1. Molecular lamina: dendrites of neurons in other
layers
2. Outer granular lamina*: small pyramidal cells
3. Outer pyramidal lamina*: medium-sized
pyramidal cells
4. Inner granular lamina*: medium-sized granular
cells.
5. Ganglionic [inner pyramidal]: Giant pyramidal
cells of Betz
6. Multiforme lamina: polymorphic small cells of
different types
Lamina IV contains external band of Baillarger which contains terminal
thalamocortical ﬁbers, and line of Gennari which is prominent in calcarine
cortex, the— ‘striate cortex’)

• Cortical laminae comprising in total 28 X 109
neurons and
approximately the 5 times this number of glial cells
• Cortical neurons are arranged in cylindrical mini-columns, each
contains: 100 – 300 vertically interconnected neurons
Columnar Organization of Cerebral Cortex
• There is regional specialization of these
columns; (e.g., in the somato-sensory system,
cells responding to one modality are grouped
together in the columns)
• 30% of pyramidal cells [area 4], 30% [area
6], 40% from parietal (3, 2, and 1)

• The cerebral cortex is divided into two hemispheres linked by
the corpus callosum and the anterior commissure
• In most humans (95% of right-handed and 2/3 of non-right-
handed persons have left hemisphere dominance for language
center)
Right SideLeft Side
Non-verbal
Holistic
Pictorial
Appositional
Parallel – Creative
Verbal
Analytical
Logical
Propositional
Serial – Controlled
Lateralization of brain functions
‫تصويري‬
‫اقتراحي‬

FRONTAL LOBE
the largest of the 4 major
paired lobes of the brain (38%),
2/3 of human brain

functional areas
1. Pre-frontal cortex (4 parts):
1. Dorsolateral prefrontal cortex (DLPFC)
2. Ventromedial (VMPFC)
3. Orbito-frontal cortex (OFC)
4. Anterior cingulate cortex (ACC)
2. Primary motor cortices
3. Pre-motor area
4. Supplementary motor area
5. Frontal eye fields (BA/8)
6. The dominant lobe encompasses  
Broca’s area, and Exner area (speech area)
Frontal lobes lie rostral to the central sulcus and superior to the Sylvian fissure

superior frontal gyrus above the superior frontal sulcus
it is continuous on superomedial margin with the medial frontal gyrus
middle frontal gyrus is between superior and inferior frontal sulci
inferior frontal gyrus is below inferior frontal sulcus and is invaded by
the anterior and ascending rami of the lateral ﬁssure
Lateral surface
Medial surface

medialorb.gyrus
 
lateral 
orb.G
 
anterior 
orb.G
 
post. 
orb. G
gyrusRECTUS
Orbitofrontal area
BA/11
BA/14
BA/13
BA/ 
12/47
medial orbital  
sulcus
lateral orbital sulcus
Most of the OFC is granular, although the caudal parts of area 13 and area 14 are agranular. These caudal regions,
which sometimes includes parts of the insular cortex, responds primarily to unprocessed sensory cues

prefrontal region (anterior to pre-motor area) [9, 10, 11, 12,
32, 33, 46, 47]
✦ Functions:
✦
HIGH-ORDER ASSOCIATION CORTEX:
✦
DLPFC: execution of working memory, problem solving [BA/9,46]
✦
VMPFC: emotional processing
✦
PARALIMBIC:
✦
Orbitofrontal cortex: impulses, drives  
[BA/11,12]
✦
ACC:  
- selective attention (dorsal) [BA/32] 
- anxiety & depression (ventral) [BA/24] 
- autonomic function, it projects to hypothalamus

prefrontal region
1. Mental Changes:
☞ Impaired working memory
☞ Impaired social behavior (adaptability) and personality
changes:
1. Perseveration [difﬁculty in switching between modes of
response]
2. Childish excitement and pathological punning
3. Lack of initiation [aspontaneity] ABULIA, together with
impulsivity and sexual indiscretions
4. Mental incontinence (with lack of concern)
patient becomes aimless and improvident, with loss of tact and self-control, and with
impulsiveness and a failure to appreciate the consequence of reckless behavior
Destruction

Phineas Gage (1823–1860)
• an American railroad construction
foreman, 1848
• accidental explosion, an iron rod  
(1m long, 3.5cm diameter, 6kg) was
ﬂying up through his left cheek 
and out the top of his head
• he lived for a further 12 years
• he became unreliable, with a callous disregard, started visiting
prostitutes (hypesexuality) and drinking heavily, poor social
interaction and temperament changes with remarkably,
preserved intellectual function

2. Headache: common but papilledema is late and may be absent
3. Seizure Phenomena (50%):
4. Tonic perseveration: persistent voluntary contraction [Grasp
Reaction]
5. Paratonia ‘Gegenhalten’: increase in tone in response to
stimulus
6. Anosmia: [orbital surface] “FOSTER KINNEDY”.
7. Ataxia: a false localizing sign [DENTATO-RUBRO-THALAMO-
CORTICAL]
8. Gait apraxia: if bilateral, medial lesions. Catatonia: uncommon
☞ CPS
•
☞ Versive fit
•☞ Forced thinking and loss of contact without warning ☞ Autonomic
prefrontal region
Destruction

catatonia .… paratonia
CATATONIA: INCREASE MUSCLE TONE AT REST ABOLISHED BY VOLUNTARY
ACTIVITIES (DD DRUG-INDUCED EPS)

Lesion:
IRRITATION: motor
Jacksonian fits
DESTRUCTION: flaccid
paralysis
crossed .. inverted; according to motor value
pre-central gyrus
Function:
FACILITATION of Stretch Reflex
EXECUTION. from design to movement …… ’fine, discrete, distal’
primary motor area (BA/4)

pre-motor cortex
(BA-6)
supplementary motor
(BA-4S)anterior to primary motor
area (from sylvan ﬁssure
to 2/3 of way to the
longitudinal ﬁssure)
LOCATION
superior to premotor area
anterior to the leg area of
on the medial surface
above cingulate gyrus
Pre-Supplementary
motor area (Pre-SMA): 
anterior to VAC
Supplementary motor
area proper (SMA):
posterior to VAC
VAC: vertical anterior-commissural line
Ventral (PMv)
Below superior
frontal sulcus
Dorsal(PMd)
Above superior
frontal sulcus

pre-motor cortex (BA-6) supplementary motor
(BA-4S)1. DEVELOP PROGRAMS of
skilled motor activity (pattern and
sequencing of movement)
impulses are direct to area 4; or indirect to
basal ganglia, then thalamus then to area 4
2. inhibition of SR and Grasp
1. mediates internal needs with
external demands in order to
INITIATE motor PROGRAM
2. goal-directed behavior
3. control certain posture and
complex tasks (procedural memory)
Irritation:
-head and eyes deviation to opposite
side
-contralateral complex movement
(windmill movements ‘UL’ and peddling
‘cycling’ LL)
-epileptic seizures: automatisms
Destruction:
1. spasticity, and fanning
2. limb kinetic apraxia, and forced
grasp
Irritation:
-head and eyes deviation to opposite
side
-contralateral tonic raising of arm
with [postural changes]
-simple vocalization or speech arrest
Destruction:
1. slowness of rapid alternating
movements
2. transient paresis
FUNCTIONLESIONS

CINGULATE GYRUS - 1
par-olfactory
area
anterior par-olfactory
sulcus
paraterminal gyrus
anterior commissure
lamina terminalis
isthmus
extends from the subcallosal
gyrus (paraterminal gyrus) in
frontal lobe (anterior) to
isthmus (posterior)
separated from corpus
callosum by callosal sulcus
and bordered superiorly by
cingulate sulcus
anterior portion lies inferior to the medial
frontal gyrus
middle (most horizontal) portion lies inferior
to the paracentral lobule
posterior cingulate gyrus lies inferior to the
precuneus separated from it by the
subparietal sulcus
precuneus

CINGULATE GYRUS - 2
cingulate sulcus
callosal sulcus
cingulate
sulcus
medial
frontal
gyrus
isthmus (posterior)
frontal gyrus
subparietal sulcus
precuneus

CINGULATE GYRUS - 3
cingulate sulcus
callosal sulcus
cingulate
sulcus
medial
frontal
gyrus
isthmus (posterior)
frontal gyrus
subparietal sulcus
marginal portion of
cingulate sulcus
precuneus
cuneus
parieto-
occipital ﬁssure
sub parietal
sulcus
calcarine  
ﬁssure
MCA

Paracentral Lobule
on the medial surface of
cerebral hemisphere
a continuation of the
precentral and postcentral gyri
it includes portions of the
frontal (anterior, SMA) and
parietal lobes (posterior,
somatosensory)
central sulcus is discerned in a
cytoarchetectonic manner on
the medial surface
it controls motor and sensory innervations
of the contralateral LL
it is also responsible for control of
defecation and urination
CINGULATE GYRUS - 4

anterior
cingulate
cortex (ACC)
1.subgenual: BA/25 &
ventral part of 24 and
32
2.perigenual: BA/32
and 24
1.autonomic and endocrine
response to emotion
2.memory, attention
3.pain (connexions with PAG)
anterior
cingulate
cortex (ACC)
mid cingulate
cortex (MCC)
1.anterior: BA/24 and
32
2.posterior: BA/24
3.CMA
1.predictions of behavior
outcome, reward-based
decisions, fear-avoidance
2.helps to execute behavior
mid cingulate
cortex (MCC)
posterior
cingulate
cortex (PCC)
1.ventral: BA/23 and
32
2.dorsal: BA/31
1.topokinetic memory circuit,
2.primary function in
visuospatial orientation
posterior
cingulate (PCC)
retrosplenial
cortex (RSC)
BA/29, 30 spatial navigation,
autobiographical memory
retrieval and imagination
retrosplenial
cortex (RSC)
affective
subdivision
behavioral
subdivision
visuospatial
subdivision
memory
Cingulate Gyrus. Devisions VCL

anterior
cingulate
cortex (ACC)
1.subgenual: BA/25 &
ventral part of 24 and
32
2.perigenual: BA/32
and 24
1.autonomic and endocrine
response to emotion
2.memory, attention
3.pain (connexions with PAG)
anterior
cingulate
cortex (ACC)
mid cingulate
cortex (MCC)
1.anterior: BA/24 and
32
2.posterior: BA/24
1.predictions of behavior
outcome, reward-based
decisions, fear-avoidance
2.helps to execute behavior
mid cingulate
cortex (MCC)
posterior
cingulate
cortex (PCC)
1.ventral: BA/23 and
32
2.dorsal:
1.topokinetic memory circuit,
2.primary function in
visuospatial orientation
posterior
cingulate (PCC)
retrosplenial
cortex (RSC)
BA/29, 30 spatial navigation,
autobiographical memory
retrieval and imagination
retrosplenial
cortex (RSC)
Cingulate Gyrus. Functions
affective
subdivision
behavioral
subdivision
visuospatial
subdivision
memory

White matter fibers
short fibers
(arcuate or
“U"-fibers)
long fibers
(bundles)
EFFERENT AFFERENT
1. optic/acoustic
radiation
2. lemniscii
3. SCP
1. cerebrospinal
tract
2. geniculate
fibers
3. corticopontine
axons connect regions within the
same hemisphere of the brain
association fibers projection fibers
fibers connect cortex with lower
parts of brain and spinal cord
commissural fibers
1. anterior commissure
2. posterior commissure
3. hippocampal
commissure
4. corpus callosum
axons connecting
both hemispheres

Commissural ﬁbers [transverse ﬁbers]
shape: oval in sagittal section with a long
vertical axis that measures about 5 mm
location: in front of the columns of the
fornix
functions:  
1. pain sensation (specifically sharp and
acute pain) 
2. olfaction (it interconnects amygdalas) 
3. memory, emotion, speech and hearing
(interconnects temporal lobes)
Anterior commissure
(precommissure)

> 10 times larger than the anterior commissure
Corpus callosum
Corpus callosum
A.C
rounded band
on dorsal aspect of upper end of
cerebral aqueduct
important in bilateral pupillary light
reﬂex (interconnects the pretectal nuclei)
Posterior commissure (epithalamic)

a C-shaped bundle of ﬁbers connects between
hippocampus and hypothalamus
a part of the limbic system
involved in long-term memory, columns (ant)
1. body (suspended from CC by septum pellucidum)
2. crura
3. alveus (ﬁmbria)
Hippocampal commissure (epithalamic)
Fornices
2nd largest of the commissural connecting
bundles
directly underneath, and adjoins corpus callosum

an irregularly quadrilateral area in
front of the optic tract and behind
the olfactory trigone within the
basal forebrain
Anterior perforated substance
medially: continuous with the
subcallosal gyrus
laterally: lateral stria of the olfactory
tract and continued into the uncus

posterior part of middle gyrus
lesions: – agraphia
Lesions: autonomic signs,
automatisms, olfactory
hallucinations and illusions
Area 45 (Exner’s)
Orbital frontal
middle of inferior gyrus
function: speech production
(dominant) / emotional melodic
component of speech (non-
dominant)
lesion: expressive dysphasia,
dysprosody
Area 44 (Broca’s)
Area 8 [FEF]
posterior part of middle gyrus
Irritation: opposite
Destruction: towards
FRONTAL LOBE LESIONS
Exner’s
Broca
Wernicke’s

FRONTAL LOBE LESIONS
1. Akinetic mutism.
2. Gait apraxia.
3. Incontinence.
4. Perseveration.
5. Lack of judgement and
foresight.
6. Aspontaneity and lability.
1. Contralateral paresis [proximal with
premotor area]
2. Limb kinetic apraxia [premotor area].
3. Forced grasp [SMA]
4. Contralateral oculomotor neglect
[FEF]
5. Perseveration and inflexibility
6. Aspontaneity and lability
7. Olfactory discrimination deficits
8. DOMINANT: non-fluent aphasia
BOTH FRONTAL LOBES EITHER FRONTAL LOBES

TEMPORAL LOBE
% of temporal lobe : total
cortex volume is 22%

TEMPORAL LOBE
lesions of non-dominant lobe are less
clinically obvious [superior quadrantic
ﬁled defect or behavioral changes]
bi-temporal lesions or in dominant
one result in profound impairments
Sylvian Fissure separates temporal lobe from the frontal lobe
(rostrally) and part of parietal lobe (caudally)
temporal lobes have 3 gyri (lat) and (FCH) (med)
deep within temporal lobe is (amygdala)
OTS
lateral
surface
medial
surface
41

merges with circular sulcus to overly insula,
which is exposed by retraction of its lips
it is divided into:
1. stem of lateral sulcus rostrally
2. posterior horizontal ramus (PHR)
3. caudally, splits into 2 terminal
branches: posterior ascending (PA)
and descending limbs (PD)
Sylvian ﬁssure
it has the following branches:
1. in frontal lobe: (a) anterior horizontal limb (AH), (b) anterior ascending
limb (AA) and (c) anterior subcentral sulcus (ASCS) into pre-central gyrus
2. posterior subcentral sulcus (PSCS) into post-central gyrus (parietal lobe)
3. transverse temporal sulcus (TTS) into STG
TEMPORAL LOBE (Cont’d)

posterior to Heschl's gyrus
is “planum temporale”
‘related to the cortical
representation of language’
Heschl's gyri ‘primary auditory cortex’ (BA-41, 42) lies
inside banks of the lateral ﬁssure
pT
transverse plane: it has anterolateral direction
Auditory cortex
ﬁrst cortical structure to process incoming auditory
information
transverse temporal gyri run mediolaterally (towards
the center of brain), rather than front to back as all
other temporal lobe gyri run
coronal plane: has the
form of supratemporal
Ω - shaped protrusion

transverse
temporal
gyrus
long gyri of
insulashort
gyri of
insula
central
sulcus of
insula
al
pl
ps
ms
as pcc
frontal operculum
parietal operculum
temporal operculum
triangular shaped cortex deep within
lateral sulcus and covered by the fronto-
parieto-temporal operculum (~ little lid)
it has a broad base and apex (~ limen
insulae), which is directed downward
and forward towards ‘sylvian ﬁssure’
limen insulae is the lateral most limit of
the anterior perforated substance and
the starting point of the insular cortex
Insular lobe (island of Reil)
limen insulae represents the level at which
MCA bifurcates/trifurcates and at which the
insular cortex is continuous with cortex over
amygdala and STG
involved in consciousness, perception, emotion,
cognition and interpersonal experience

- most of lateral temporal cortex,
(BA-21)
- auditory processing and language
‘dominant’
middle temporal gyrus
inferior temporal gyrus
- most of ventral
temporal cortex, (BA-20)
- visual processing
(ventral visual stream)
VENTROMEDIAL AREA
IFG
lingual g
OTS
collateral s.
parahippo- 
camp g
fusiform
g

collateral s.
fusiform
gparahippo- 
camp g
OTS
OTS separates inferior temporal gyrus from fusiform (lateral occipito-
temporal) gyrus
fusiform gyrus: a long cortical gyrus composed of a temporal or anterior
portion and an occipital or posterior portion
VENTROMEDIAL DIVISION
collateral sulcus separates
‘fusiform gyrus’ from
“parahippocampal and
lingual gyri” (medial
occipito-temporal 
gyrus)
lingual g

(b–b′) is the temporo-occipital line from pre-occipital notch
The collateral sulcus is divided into:
1.rhinal sulcus
2.collateral sulcus proper
3.caudal (occipital) collateral sulcus with its two
terminal branches (medial and lateral)
1. the parahippocampal and lingual gyrus
2. fusiform gyrus into anterior and posterior segments
(a–a′): at the level of the cingulate isthmus divides:
PHG projects anteromedially
to uncus and blends with
cingulate isthmus
VENTROMEDIAL DIVISION

MEDIAL (MESIAL) DIVISION
uncus
mesial temporal region (MTR) has 3 segments
posterior segment
PHG
medial part
(ERC)-BA
28
between collateral S
‘dorsolaterally’ and
hippocampal ﬁssure
‘ventromedially’
anterior segment
lateral part
(PRC)-BA
35/36
rhinal cortexhippocampal 
formation
upper segment

parahippocampal gyrus
PHG
hippocampus
collateral S.PHG
tentorium
ambient  
cistern
PHG continues as the lingual gyrus at the level of the splenium/cingulate isthmus
(retrosplenial cortex)
superior surface faces “pulvinar” across the upper part of ambient cistern
anteriorly PHG has a short recurved part called uncus

rhinal cortex
cortical regions surround the caudal portion of rhinal sulcus
it consists of medial part ‘entorhinal’ (BA/28) and lateral part ’perirhinal’ (BA/35-36)
entorhinal cortex is the main interface between the hippocampus and neocortex  
- plays an important role in declarative (autobiographical/episodic/semantic) memories
Perirhinal (transentorhinal is somewhat synonymous) lies on the medial bank of the
collateral sulcus, lateral to EC. ‘involved in learning and memory, ‘kindling’
phenomenon of epileptogenesis and the spread of limbic seizures’.

relations:
• anterior: rhinal sulcus, separating it from the olfactory cortex
• medially: merges the hippocampus, below pes hippocampi, amygdala, pre and para-
subiculum.
• lateral: collateral sulcus
• posterior: blends with posterior part of PHG till the level of LGB (half way the gyrus)
 
 entorhinal cortex
EC lies in the inferior
surface of uncus without a
clearly demarcated borders

Input from all sensory cortices ﬂows to the perirhinal and
parahippocampal cortices, from where it continues to the
entorhinal cortex, and proceeds to the hippocampus. After
feedback from the hippocampus it then returns the same way
back to the sensory cortices
entorhinal cortex

UNCUS
[Latin for "hook", referencing its shape]
on the tip end of the medial part of PHG
1: Thalamus (cut)
2: Uncus
3, 4: Pulvinar Thalamus
5: Choroidal ﬁssure 
( b e t w e e n f o r n i x a n d
thalamus)
6: Fornix
7: Dentate gyrus
8: Fasciolar gyrus
9: Isthmus
10: Corpus callosum
11: Indusium griseum
12: Cingulate gyrus
13: Lingual gyrus
14: Calcarine sulcus
15: PHG
it houses primary
olfactory cortex,
BA-28 )
it receives ﬁbers
from ‘lateral
olfactory stria’
it belongs to limbic
system
overview

TWO SEGMENTS:
- anterior segment formed of:
‘semilunar G’ and ‘ambient G’
“inferior to semilunar G”
separated by ‘semilunar S’
- posterior segment formed of
superior and inferior parts
separated by uncal sulcus
- anterior and posterior segments
meet at a medially directed apex
1: Uncal G
2: Band of Giacomini
3: Intralimbic G
UNCUS segments

Semilunar gyrus covers the nucleus of the amygdala
Upper part of uncus is formed by the head of
hippocampus, and lower part is formed by the
anterior part of the PHG
intralimbic gyrus forms the posterior end of the
uncus and is the site of attachment of the ﬁmbria
UNCUS

Anterior segment of the uncus
faces the carotid cistern
Posterior segment faces crural
cistern and cerebral peduncle
fimbria above dentate gyrus
choroidal fissure, located
between the thalamus and
fimbria, extends along the
lateral edge of LGB and
pulvinar
Uncal apex is lateral to III CN
PHG faces the midbrain
across the ambient cistern
posterior uncal segment located below uncal notch
is removed to expose head of hippocampus
UNCUS
relationship

Amygdala forms the ROOF
of temporal horn and fills
most of the anterior
segment of the uncus
hippocampus and dentate gyrus are removed,
preserving fimbria and choroid plexus
attached to the choroidal fissure
UNCUS Amygdala
PTO

Uncus (Cont’d)
anterior and posterior parts
meet at a medially directed
apex (4)

Hippocampus
hippocampal formation
encompasses:
• pes hippocampus (a
ridged expanded
anterior end of
hippocampus proper)
• dentate gyrus
• subicular complex

hippocampus a grey matter
bundle, throughout entire
length of ﬂoor of temporal horn
of lateral ventricle
it resembles a ram’s horn
it has been called cornu
ammonis (after the ancient
Egyptian deity, Ammon)
pes hippocampus
Hippocampus

band of  
Giacomini
Gyrus dentatus seen
through the hippocampus
(transparent)
G dentatus
G. 
fasciolaris
dentate G. serrated grey matter ribbon medial to hippocampus,
lateral to PHG
it is covered by ‘ﬁmbria’ that becomes fornix
dentate gyrus
Dentate gyrus
Giacomini

band of Giacomini dentate G. G. fasciolaris indusium griseum
a thin grey matter structure that covers the dorsal surface of
the corpus callosum
dentate gyrus
Dentate gyrus
G. 
fasciolaris
G dentatus
band of  
Giacomini
Gyrus dentatus seen
through the hippocampus
(transparent)

the jam in the roll – from outside to the center: (1) subiculum,
(2) CA ﬁelds (1-4). Finally dentate gyrus forms the
interlocking ‘U’. subﬁelds being affected to different extents
Hippocampus back again

alveus is a thin veil of white
matter covering the
hippocampus
nerve fibers traveling
through alveus from CA
unite on the medial surface
to form ‘fimbria’, which
continues superomedially to
become fimbria of fornix as
the hippocampus terminates
and the fornix begins
ventrally to the splenium of
corpus callosum
FIMBRIA OF HIPPOCAMPUS
Fimbria/Alveus

choroid plexus invaginated into ventricle along
choroid fissure
free thin
border of
‘fimbria’
continues with
epithelium of
choroid fissure
which is above
it
choroidal fissure, located
between the thalamus and
fimbria, extends along the
lateral edge of LGB and
pulvinar
Fimbria/Alveus

blood supply
Posterior cerebral  
artery
Anterior temporal  
branches
Posterior temporal  
branches
Calcarine branch
Parieto-Occipital branch
Temporal Branch of
PCA
Temporal Branch of
PCA
Middle cerebral  
artery
Anterior temporal  
branch
Middle
temporal  
branch
Temporo-
occipirtal branch
temporal branches of the
posterior cerebral artery
supply the inferior surface
of most of the temporal
lobe, but not the temporal
pole

✓ Auditory Cortex
IRRITATION SUPPRESSIO
Nsensory area
(Heschl’s gyrus)
[BA: 41, 42]
- tinnitus - minimal
hearing loss
(bilateralism)psychic area (22):
dominant
- auditory
hallucinations
- vertigo
auditory
agnosia
LESIONS

✓ Non auditory cortex:
1. Epileptic disorder:
According to The ILAE classiﬁcation; two main areas of seizures
origin:
A. The Amygdaloid-Hippocampus (mesial temporal structure):
include autonomic (fear/panic/abdominal), automatism, motionless
stare, olfactory, gustatory (taste), confusion and psychic symptoms
B. Lateral temporal cortex: include auditory, visual spatial illusions/
hallucination, aphasia/speech arrest ‘dominant’ and vertiginous
experiences
dystonic posture of opposite limbs (!!!!!! ?????)

1. Dreamy State and Twilight State: short interruption of conscious
level with staring, and behaving as if in a dream
2. Uncinate Fits:
- Olfactory aura: mesial temporal region Vs. orbital frontal region.
parosmia: usually disagreeable “UNCINATE”. Anosmia: rare
- Gustatory aura: insular and perinsular region, parieto-temporal.
Abnormal disagreeable taste sensation (paraguesia).
- Motor accompaniments:
Oro-alimentary, lip smacking, chewing and swallowing.
Involvement of the amygdala is implied.
Swallowing indicates ictal activity in the frontal lobe structures
(I) Non auditory cortex - epileptic disorders

3. Psychomotor [outdated term] (Complex Partial Seizures): 4 As
AURA: brief subjective symptoms that usually occur at the beginning of a
seizure “warning symptoms”.
May occur in isolation from any other ictal symptom, if so, last longer.
1. Olfactory and gustatory.
2. Abdominal aura: discomfort, nausea, rising epigastric sensation,
stomach pain, flatulence and even vomiting insula
3. Autonomic aura: pallor, flushing, sweating, pupilo-dilatation, alteration in
HR, respiration. Urination and sexual arousal reported occasionally
4. Psychic auras: dysmensic symptoms, dreamy state, and fear in isolation,
or associated with autonomic changes
Non auditory cortex - epileptic disorders (Cont’d)

ABSENCE: arrest reaction or motionless stare.
Not specific for TLE, but it is related to mesial temporal region, if
other data indicate that seizure arouse from the temporal lobe
AUTOMATISM:
Involuntary automatic motor behaviors occurring during absence
or can follow the arrest reaction. The former indicates frontal
onset and the later indicates hippocampal onset
Either perseverative or de novo; simple or complex
AMNESIA: reflects involvement of both hippocampi which results in
inability to form memories of the events happening during the
seizure

4. Secondary Generalization: worse prognosis.
specific features: clonic movements without tonic phase
“propagation from the limbic system avoid brain stem that
produce tonic events”.
dystonic posturing may present: spread to the ipsilateral basal
ganglia
the spread of the seizure into lateral temporal neocortex inactivates
the language centers on the dominant side, postictal aphasia .
5. Temporal Lobe Syncope: collapses (+/-) typical aura of temporal
lobe. Post-ictally patient is confused and amnesic.
6. Ictal vertigo: arise from the lateral temporal and parietal lobes.

dystonic posturing may present: spread to the ipsilateral basal ganglia

Dysmnesia: distorted memory experiences
1. Déjà vu: feeling that one is seeing or experiencing
what one has seen before
2. Déjà entendu: feeling that one is hearing or perceiving
what one has heard before
3. Jamis vu: feeling that something that should be
familiar is strangely unfamiliar
4. Flash backs; forced thinking and rapid recollection of
episodes from the past
(II) Non auditory cortex - perceptual disorders

Visual illusions/hallucinations:
1. Modification of object size (micropsia / macropsia)
2. Modification of object size in a single dimension (stretching)
3. Distortions of an object (warped / curved borders)
(metamorphopsia)
4. FORMED visual hallucinations
5. Telescoping of objects whereby they seem small and far away
6. Pelopsia: objects seem to approach the subject and become
larger.
7. Palinopsia: visual preservation (continuance or recurrence of
many of the same images after the stimulus is gone)
Non auditory cortex - perceptual disorders (Cont’d)

his image serves as an accurate portrayal of the commonly experienced ‘after
images’ or ‘leave a trail'.There is also a signiﬁcant amount of visual drifting
within its background.
moving objects can produce a trail of overlaid, still images behind their path of motion

De-realization and De-personalization
Personality: tamety with hypersexuality, changing in eating behavior,
obsessions, circumstantiality, preoccupation with religion, egocentric,
pseudo-philosophical interests with over-emphasis on trivia
Amnesia:
➡ Left temporal lesion [dominant]: verbal memory deficits  
(more marked if hippocampus is affected)
➡ Right temporal lesion: visual-associate memory  
[spatial locations, faces “prosopagnosia”]
(III) Non auditory cortex - others

Facial weakness
Crossed upper quadrantic ﬁeld defect (50%)
Hippocampus: involved in smell, learning,
retrograde memory, emotions [emotional brain]
Wernickie’s aphasia: posterior part of superior
temporal gyrus and supra-marginal gyrus
(Wernickie area): fluent with impaired
comprehension, repetition, and naming
Non auditory cortex - others (Cont’d)

defined by three anatomical
boundaries:  
(1) central sulcus separates it from
frontal lobe 
(2) parieto-occipital sulcus
separates it from occipital lobes 
(3) lateral sulcus (sylvian fissure)
separates it from the temporal lobe
anterior parietal cortex: posterior to the central sulcus, is the
postcentral gyrus (BA/3,1,2), the primary somatosensory cortical area
posterior part: behind the postcentral sulcus
anatomical devisions
The posterior boundaries with the occipital and temporal lobes are not
clearly defined

posterior parietal cortex is
subdivided into the superior
parietal lobule (BA/5 + 7) and the
inferior parietal lobule (39 + 40),
separated by intraparietal sulcus
posterior part of Sylvian ﬁssure
curves up into (Supra-marginal
gyrus).
STS curves up into (Angular gyrus)
Supra-marginal gyrus, angular
gyrus, and posterior third of STG =
Wernicke area
a rudimentary primary intermediate sulcus of Jensen (PISJ)
separating SMG and AG is identiﬁed in nearly all hemispheresanatomical devisions (Cont’d)
Apper

boundaries:  
(1) anterior: marginal branch
of cingulate sulcus 
(2) posterior: parietooccipital
sulcus 
(3) inferior: subparietal sulcus
precuneus is the portion of
superior parietal lobule on the
medial surface of hemisphere
in front of ‘cuneus’ [occipital
lobe]
Subdivisions:
Sensorimotor (anterior): around margin of marginal
sulcus
Cognitive/Associative (central) Region
Visual (posterior): along the parieto-occipital ﬁssure
  Blue: sensorimotor anterior region and its connections
  Green: cognitive/Associative central Region
  Yellow: visual posterior region
anatomical devisions (Cont’d)

PARIETAL LOBE (CONT’D)
Unilateral lesion [either dominant or non-dominant]:
1.Sensory: Loss of Cortical Sensations:
a. Loss of Epicretic [fine touch: “localization, discrimination,
texture”; stereognosis; fine pressure] more than
Protopathic [pain, and temperature]
b. Loss of temperature more than pain
c. Loss of Joint sense and Position more than vibration
2.Motor: hypotonia, muscle atrophy, and pseudo ataxia
3.Visual field defect: lower quadrantanopia
4.Spasticity of Conjugate Gaze “deviation away from the
lesion”

Non-Dominant [Right] Dominant [Left]
Unilateral Asomatognosia
“anosognosia”: denial of hemiplegic
side / this side of the body is “strange”
Amorphosynthesis: hemi-neglect:
Self: = dressing apraxia, shaving half
beard
Spatial: = constructional apraxia,
“block design, 3D figures”
Bilateral Asomatognosia
[Gerstmann Syndrome, Angular
Gyrus Syndrome]:
1. Finger agnosia.
2. Acalculia.
3. Agraphia.
4. Left / Right disorientation.
Inattention: = hemi-neglect for stimuli:
- Visual inattention: disorientation of
objects in periphery of field
- Perceptual Rivalry
- AlloChiria: stimulated one side,
response in the contralateral side
Bilateral Astereognosis: Tactile
Agnosia
Bilateral Ideational Apraxia
Alexia “central type” with agraphia

Bilateral lesion:
➡ SEVERE CONSTRUCTIONAL APRAXIA
➡ OPTIC ATAXIA
ataxia in which patients have difficulty completing visually guided
reaching tasks in the absence of other sensory cues. Patients with
isolated optic ataxia have intact visual fields, stereoscopic vision,
oculomotor control, proprioception, motor abilities and cerebellar
function, excluding other causes of ataxia with reaching

OCCIPITAL LOBE
the smallest of the 4 major
paired lobes of the brain

it has 3 surfaces: lateral, medial and basal
the most consistent sulcus, the lateral occipital sulcus, divides the lobe into
superior and inferior occipital gyrus
transverse occipital sulcus is continuous with the posterior end of the occipital
ramus of the intraparietal sulcus, and runs across the upper part of the lobe, a short
distance behind the parietooccipital ﬁssure
OCCIPITAL LOBE
the most posterior portion of cerebral
hemispheres
it rests on the tentorium cerebelli
it is separated on medial surface from
parietal lobes by parieto-occipital ﬁssure
more prominent on the medial surface
pre occipital notch
5 cm

VISUAL CORTEX
Primary visual cortex (V1, BA/17): lies on either side
of calcarine fissure [4th layer is divided by band of
heavily myelinated fibers, line of Gennari; which
represents dense axonal input from the thalamus to
layer IV of visual cortex] “striate cortex”
OCCIPITAL LOBE
more prominent on the medial surface
Visual association cortices (peristriate 18, and parastriate 19) surround the primary
visual area
Projection fibers from area 18 and 19 to superior colliculi that influence the
vertical eye movement

OCCIPITAL LOBE (Cont’d)
rods (scotopic) and cones (photopic)
Photoreceptors
First order neuron
bipolar cells of retina
Second order neuron
ganglion cells of retina
Third order neuron
LGB
bipolar
ganglion
VISUAL PATH
optic nerve optic chiasma optic tract
LGBoptic radiationvisual cortex (V1)
LIGHT PATH

from LGB to visual cortex
pass thru retrolentiform
part of internal capsule:
• Ventral ﬁbres ( lower
quadrant of retina) run
into temporal lobe –
Meyers Loop
• Dorsal ﬁbres ( upper
retinal quadrant ) run
into parietal lobe –
Baum’s loop
Optic radiations
Geniculo- calcarine tract

Intellectual, memory, speech, motor, and somatosensory functions are non-
affected.
Lesion in either occipital lobe:
Contralateral homonymous ﬁeld defect: scotoma,
quadrantanopia, hemianopia with or without macular spare
Unilateral optic ataxia (faulty visual reaching): failure of reaching an
object under visual guidance spontaneously or in response to verbal
command. So the patient engages in a tactile search with hands [which are
not coordinated with eyes]
Lesions

Lesions
Lesion in dominant [left] occipital lobe:
Color anomia [defect in naming color of seen objects, patient can
distinguish between colors but cannot identify them by name]
Alexia without agraphia (pure word blindness): if lesion interrupt
splenium of corpus callosum
Object agnosia
anomics have: 
- visual-verbal task defect: errors in matching color
with spoken names 
- pure visual task is intact: ‘matching, sorting colored
discs, perform normally on Ishihara plates 
- pure verbal task is intact: can answer well “what
color is a banana ?“
’intact recognition of color/can sort colors
understand the difference between different colors

Lesions
Lesion in non-dominant [right] occipital lobe:
Color agnosia [inability to name and distinguish colors]
Color achromatopsia: disorder of hue discrimination and ordering
Impaired topographic memory and familiarity
Oculomotor gaze defect
blue banana may seem quite
normal to a color agnosic
Tests for color agnosia: show patients
incorrectly colored objects. A patient
who identiﬁes an inappropriately
colored object as correct as to color,
may have color agnosia
individual is unable to perceive or distinguish
either certain colors or possibly all color; in which,
the world is seen in shades of black and white

Lesion in both occipital lobes:
Bilateral scotoma
Cortical blindness
Visual agnosia
Simultagnosia: inability to perceive all elements holistic (Gestalt)
of a scene simultaneously, while recognition of parts is possible
Anton’s syndrome: denial of being blind
Balint’s syndrome: (1) simultagnosia, (2) optic ataxia, (3)
oculomotor apraxia [inability to look voluntarily to peripheral
ﬁeld, despite that eye movements are full. So, the patient attempts
to turn his head to ﬁxate an object]

Seizure phenomena
Simple visual phenomena (ﬂashing lights, colored balls,
geometric shapes)
Negative phenomena: scotoma, or amaurosis
Perceptual illusions: polyopia, ‘visual perception of multiple
images for a single object'
Sensation of eye movement without ocular deviation
Versive movement of head and eyes
Associated headache in BPECOP

DEFINITION
derived from telencephalon, lateral to diencephalon
separated from it by I.C
a group of segregated nuclei located deep in cerebral hemisphere
a part of extra ∆ motor system involved in the control of posture
and movement primarily by inhibiting motor functions

Archi-Striatum: amygdala (similar embryological
origin but functionally related to limbic system)
Paleo-Striatum (Globus pallidus): medial to
putamen: GPi and GPe
Neo-Striatum [Corpus Striatum] (caudate + putamen)
Caudate: comma shaped formed of: 
1. Head: fused rostrally with putamen 
2. Body: ﬂoor of lateral ventricle, curves
around thalamus 
3. Tail: roof of inferior horn of lateral
ventricle
level of  
anterior commissure
GLOBUS PALLIDUS + PUTAMEN = LENTICULAR NUCLEUS
STN and SN are functionally related to basal
ganglia
]
]

Ventral striatum: ventral extension of
pallidum;  
‘nucleus accumbens’
A part of basal forebrain (substantia innominata)
A connection between the basal ganglia and
limbic system
BASIC ANATOMY (CONT’D)
septal area

Claustrum: medial to insular cortex, separated from putamen  
by external capsule
Substantia Nigra: dorsal to cerebral peduncle  
(dopaminergic):
i) Pars Compacta: cellular, pigmented “melanin”
ii) Pars Reticularis: relatively acellular.
Sub-thalamic Nucleus (STN): bi-convex nucleus 
at mesencephalic-diencephalic junction
E.C
claustrum
external capsule is a white matter contains: 
a. corticocortical fibers: (association areas to another cortical
area) 
b. cholinergic fibers from the basal forebrain to cerebral
cortex 
it eventually joins I.C around the lentiform nucleus
red nucleus

(neostriatum)
lateral
medial
i
e
caudato-lenticular 
gray bridge
caudato-lenticular
gray bridge
Nucleus Accumbens
EC

➡ a complex RE – ENTRANT system
➡ limited down-stream projections to brainstem structures,
but no direct connection with spinal cord
➡ major input gateway to the basal ganglia is striatum
➡ major output is the (GPi/SNr) always INHIBITORY
➡ different functions:
➡ general motor control
➡ eye movements
➡ emotional functions
➡ cognitive functions
BASAL GANGLIA CONNEXIONS

CORTICAL LOOP CORICO – STRIATO – CORTICAL PATHWAY
Cerebral
Cortex
GPi/SNr
ThalamusINPUT
OUTPUT
GABA GABA
SNc
Direct
pathway
Disinhibition
Excitatory
INHIBITION OF THE INHIBITORY = FACILITATORY
Striatum
GLU

GPi/SNr
INPUT
GLU
GABA
STN
Indirect
pathway
GPe
GABA
GLU
Inhibit the inhibition
of stimulant pathway
Inhibitory
hyperdirect pathw
ay
CORTICAL LOOP CORICO – STRIATO – CORTICAL PATHWAY
INHIBITION OF THE INHIBITORY = FACILITATORY
Cerebral
Cortex
Striatum
GABA
Thalamus
OUTPUT

Limbic Cortex
LIMBUS:
Limbus = border
[structures that surround the base of cerebrum]
Deep Structures

1. Pre-frontal and orbito-frontal areas
2. Para-terminal gyrus: anterior to and optic chiasma, receive medial olfactory
stria, and continuous with indosium gresium [a gray mater sheet above corpus
callosum]
3. Cingulate gyrus: above corpus callosum, form a part of circuit of Papez
4. Para-hippocampal gyrus
5. Uncus: medial to PHG
6. Dentate gyrus: posterior to uncus
7. Gyrus Fascularis: posterior continuation of  
parahippocampus and dentate
LIMBIC CORTEX

DEEP STRUCTURES:
Hippocampal Formation: “Sea-Horse”; formed of 3 parts: (Hippocampal
Proper [CA]; Dentate Gyrus; Subicular Region: posterior extension of CA
Amygdala: deep to uncus, continuous with tail of caudate, receive lateral
olfactory stria. 
it gives a mass of nerve fibers called stria terminalis run above thalamus
separate it from caudate , to join with (A) septal nuclei, and (B) hypothalamus.
Amygdalo-septal Circuit

DEEP STRUCTURES:
Septal Nuclei: adjacent to nucleus accumbens.
Medial Forebrain Bundle: connect septal nuclei to hypothalamus to limbic
midbrain
Septal Nuclei

DEEP STRUCTURES:
Basal Forebrain Structures: (substantia innominata): below anterior
commissure, lateral to hypothalamus.
Formed of:
1.Nucleus basalis of Myenert: the origin of cholinergic pathway
2.Nucleus accumbens: ventral extension of GP
Mamillary bodies part of hypothalamus 
located at the ends of the anterior arches of the
fornix to project to the anterior nuclei of the
thalamus via the mammillothalamic fasciculus
Fornix
anterior nuclei of thalamus
Part of hypothalamus, and BG
Limbic midbrain: dorsal longitudinal bundle from
hypothalamus

PAPEZ CIRCUIT
Hippocampus ….. Fornix ….. Mamillary bodies ……
Mamillo-thalamic …… anterior nucleus of thalamus …….
cingulate gyrus ….. Parahippocampus …..
Hippocampus.
It has prolonged after-discharge due to reverberating
circuit: emotions outlast stimuli.
Cortex modiﬁes emotion not switch them on/off

FUNCTIONS OF LIMBIC SYSTEM:
Control of Emotions: fear (amygdala), rage (violent anger): lateral part
of hypothalamus
It has prolonged after-discharge due to reverberating circuit:
emotions outlast stimuli
Motivation: Nucleus accumbens
Control autonomic responses
Olfaction: perception and discrimination of olfaction sensation
Control feeding: amygdala

FUNCTIONS OF LIMBIC SYSTEM:
Hippocampus ….. Fornix ….. Mamillary bodies ……
Mamillo-thalamic …… anterior nucleus of thalamus …….
cingulate gyrus ….. Parahippocampus …..
Hippocampus.
It has prolonged after-discharge due to reverberating
circuit: emotions outlast stimuli.
Cortex modiﬁes emotion not switch them on/off

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