Functional areas of brain.2015.dk

FUNCTIONAL AREAS OF BRAIN
DR.DEEPAK N.KHEDEKAR
LTMMC &GH
SION-
MUMBAI-22
JAN-2016
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Dr.Deepak N.Khedekar.LTMMC & GH,SION
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Important Sulci and Gyri on superolateral
surface
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Important Sulci and Gyri on medial
surface
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3

Introduction
• Cerebral cortex has been divided into 52
functional area by Brodmann (1909)
• Typical cortical areas…
1.Motor areas
2.Sensory areas
3.Association areas
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Korbinian Brodmann
• ( 1868 – 1918) German
Neurologist
• became famous for his
definition of the cerebral
cortex into 52 distinct
regions from their
histological characteristics,
known as Brodmanns
functional areas of
cerebral cortex
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Brodmanns functional areas on supero-lateral surface
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Brodmanns functional areas medial surface Brain
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Functional areas in Frontal lobe
1. Primary motor area
2. Premotor area
3. Supplementary motor area (MsII)
4. Frontal eye field -Area 8
5. Motor speech area of Broca- Area 44 & 45
6. 6.Prefrontal cortex- Area 9, 10, 11and 12.
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1.Primary motor area
1.Location:
• Precentral gyrus (area 4)
• Extends to the paracentral
lobule
2.Affrerents :
• Premotor area (Area 6)
• Somesthetic or
somatosensory cortex
• Thalamic nucleus(VPL),
(which receives info. from
cerebellum)
Basal ganglia1/5/2016 10
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Primary motor area-Area 4
3.Efferents :
Fibres from area 4 and
area 6 forming…
1.corticospinal
2.corticonuclear and
3.corticobulbar tracts.
• Representation of body in
is inverted (Inverted
homonculus )
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Primary motor area- Inverted Homonculus
• Specific regions within the
motor area are responsible
for movements in the
specific parts of the body.
•
• Only movements are
represented in area (not
muscles)
• Human body is
represented in an upside
down manner in the
precentral gyrus
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Inverted Homonculus
• Pharyngeal region and
tongue are represented
in the lowermost part.
• followed by face, hand,
trunk and thigh.
• legs, feet and perineum
are represented on the
medial surface of the
hemisphere in the
paracentral lobule.
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4.Clinical Correlation
• Area of motor cortex
controlling a particular
movement …
Proportional to the skill
involved in that movement
,not the bulk of muscle
• Face especially the lips,
tongue, larynx and hand
have disproportionately
larger areas
• Trunk and lower limb have
smaller areas.
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5.Associated motor functions of Primary motor
cortex
• Contralateral finger, hand, and wrist movements
(Dorsal)
• Contralateral lip, tongue, face, and mouth movement
(Lateral)-Swallowing / laryngial movement
• Contralateral lower limb (knee, ankle, foot, toe)
movement (Mesial)
• Motor imagery
• Learning motor sequences
• Volitional breathing control
• Control of rhythmic motor tasks (i.e. bicycling)
• Inhibition of blinking / voluntary blinking-Horizontal
saccadic eye movements
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Primary motor cortex-Associated motor
functions
Motor imagery:
• can be defined as a dynamic state during which
an individual mentally simulates a given action.
• This phenomenal experience implies that the
subject feels herself/himself performing the
action.
• Corresponds to the so-called internal imagery (or
first person perspective) of sport psychologists.
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Primary motor cortex
Somatosensory functions :
• Kinesthetic perception of limb
movements
• Vibro-tactile frequency
discrimination
• Finger proprioception
• Thermal hyperalgesia
(contralateral)
• Response to touch/observed
touch (Left)
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Primary motor cortex
Other functions:
• Verbal
• Topographic memory
(motor memory) for visual
landmarks
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• Primary motor area controls
the opposite half of the
body
• Significant bilateral control
on muscles of face, tongue,
mandible,larynx,pharynx
and axial musculature
• Lesion-
• causes voluntary muscle
paralysis of the contra-
lateral side.
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2.Premotor area-Area 6
• 1.Location:
• Anterior to primary motor
area in the posterior part of
the superior, middle,inferior
frontal gyri.
• Lacks giant pyramidal cells
• Direct contribution to the
pyramidal and other
descending motor
pathways
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Premotor area-Area 6
2.Efferents:
• Main site of cortical
origin of extra-pyramidal
system.i.e.
Cortico-rubral (Red
nucleus)
Cortico-nigral (substantia
nigra)
Cortico-olivary (olivary
nucleus complex)
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Premotor area-Area 6
3.Associated functions
• Successful performance of the voluntary
motor activities.
• Stores the programmes of motor activity
assembled as a result of past experience.
• Responsible for programming the intended
movements of the primary motor area
• Controlling the movements in progress.
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4.Clinical correlation
• Lesions of premotor (secondary motor) area
produce difficulty in the performance of
skilled movements.
• Apraxia, loss of the ability to do simple or
routine acts in the absence of paralysis.
• Agraphia-when writing is also involved.
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Primary somatomotor area
(MsI)
=
Primary motor area
Premotor area
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3.Supplementary motor area (MsII)
1.Location:
• Medial frontal gyrus anterior to the paracentral lobule
• Body is represented from before backwards in
craniocaudal order.
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Supplementary motor area (MsII)
2.Associated functions::
• Stimulation of MsII produces complex
movements.
3.Clinical Correlation:
• Described as ‘Assumption of posture’ with
bilateral effects, including turning the head,
assuming positions of trunk and lower limb, etc.
• Lesions of area produce bilateral flexor
hypotonia with no paresis or paralysis
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4.Frontal eye field -Area 8
1.Location:
• Posterior part of the middle frontal
gyrus just anterior to the facial area of
the precentral gyrus.
2.Associated functions:
• Stimulation of this region causes
deviation of both the eyes especially to
the opposite side (conjugate
movements of the eyes).
• Controls voluntary scanning
movements of the eyes and is
independent of the visual stimuli.
• Connected to the visual area of occipital
cortex by association fibres.
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5.Motor speech area of Broca -Areas 44 and 45
1.Location:
• Pars triangularis (area 45) &
pars opercularis (area 44) of
inferior frontal gyrus of frontal
lobe of left hemisphere
(dominant hemisphere) in most
of right handed the individuals.
• 30% cases it is present in the
right hemisphere and persons
are left handed.
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Motor speech area of Broca- Area 44 & 45
• Responsible for the production of
expressive speech/vocalization
• Brings about the formation of
words by its connections with the
adjacent primary motor area.
• Thus there is appropriate
stimulation of the muscles of the
larynx, mouth, tongue, soft palate,
and the respiratory muscles.
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• Lesions result in loss of ability
to produce speech, i.e.
expressive aphasia (motor
aphasia).
• Patients retain the ability to
think about the words, they
can write the words and they
can understand their meaning
when they see or hear them.
• Language is understood but it
cannot be expressed in
speech even though there is
no paralysis of muscles of lips,
tongue, and vocal cords, etc.
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6.Prefrontal cortex- Area 9, 10, 11and 12.
• 1.Location:Envelop the
frontal pole.
• 2.Associated functions:
• Concerned with the
individual's personality.
• Well developed in
primates especially in
humans.
• Exerts its influence in
determining the initiative
and judgement of an
individual.1/5/2016 31
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Prefrontal cortex- Area 9, 10, 11and 12.
3.Clinical correlation:
• Concerned with depth of
emotions, social, moral and
ethical awareness,
concentration, orientation
and foresightedness.
• Capable of associating
experiences that are
necessary for the production
of abstract ideas.
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Functional areas in the parietal lobe
1. Primary sensory area-Areas 3, 1 and 2
2. Secondary sensory area (SmII)
3. Sensory association area- Areas 5 & 7
4. Sensory speech area of Wernicke -Area 39 &
40
5. Primary auditory area (Brodmann's areas 41
and 42)
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1.Primary sensory area - 3, 1 and 2
1.Location-Postcentral
gyrus
• Extends into the posterior
part of the paracentral
lobule on the medial
surface of the hemisphere.
• Opposite half of the body is
represented up-side down
exactly in same fashion as
in the primary motor
(Inverted homonculus)
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Primary sensory area-Area 3,1 & 2
2.Afferents:
• Receives projection fibres from ventral
posterolateral (VPL) and ventral
posteromedial (VPM) nuclei of the
thalamus.
• Area is concerned with the perception
of…
 Extero-ceptive (pain, touch and
temperature)
 Proprioceptive (vibration, muscle,and
joint sense) sensations from the
opposite half of the body.
• Sensations from pharynx, larynx and
perineum go to both sides.
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Primary sensory area - 3, 1 and 2
2.Associated functions
• Lesions of primary sensory
area lead to…
 loss of appreciation of
exteroceptive and
proprioceptive sensations
from the opposite half of
the body.
 Crude pain, temperature
and touch sensations often
return, but this is believed
to be due to functions of
the thalamus
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Primary sensory area - 3, 1 and 2
• Area of cortex assigned for
a particular part is
proportional its functional
significance (i.e. to the
intricacies of sensations
received from it).
• Thumb, fingers, lips and
tongue have a
disproportionately large
representation.
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Associated functions- Primary somatosensory
area
• Localization of touch
• Localization of temperature
• Localization of vibration
• Localization of pain
• Finger proprioception
• Deep proprioception
• Voluntary hand movement
• Volitional swallowing
• Tongue movement and perception
• Skillful coordinated orofacial movement(i.e. whistling)
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2.Secondary sensory area (SmII)
1.Location:
• In the upper lip of the
posterior ramus of the
lateral sulcus.
• Face area lies most anterior
and the leg area is
posterior.
• Whole body is represented
bilaterally.
• Area relates more to the
pain perception.
• Ablation of this area may
relieve intractable pain.
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3.Sensory association area- Areas 5 & 7
1.Location:
• superior parietal lobule.
perception of shape, size,
roughness, and texture of
the objects.
•Stereognosis-
•Ability of the individual to
recognize the objects
placed in his/her hand
without seeing
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• Ideomotor apraxia –
• Lesions in the left superior
parietal lobe are associated with
loss of the ability to produce
purposeful, skilled movements as
the result of brain pathology not
caused by weakness, paralysis,
lack of coordination, or sensory
loss.
• Tactile agnosia or astereognosis.
Inability to recognize or identify
an object by its feel.
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4.Sensory speech area of Wernicke (Area 39 & 40 )
1.Location:
• Sensory speech area is
located in the left
dominant hemisphere
occupying…
 1.Posterior part of the
superior temporal gyrus of
temporal lobe and angular
gyrus (area 39)
 2.Supramarginal (area 40)
gyri of the inferior parietal
lobule.
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Sensory speech area of Wernicke (Area 39 & 40 )
interpretation of language
through visual and auditory
input.
• An essential zone for
constant availability of the
learned word patterns.
• Angular and supramarginal
gyri are essential for the
process of learning such as
reading, writing, and
computing.
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Arcuate fasciculus
The sensory and motor speech areas exist together in
one hemisphere only.
The Wernicke's area is connected to the Broca's area
by a bundle of nerve fibres called arcuate fasciculus.
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• Receptive sensory aphasia -Lesions of Wernicke's
area in the dominant hemisphere produce loss of
ability to understand the spoken and written
speech.
• Since Broca's area is unaffected, the expressive
speech is unimpaired and the individual can
produce a fluent speech.
• Pt is unaware of the meaning of the words he
uses consequently he uses, incorrect words or
even non-existent words.
• (incomprehensive foreign language).
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Aphasic disorders
• Lesions of these areas produce wide variety of
aphasic disorders, like
disabilities in reading (alexia),
writing (agraphia),
computing (acalculia)
recognition of names of the objects (anomia).
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Global aphasia
• Lesions involving both
Broca's and Wernicke's
speech areas result in loss
of the production of
speech as well as loss of
understanding of the
spoken and written
speech.
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Comparison between motor and
sensory aphasias
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5.Primary auditory area
(Brodmann's areas 41 and 42)
Located : -
• Inferior wall of the lateral sulcus, and to be
very specific on the superior surface of the
superior temporal gyrus occupying the
anterior transverse temporal gyrus
(Heschl's gyrus)
• Extends slightly to the adjacent part of the
superior temporal gyrus
Afferents :
• Medial geniculate body through auditory
radiations.
• Medial geniculate body receives input
from organ of Corti in the cochlea of inner
ear of both the sides but mainly from the
opposite side.
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Primary auditory area
(Brodmann's areas 41 and 42)
3.Associated function:
• Concerned with the reception of isolated
impressions of loudness, quality and pitch
of the sound.
• Picks up the source of the sound.
 Unilateral lesions:
• result in slight loss of hearing because it
receives auditory input from the cochleae
of both sides, but
• Loss will be greater in the opposite ear.
 Bilateral lesions: Complete cortical
deafness
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6.Secondary auditory area/auditory association area
(Brodmann's Area 22)
1.Location:
On the lateral surface of
the superior temporal
gyrus slightly posterior to
the primary auditory
area which it surrounds
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Secondary auditory area/auditory association area
(Area 22)
• Receives auditory impulses from primary
auditory area and correlates them with the
past auditory experiences.
• Area is necessary for the interpretation of
the sound heard.
• Auditory verbal agnosia:.
• Lesions result in an inability to interpret the
meaning of the sounds heard, and the
patient may experience word deafness
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Functional areas in the occipital lobe
1.Primary visual area/striate area
(Brodmann's area 17)
2.Secondary visual area/visual association area
(Brodmann's area 18 V2 and 19 V3,V4,V5)
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1.Primary visual area(17,V1)
1.Location :
 Walls and floor of the posterior part of
the calcarine sulcus ( postcalcarine
sulcus)
 Extend around the occipital pole on to
the superolateral surface of the
hemisphere.
• Most marked structural feature of the
visual cortex is the presence of white
stria (visual stria of Gennari), hence
the name, the striate area.
• Visual cortex is relatively thin and
contains huge amount of granule cells.
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Visual pathway
2.Afferents:
• Lateral geniculate body via geniculocalcarine tract/optic
radiations.
• From temporal half of the ipsilateral retina and the nasal
half of the contralateral retina.
• Right half of the field of vision is represented in the visual
cortex of the left cerebral hemisphere and vice versa.
• Impulses from the superior retinal quadrants (inferior
field of vision) pass to the superior wall of the calcarine
sulcus,
• Impulses from inferior retinal quadrants (superior field
of vision) pass to the inferior wall of the calcarine
sulcus.
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Visual Area
Macular area-
• occupying approximately
posterior one-third of the visual
cortex.
• is the central area of retina and
responsible for maximum visual
acuity (keenest vision) has
extensive cortical representation
• concerned with reception and
perception of isolated visual
impressions like colour, size, form,
motion, illumination and
transparency.
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Clinical Correlation
• Crossed homonymous hemianopia
-Lesions of the primary visual
area result in the loss of vision in
the opposite visual field .
• Inferior quadrantic hemianopia -
Unilateral lesions of superior wall
of postcalcarine sulcus.
• Superior quadrantic hemianopia
Lesions involving inferior wall of
postcalcarine sulcus.
• Most common causes of these
lesions are vascular accidents,
tumours and injuries from gunshot
wounds.
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Visual field defects
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2.Secondary visual area/visual association area
(18 V2 and 19 V3,V4,V5)
1.Location:
 surrounds the primary
visual area occupies most
of the remaining visual
cortex on the medial and
superolateral surfaces of
the cerebral hemisphere
2.Afferent:
• from primary visual area.
.
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Secondary visual area/visual association area
(18 V2 and 19 V3,V4,V5)
• Relates the visual
information received from
primary visual area to the
past visual experiences
• Enabling recognize and
appreciate object
4.Clinical Correlation –
• Lesions result in a loss of
ability to recognize objects
(visual agnosia) seen in the
opposite field of vision.
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Other functional areas in the cerebral cortex
1.Taste area (gustatory area):
• located in the inferior part of the
parietal lobe, posterior to the
general sensory area for the mouth
or in the lower end of the postcentral
gyrus in the superior wall of the
lateral sulcus or in the adjoining area
of the insula (Area 43).
2.Vestibular area :
• located near that part of the
postcentral gyrus which is
concerned with the sensations of the
face.
3.Olfactory area (Area 28) :
• located in the anterior part of the
parahippocampal gyrus and uncus.
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Brodmanns area on medial surface of cerebral
cortex
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Brodmanns area on superolateral surface of
cerebral cortex
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Cerebral Dominance.
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Dominant Hemisphere
• Refers to the side concerned with the
perception and production of language/
speech.
• According to this concept, the left
hemisphere is dominant in over 90% of
people, in whom the right hemisphere is
described as the minor or non-dominant
hemisphere.
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Dominant Hemisphere
• Left hemisphere controls the right side of
the body, including the skilful right hand.
• Consequently over 90% of the adult
population is right-handed.
• During childhood, one hemisphere slowly
comes to dominate over the other
• Only after the first decade that the
dominance becomes fixed
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Revision-Brodmanns Area
• Areas 3, 1 & 2 – Primary Somatosensory Cortex (frequently referred to as Areas 3,
1, 2 by convention)
• Area 4 – Primary Motor Cortex
• Area 5 – Somatosensory Association Cortex
• Area 6 – Premotor cortex and Supplementary Motor Cortex (Secondary Motor
Cortex)(Supplementary motor area)
• Area 7 – Somatosensory Association Cortex
• Area 8 – Includes Frontal eye fields
• Area 9 – Dorsolateral prefrontal cortex
• Area 10 – Anterior prefrontal cortex (most rostral part of superior and middle
frontal gyri)
• Area 11 – Orbitofrontal area (orbital and rectus gyri, plus part of the rostral part of
the superior frontal gyrus)
• Area 12 – Orbitofrontal area (used to be part of BA11, refers to the area between
the superior frontal gyrus and the inferior rostral sulcus)
• Area 13 and Area 14* – Insular cortex1/5/2016 67
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• Area 15* – Anterior Temporal Lobe
• Area 16 – Insular cortex
• Area 17 – Primary visual cortex (V1)
• Area 18 – Secondary visual cortex (V2)
• Area 19 – Associative visual cortex (V3,V4,V5)
• Area 20 – Inferior temporal gyrus
• Area 21 – Middle temporal gyrus
• Area 22 – Superior temporal gyrus, of which the caudal part is usually
considered to contain the Wernicke's area
• Area 23 – Ventral posterior cingulate cortex
• Area 24 – Ventral anterior cingulate cortex.
• Area 25 – Subgenual area (part of the Ventromedial prefrontal cortex)
• Area 26 – Ectosplenial portion of the retrosplenial region of the cerebral
cortex
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• Area 27 – Piriform cortex
• Area 28 – Ventral entorhinal cortex, olfactory rea
• Area 29 – Retrosplenial cingulate cortex
• Area 30 – Part of cingulate cortex
• Area 31 – Dorsal Posterior cingulate cortex
• Area 32 – Dorsal anterior cingulate cortex
• Area 33 – Part of anterior cingulate cortex
• Area 34 – Dorsal entorhinal cortex (on the Parahippocampal gyrus)
• Area 35 – Perirhinal cortex (in the rhinal sulcus)
• Area 36 – Ectorhinal area, now part of the perirhinal cortex (in the rhinal
sulcus)
• Area 37 – Fusiform gyrus
• Area 38 – Temporopolar area (most rostral part of the superior and middle
temporal gyri)1/5/2016 69
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• Area 39 – Angular gyrus, considered by some to be part of Wernicke's area
• Area 40 – Supramarginal gyrus considered by some to be part of Wernicke's
area
• Areas 41 and 42 – Auditory cortex
• Area 43 – Primary gustatory cortex
• Area 44 – Pars opercularis, part of the inferior frontal gyrus & part of Broca's
area
• Area 45 – Pars triangularis, part of the inferior frontal gyrus&part of Broca's area
• Area 46 – Dorsolateral prefrontal cortex
• Area 47 – Pars orbitalis, part of the inferior frontal gyrus
• Area 48 – Retrosubicular area (a small part of the medial surface of the
temporal L.)
• Area 49 – Parasubicular area in a rodent
• Area 52 – Parainsular area (at the junction of the temporal lobe and the insula)
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