Functional areas of brain

Functional areas of brain
Ravish Yadav

Important Sulci and Gyri on
superolateral surface
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Important Sulci and Gyri on medial surface
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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 ganglia
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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.7/29/2020 31

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.
• Concerned with the 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 )
•Concerned with the
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
cortex1.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 cortex
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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)
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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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