Functional areas of brain.2015.dk

FUNCTIONAL AREAS OF BRAIN

DR.DEEPAK N.KHEDEKARLTMMC &GH

SION-MUMBAI-22

JAN-2016

1/5/2016 1Dr.Deepak N.Khedekar.LTMMC & GH,SION

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Important Sulci and Gyri on superolateralsurface


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Important Sulci and Gyri on medial surface

1/5/2016Dr.Deepak N.Khedekar.LTMMC & GH,SION

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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 Brodmannsfunctional 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

lobule2.Affrerents :• Premotor area (Area 6) • Somesthetic or

somatosensory cortex• Thalamic nucleus(VPL),

(which receives info. from cerebellum)

Basal ganglia1/5/2016 10

Dr.Deepak N.Khedekar.LTMMC & GH,SION ,MUMBAI.22

Primary motor area-Area 43.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,pharynxand 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,inferiorfrontal 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 (substantianigra)

Cortico-olivary (olivarynucleus 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 area1/5/2016 24


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

2.Associated functions:

• 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


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 paracentrallobule 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.

3.Clinical Correlation:• 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 22.Associated functions

3.Clinical Correlation:• Lesions of primary sensory

area lead to… loss of appreciation of

exteroceptive andproprioceptive 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.2.Associated functions:• 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 seeing1/5/2016 40



• 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 hemisphereoccupying…

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 )

2.Associated functions:• Concerned with the

interpretation of language through visual and auditory input.

• An essential zone for constant availability of the learned word patterns.

• Angular and supramarginalgyri 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'sarea 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'sspeech 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.

4.Clinical Correlation 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 67Dr.Deepak N.Khedekar.LTMMC & GH,SION

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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 rhinalsulcus)

• Area 37 – Fusiform gyrus

• Area 38 – Temporopolar area (most rostral part of the superior and middle temporal gyri)1/5/2016 69



• 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'sarea

• 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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