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functional areas of cerebrum

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									Functional areas of cerebral
           cortex
                History
 Phrenology of Gall and Spurzheim
 Clinical evidences
    Broca’s area (1861)
     Jacksonian epilepsy (1864)
 Experimental evidences
    Fritsch and Hitzig (1870) --- motor cortex
     von Gudden (1870) ---- visual cortex
     Ferrier (1873) ---- auditory cortex
         “the brain, taken largely, is divided
         into its enveloping membranes, its
         medullary substance, and its
         ventricles; these last being filled
         with a vapor of special use to the
         anima or psyche, a vapor called
         „animal spirit‟.
         The brain is in continual motion by
         reason of the motions of motor
         nerves, very many of which arise
         in posterior part of the brain, and is
         subject to continual effects from
         the motions of sensory nerves
         forward, where are located the
         cerebral organs suited to receive
         the sensory forms.”
                                             - Albertus Magnus
                                                (1206-1280)
Ref : Albert the Great on the Classification and Localization of the Internal Senses
Nicholas H. Steneck
Isis, Vol. 65, No. 2 (Jun., 1974), pp. 193-211
(article consists of 19 pages)
Published by: The University of Chicago Press on behalf of The History of Science Society
Stable URL: http://www.jstor.org/stable/229370
Phrenology
                 • is a
                hypothesis
                stating that
                      the
                personality
                  traits of a
                person can
                 be derived
                   from the
               shape of the
                     skull.
             • Developed
                by German
                 physician
                     Franz
               Joseph Gall
                in 1796,the
                  discipline
                  was very
                 popular in
                   the 19th
                 century. In
                     1843,
   Pierre Paul
     Broca
• Pierre Paul Broca
  (28 June 1824 – 9 July
  1880) was a French
  physician, anatomist, and
  anthropologist.
• He was born in Sainte-
  Foy-la-Grande, Gironde.
• best known for his
  research on Broca's area,
  a region named after him.
                  Broca..
• Discovery by studying the brains of
  aphasic patients.
• His first patient in the Bicêtre Hospital was
  Leborgne, nicknamed "Tan" due to his
  inability to clearly speak any words other
  than "tan".
• Broca determined that Tan had a lesion
  caused by syphilis in the left cerebral
  hemisphere.
• Photographs showing lateral views of the brains
  of Leborgne (left) and Lelong (right). Broca
  preserved the organs by immersing them in
  alcohol; he then donated them to the Musée
  Dupuytren in Paris.
• Although history credits this discovery to Broca,
  another French neurologist, Marc Dax, made
  similar observations a generation earlier.
• He submitted his discovery, based on the
  observations of three patients in Montpellier, to
  the French Academy of Sciences and two
  previous notes were published in 1836, 25 years
  before Paul Broca's more famous description.
• In 1863, Gustave Dax, the son of Marc Dax,
  published his father's work on the subject, two
  years after Paul Broca's presentation
John Hughlings Jackson
           • English neurologist,
             born April 4, 1835,
             Providence, Green
             Hammerton,
             Yorkshire ; died
             October 7, 1911,
             London.
• In 1865 Jackson married his cousin
  Elizabeth Dade Jackson
• She died childless of a cerebro vascular
  disorder in 1876.
• After his wife died he became a recluse
  and suffered from vertigo and migraine.
His wife suffered from Jacksonian epilepsy!

• One of Jackson‟s most outstanding
  contributions to the neurosciences was his
  contention that function is localized to
  areas of the cerebral cortex
           Dog – cerebrum
• By 1870 he was certain of his contention,
  and it was in the same year that Gustav
  Theodor Fritsch (1838-1927) and Julius
  Eduard Hitzig (1838-1907) showed
  experimentally that electrical stimulation of
  the cortex produced contralateral limb
  movements.
                 Brodmann - 1909
• Rarely in the history of neuroscience has a
  single illustration been as influential as the
  cytoarchitectonic map of the human brain
  published by Korbinian Brodmann in his
  monograph from 1909.




Nat Rev Neurosci. 2010 Feb;11(2):139-45. Epub 2010 Jan 4.
                                    Korbinian
•   Born in Germany and as he
    proceeded in education he was
                                    Brodmann
    eventually attracted to Oscar
    Vogt (1870-1959) who induced
    him to devote his life to
    neurology and psychiatry. But
    in 1900-1901, Brodmann came
    into contact with Alois
    Alzheimer (1864-1915) who
    launched him into his life’s
    work in neuroanatomy.
    Brodmann is responsible for
    establishing the basis upon
    which the present day science
    of comparative
    cytoarchitectonics of the
    mammalian cortex rests. All
    confusion of brain area
    nomenclature disappeared with
    Brodmann’s contribution.
• Original
  cytoarchitectonics of
  human brain as
  published by
  Borodman




                          Ref : Comparative Localization Studies in the Brain
                          Cortex, its Fundamentals Represented on the Basis of
                          its Cellular Architecture- Brodman 1909.

                          Korbinian Brodmann (1912). "Neue Ergebnisse über
                          die vergleichende histologische Localisation der
                          Grosshirnrinde mit besonderer Berücksichtigung des
                          Stirnhirns". Anatomischer Anzeiger Supplement 41:
                          157–216.
              TYPES


Motor areas   Sensory areas     Association
                                  areas

                              75% of total surface of
                              human cerebral cortex
Functional areas of Frontal lobe

• primary Motor Area

• Premotor Area

• Supplementary Motor Area

• Frontal Eye Field
 Primary
                          4
motor area




 • Has pyramidal cells
   – Including Cells of Betz
 • 40% of pyramidal fibers arise from this area
              Pyramidal tract
• Designates only those fibers that course
  longitudinally in the pyramid of medulla
  oblongata
• Of all the fiber bundles of brain – pyramidal
  tract has been known for the longest time.
• First accurate description – by Turck – 1851
• Only direct connection between cerebral
  cortex – spinal cord
                            Confusion !
  • Traditionally – it is thought that it originates
    from large motor cells of Betz- 5th layer of
    Precentral convolution
  • 1 million axons – in medullary pyramid.
  • BUT – only 25000- 30000 Betz cells are
    present.


Ref: Lassek. A M, „the pyramidal tract‟, Sppringerlink, IL, Charles C Thomas,
1954.
              In Monkeys

                       40%    • Parietal lobe

• Pyramidal tract -     31%
                              • Motor area

                      29%
                              • Premotor area
• Motor area of cerebral cortex
  – Definition – physiologically –
  – As region of electrically excitable cortex from
    which isolated movements can be evoked by
    stimuli of minimal intensity.
  Delicate movements = large rapresentation

                                 Representation
                                 of body parts in
                                 motor cortex –
                                      motor
                                   homunculus




Latin for "little human", from
the diminutive of homo;
plural: "homunculi"
• Loss of neurons
  results in loss of
  muscle power in
  contra lateral side
                                 6
                                           Premotor
                                             area




• Concerned with
   –   individual personality
   –   Depth of emotions
   –   Social, moral, ethical awareness,
   –   Concentration
   –   Orientation
   –   Foresightedness.
                                   Supplementary
                                     motor area




Induce
  – gross movements / contralateral movements
  – Tonic contractions of limbs( bilateral)
  – Contraversive movements of head and eyes with
    tonic contraction of contralateral arm
  – Sometimes inhibition of voluntary motor activity and
    vocal arrest
• Motor cortex – is organised not in terms of
  individual muscles but of movements
• i.e. Coordinated contraction of groups of
  muscles
  – Hughlings Jackson & Sherrington
                                         Frontal eye
                   8                        field




• Causes
  – deviation of both eyes to opposite side
  – Voluntary scanning of eyes
    • Independent of visual stimuli
                              Motor speech
                                  area



                 44
            45




• Dominant hemishere – left
• Speech / vocalization
• Motor aphasia
Functional areas in parietal lobe
•   Primary sensory area
•   Secondary sensory area
•   Secondary association area
•   Sensory speech area of Wernicke
Primary sensory                     3a, 3b, 1, 2 SI

area
                          3, 1, 2




Representation – upside down
Concerned with
  Exteroception
  proprioception
                         4   6


                                 8




• Afferents
  – VPL
              Thalamus
  – VPM
Secondary
sensory area




•   Face area – anterior most
•   Sacral area – posterior most
•   Whole body – bilateral representaion
•   Concerned more with pain preception
   Sensory
association area

                         5       7




 • Concerned with stereognosis
  Sensory speech
 area of Wermicke




                              40     39




• Left dominant hemisphere
• Interpretation of language through visual
  and auditory input
  Functional areas of temporal
              lobe

• Primary auditory area

• Secondary auditory area
Primary auditory
Secondary auditory
area
area




                            41
                                 42




 •• Interpretation of words
     Loudness, quality, pitch
   Functional areas of occipital
               lobe

• Primary visual area

• Secondary visual area
Primary visual
area
Secondary visual
area



                   18
                        17




  • Vision
Visual area
   map
            Gustatory area
• Inferior part of parietal lobe
• Posterior to general sensory area for
  mouth
• Brodmann area 43
           Vestibular area
• Postcentral gyrus
            Olfactory area
• Anterior part of parahippocampal gyrus
  and uncus
• Brodmann area 28
                                But . .
• Brodmann (1907), it is true, prepared a
  map of the human brain which has been
  widely reproduced, but, unfortunately, the
  data on which it was based was never
  published
         • von Bonin and Bailey 1925




Ref : Gerhardt von Bonin & Percival Bailey (1925). The Neocortex of
Macaca Mulatta. Urbana, Illinois: The University of Illinois Press.
 Techniques for mapping brain
          function
• Most techniques involve
  – Detecting and mapping the local changes in
    cerebral blood flow
  – Important imaging modality
    • Positron emission tomography (PET),
    • Single-photon emission computerized tomography
      (SPECT),
    • functional magnetic resonance imaging (fMRI).
    • Near infrared spectroscopy ( NIRS)
  – Others
       – EEG
         Magnetoencephalography - MEG
  PET
scanning
 • Showing
   motor
   cortex
MRI – ear to ear
fMRI - Tractography 3D
    reconstruction
fMRI
fMRI
       • Motor cortex of
         brain highlighted
• fMRI highlighting Broca‟s area
Tractography




 Showing association fibres
Tractography




 Showing association fibres
Where are areas 13, 14, 15, 16,
       27, 49, 50, 51?




        Present only in monkeys
                                                                          •   Brodmann areas for human & non-human primates
•   Brodmann areas for human & non-human primates
                                                                          •   Area 27 - Piriform cortex
•   Areas 3, 1 & 2 - Primary Somatosensory Cortex (frequently
    referred to as Areas 3, 1, 2 by convention)                           •   Area 28 - Posterior Entorhinal Cortex
•   Area 4 - Primary Motor Cortex                                         •   Area 29 - Retrosplenial cingulate cortex
•   Area 5 - Somatosensory Association Cortex                             •   Area 30 - Part of cingulate cortex
•   Area 6 - Premotor cortex and Supplementary Motor Cortex               •   Area 31 - Dorsal Posterior cingulate cortex
    (Secondary Motor Cortex)(Supplementary motor area)                    •   Area 32 - Dorsal anterior cingulate cortex
•   Area 7 - Somatosensory Association Cortex                             •   Area 33 - Part of anterior cingulate cortex
•   Area 8 - Includes Frontal eye fields                                  •   Area 34 - Anterior Entorhinal Cortex (on the
•   Area 9 - Dorsolateral prefrontal cortex                                   Parahippocampal gyrus)
•   Area 10 - Anterior prefrontal cortex (most rostral part of superior   •   Area 35 - Perirhinal cortex (on the Parahippocampal gyrus)
    and middle frontal gyri)                                              •   Area 36 - Parahippocampal cortex (on the Parahippocampal
•   Area 11 - Orbitofrontal area (orbital and rectus gyri, plus part of       gyrus)
    the rostral part of the superior frontal gyrus)                       •   Area 37 - Fusiform gyrus
•   Area 12 - Orbitofrontal area (used to be part of BA11, refers to      •   Area 38 - Temporopolar area (most rostral part of the
    the area between the superior frontal gyrus and the inferior              superior and middle temporal gyri)
    rostral sulcus)                                                       •   Area 39 - Angular gyrus, considered by some to be part of
•   Area 13 and Area 14* - Insular cortex                                     Wernicke's area
•   Area 15* - Anterior Temporal Lobe                                     •   Area 40 - Supramarginal gyrus considered by some to be
•   Area 17 - Primary visual cortex (V1)                                      part of Wernicke's area
•   Area 18 - Secondary visual cortex (V2)                                •   Areas 41 & 42 - Primary and Auditory Association Cortex
•   Area 19 - Associative visual cortex (V3)                              •   Area 43 - Subcentral area (between insula and
                                                                              post/precentral gyrus)
•   Area 20 - Inferior temporal gyrus
                                                                          •   Area 44 - pars opercularis, part of Broca's area
•   Area 21 - Middle temporal gyrus
                                                                          •   Area 45 - pars triangularis Broca's area
•   Area 22 - Superior temporal gyrus, of which the caudal part is
    usually considered to contain the Wernicke's area                     •   Area 46 - Dorsolateral prefrontal cortex
•   Area 23 - Ventral Posterior cingulate cortex                          •   Area 47 - Inferior prefrontal gyrus
•   Area 24 - Ventral Anterior cingulate cortex                           •   Area 48 - Retrosubicular area (a small part of the medial
                                                                              surface of the temporal lobe)
•   Area 25 - Subgenual cortex
                                                                          •   Area 52 - Parainsular area (at the junction of the temporal
•   Area 26 - Ectosplenial area
                                                                              lobe and the insula)
Thank you

								
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