 Layers of cerebral cortex and its  variations. Surface and functional anotomy of  occipital lobe. Clinical effects of ...
› One third of the cerebral cortex is on the  exposed part of gyri remaining is buried in  sulci and gyri.› 15 to 30 billi...
› The areas of where six layers can not be  identified are called as heterotypical  different from homotypical.› Supragran...
› Superiolateraly occupies a small area  behind the parieto occipital sulcus.› Medially area behind the occipetoparietal  ...
Consists of Broadmann areas 17,18,19.   Primary visual cortex or striate cortex or    area 17    › Well devoloped layer 4...
› Stimulation or ictal activity produces simple visal hallucinations.
   Associative visual cortex:    › Parastiriate [area 18] and peristriate [area        19]    ›    receives and interpret...
› In humans occipital eye field is present in the visual association cortex concerned with reflex eye movements.
   Visual field defects:
 Unclear . Dual representation of macula in each  occipital pole. Collateral blood supply from anterior  and middle cer...
   Cortical blindness:    › Bilateral lesions of the occipital lobe there is      loss of sight and reflex closure of eye...
   Visual anasagnosia or Antons syndrome:    › Denial of blindness.    › Occurs with bilateral PCA infarcts.    › Sparing...
   Visual illusions:    › Size, shape, movement or combination of        three.    ›   Occipital lesion or in combination...
   Visual hallucination:    › Elimentary or simple visual hallucination is the      feature of striate cortex    › Includ...
   VISUAL OBJECT AGNOSIA:    › Failure to recognize objects by vision with     preserved ability to recognize them throug...
   Aperceptive visual agnosia:    › Perceived elements of object are      synthesized to whole image.    › Pick out featu...
   Left hemisphere occipital cortex    invoved in more local processing.
   ASSOCIATED VISUAL AGNOSIA:    › Is more closely related to aphasia than      primary disorder of vision.    › Patients...
• Bilateral posterior hemispheric lesions involving  occipitotemporal gyrus some times lingual gyri  and adjacent white ma...
   Charecterised by    › Simultagnosia is a disorder of visual attention      especially to peripheral field associated  ...
• Optic apraxia is inability project gaze voluntarily  in the peripheral field despite intact  occulomotor movements.
› Inability to recognise familiar faces or  pictures.› Associated with inability to memorise new  faces.› Inability to nam...
 The classic syndrome of pure alexia  without agraphia is caused by a left  posterior cerebral artery occlusion in a  rig...
   The inferior parietal lobule in the dominant    hemisphere (primarily area 39, the angular    gyms) is the association...
› Differentiated between perceptual color  disturbance or anomia› Congenital retinal color blindness is the most  common t...
› Most often the lesions are bilateral and tend to affect the upper quadrants with lesions in bilateral ventro mesial temp...
   Color anomia can be a part of pure    word blindness or anomic aphasia.
 Signing Shmidt Rimpler test A functionally blind person ignorant of  laws of reflection may have much  improved vision...
1.   Effects of unilateral disease:     ›   Contraletral homonymous hemianopia,         which may be central or peripheral...
› Visual object agnosia.3. Rt. Occipital disease:  ›   Lt. Homonymous hemianopia.  ›   Visual illusinations and hallucinat...
4. Bilateral occipital disease:  › Cortical blindness.  › Anton syndrome.  › Achro motopsia.  › Prosopagnosia [tempero-occ...
THAN Q
Occipital lobe and clinical effects of its dysfunction
Occipital lobe and clinical effects of its dysfunction
Occipital lobe and clinical effects of its dysfunction
Occipital lobe and clinical effects of its dysfunction
Occipital lobe and clinical effects of its dysfunction
Occipital lobe and clinical effects of its dysfunction
Occipital lobe and clinical effects of its dysfunction
Occipital lobe and clinical effects of its dysfunction
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Occipital lobe and clinical effects of its dysfunction

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Occipital lobe and clinical effects of its dysfunction

  1. 1.  Layers of cerebral cortex and its variations. Surface and functional anotomy of occipital lobe. Clinical effects of occipital lobar dysfunction. Differentiation between malingering and organic visual loss.
  2. 2. › One third of the cerebral cortex is on the exposed part of gyri remaining is buried in sulci and gyri.› 15 to 30 billion nerve cells.› Thickness of the cortex from 4.5 mm in the frontal area to 1.3 mm in the occipital area.
  3. 3. › The areas of where six layers can not be identified are called as heterotypical different from homotypical.› Supragranular cortex high level cortical functions.› Archicortex and paleo cortex.› Granular and agranular cortex.
  4. 4. › Superiolateraly occupies a small area behind the parieto occipital sulcus.› Medially area behind the occipetoparietal sulcus.› Inferiorly limited by collateral sulcus.› medially occipital lobe is devided in to cuneus and lingual gyrus.
  5. 5. Consists of Broadmann areas 17,18,19. Primary visual cortex or striate cortex or area 17 › Well devoloped layer 4 a thick layer of external band of ballirager. › Lips of calcarine with adjacent areas cuneus and lingual gyrus. › Perception of simple sensation color, size, shape, motion and illumination.
  6. 6. › Stimulation or ictal activity produces simple visal hallucinations.
  7. 7.  Associative visual cortex: › Parastiriate [area 18] and peristriate [area 19] › receives and interprets impulses. › Have extensive connections. › Concerned with more complex visual functions of perception, spatial orientation, visual association, and visual memory. › Stimulation produces formed or complex visual hallucinations.
  8. 8. › In humans occipital eye field is present in the visual association cortex concerned with reflex eye movements.
  9. 9.  Visual field defects:
  10. 10.  Unclear . Dual representation of macula in each occipital pole. Collateral blood supply from anterior and middle cerebral artery. Extensive cortical representation at occipital pole and depths of anterior calcarine fissure.
  11. 11.  Cortical blindness: › Bilateral lesions of the occipital lobe there is loss of sight and reflex closure of eyelids to threat and light with sparing of pupilary light reflex. › Most common cause bilateral pca infarcts. › Other causes are PRES, CJD, PML and gliomas.
  12. 12.  Visual anasagnosia or Antons syndrome: › Denial of blindness. › Occurs with bilateral PCA infarcts. › Sparing of tiny islands of vision › Patient complains of fluctuation of images as the vision is captured in spared islands of cortex.
  13. 13.  Visual illusions: › Size, shape, movement or combination of three. › Occipital lesion or in combination occipitotemporal and occipitoparietal areas. › Illusion of movement occurs with occipetotemporal lesions. › Polyopia with lesions in occipital lobe. › Palinopsia with lesions in occipitoparietal lesions.
  14. 14.  Visual hallucination: › Elimentary or simple visual hallucination is the feature of striate cortex › Includes flashes of light, luminous lightened candles, multiple stars and geomatric forms. › Complex or formed visual hallucination is a feature of association cortex or its connections › Includes objects, animals, persons and scenes.
  15. 15.  VISUAL OBJECT AGNOSIA: › Failure to recognize objects by vision with preserved ability to recognize them through touch or hearing and in the absence of impaired primary visual perception or dementia
  16. 16.  Aperceptive visual agnosia: › Perceived elements of object are synthesized to whole image. › Pick out features of the object correctly such as lines, angles,colors or movement but fail to appreciate the whole object. › Examples : spectacles › Right hemisphere particularly lingual gyrus involved in global processing of the object
  17. 17.  Left hemisphere occipital cortex invoved in more local processing.
  18. 18.  ASSOCIATED VISUAL AGNOSIA: › Is more closely related to aphasia than primary disorder of vision. › Patients can copy and match the drawing of objects but can not name them. › They can be identified by tactile or auditary modality. › have associated color agnosia and prosagnosia.
  19. 19. • Bilateral posterior hemispheric lesions involving occipitotemporal gyrus some times lingual gyri and adjacent white matter.
  20. 20.  Charecterised by › Simultagnosia is a disorder of visual attention especially to peripheral field associated inability to perform orderly visual scanning of the environment and attention to other sensory stimuli are intact. › Optic ataxia is the loss of hand eye co- ordination with difficulty in touching or reaching the objects under visual guidance.
  21. 21. • Optic apraxia is inability project gaze voluntarily in the peripheral field despite intact occulomotor movements.
  22. 22. › Inability to recognise familiar faces or pictures.› Associated with inability to memorise new faces.› Inability to name the species of birds, animals or car model.› Bilateral ventromesial occipital lesions.
  23. 23.  The classic syndrome of pure alexia without agraphia is caused by a left posterior cerebral artery occlusion in a right-handed individual All visual information enters only the right hemisphere The right visual cortex perceives the written material but cannot transmit it to the left hemisphere because of the callosal lesion
  24. 24.  The inferior parietal lobule in the dominant hemisphere (primarily area 39, the angular gyms) is the association cortex that combines the visual and auditory information necessary for reading and writing A second distinct type of alexia, classically called alexia with agraphia, results from damage to the inferior parietal lobule itself (angular gyrus and environs). This lesion renders the patient unable to read or write
  25. 25. › Differentiated between perceptual color disturbance or anomia› Congenital retinal color blindness is the most common type tested by using ishihara charts.› Acquired color blindness due to cerebral lesion is called central achromatopsia.› Associated visual field defects and prosopagnosia.
  26. 26. › Most often the lesions are bilateral and tend to affect the upper quadrants with lesions in bilateral ventro mesial temporal lobes and lower part of the striate cortex.
  27. 27.  Color anomia can be a part of pure word blindness or anomic aphasia.
  28. 28.  Signing Shmidt Rimpler test A functionally blind person ignorant of laws of reflection may have much improved vision reading an acuity chart held at his chest in a mirror 10 ft away than reading the chart 20 ft away. Optokinetic nystagmus. Photic drive on eeg and VER.
  29. 29. 1. Effects of unilateral disease: › Contraletral homonymous hemianopia, which may be central or peripheral. › Visual hallucinations.2. Left occipital disease: › Rt. Homonymous hemianopia › Alexia with out agraphia, color anomia.
  30. 30. › Visual object agnosia.3. Rt. Occipital disease: › Lt. Homonymous hemianopia. › Visual illusinations and hallucinations › loss of topographic memory and visual orientation.
  31. 31. 4. Bilateral occipital disease: › Cortical blindness. › Anton syndrome. › Achro motopsia. › Prosopagnosia [tempero-occipital] › Simultagnosia and balints syndrome [parieto- occipital]
  32. 32. THAN Q

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