focuses on clinical aspect

1. Occipital Lobe
Anatomy and Function
with clinical correlation
By Dr Srimant Pattnaik, DM PDT
Neuromedicine , BIN

10. Lesions in the occipital lobe
• Lesion of the primary visual area
• Lesion of the dorsal stream
• Lesion of ventral stream

11. Lesions of primary visual cortex
1. Field defects
2. Cortical blindness
3. Anton ‘ s syndrome

12. FIELD DEFECTS

13. • Binocular field defect usually localizes to or
beyond optic chiasm
• Retrochiasmal lesions are usually
homonymous hemianopia
• Bilatreal optic nerve or retinal disease can
produce bilateral field defect
• Retinal disease has ophthalmoscoic finding
• Optic nerve problem has acuity problem

15. left lower bank of calcarine sulcus
Left upper bank of calcarine sucus

16. case
• A patient recovering
from a right
hemipareisis, presented
to hospital with right
sided visual disturbance

18. Half moon or temporal crescent
syndrome

19. Cortical blindness
• Conceptualized as bilateral homonymous hemianopia.
Clinically blind.
• Due to blockage of bilateral PCA or distal Basilar artery
• Bilateral Area 17 involvement
• Central vision may be present (macular sparing):
reason for optokinetic nystagmus
• Pupilary reflex present
• Menace reflex ±
• VEP : no cortical potential
• EEG : loss of alpha rythm

20. • Visual imagination and visual imagery preserved
• Less complete bilateral lesion leave the patient
with varying degrees of visual perception
• There may be visual hallucination of either
complex or elementary type
• Recovery occurs in a regular fashion from cortical
blindness through visual agnosia and partially
impaired perceptual function to recovery
• After recovery , there may be p[roblems of visual
fatigue,fusion or fixation (3F’s)

21. Anton syndrome
• Visual Anosognosia : self unawareness of
visual deficit. Denies blindness
• Iinvolvement of primary visual area along with
visual association area
• Behaves as if he can see
• Confabulates. Has excuses for blindness

22. Inverse Anton Syndrome
• Also known as Blindism or Blindsight
• As such patient can not see but eye movements
are noticed in response to stimulus such as
flashes of light
• Due to nonconscious visual processing
• Pathways
– Retino tectal
– Retino tecto pulvino extrastriate
– Geniculoextrastriate
• Simulates hysterical blindness

23. Riddoch syndrome
• Cortical blindness but area V5 is spared
• Otherwise blind Patient can percieve moving
objects
• Hypothesis is of a direct connection between
LGB or Pulvinus to V5

24. Lesions of ventral stream
1. Visual object agnosia
2. Colour vision abnormality
3. Prosopagnosia
4. Pure Alexia

25. VISUAL OBJECT RECOGNITION
VISUAL STIMULI
PRIMARY SKETCH
VIEWER CENTERED REPRESENATION
OBJECT CENTERED REPRESENTATION
SEMANTIC CONCEPTUAL FIELD
VISUAL ANALYSIS
PHONOLOGICAL LEXICON

26. SEMANTIC-CONCEPTUAL SYSTEM
PRIMARY SKETCH-2D
VIEWER CENTERED SKETCH-2.5D
OBJECT CENTERED SKETCH-3D
MARR’S MODEL OF VISUAL
OBJECT RECOGNITION

27. Visual Object Agnosia
• Apperceptive Visual agnosia
– Perceptual categorization defect
• Associative visual agnosia

28. Apperceptive visual agnosia
VISUAL STIMULI
PRIMARY SKETCH
VIEWER CENTERED REPRESENATION
OBJECT CENTERED REPRESENTATION
SEMANTIC CONCEPTUAL FIELD
VISUAL ANALYSIS
PHONOLOGICAL LEXICON

30. Apperceptive visual agnosia
• Localization :
• bilateral lesion of calcarine cortex
• Occipitotemopral regions
• Pathology: mostly ischemic
• Most commonly seen during recovery from
cortical blindness

31. Clinical feature
• Pick out details of the object in fragments i.e
lines adges, intensity but fail to identify the
whole picture
• They can not name objects presented to them
or draw them or match them
• Mostly act as blind but avoid obstacles while
walking

32. Besdside tests
• Match test
• Figure copying test

33. Match test

34. Figure copying test

35. Perceptual categorization defect
VISUAL STIMULI
PRIMARY SKETCH
VIEWER CENTERED REPRESENATION
OBJECT CENTERED REPRESENTATION
SEMANTIC CONCEPTUAL FIELD
VISUAL ANALYSIS
PHONOLOGICAL LEXICON

36. Perceptual categorization defect:contd

37. Perceptual categorization defect:
contd
• Localization: right parietal lobe
• Patient can appreciate objects , match them
and and recognize them later as long as they
are presented in same conventional
orientation

38. tests
VOSP
Incomplete letter test
Silhouettes
BORB
Gollin figures
Unusual view test
Foreshortened match

40. silhouettes

41. Unusual view test

42. Gollin figures

43. Foreshortened match

44. Associative visual agnosia
VISUAL STIMULI
PRIMARY SKETCH
VIEWER CENTERED REPRESENATION
OBJECT CENTERED REPRESENTATION
SEMANTIC CONCEPTUAL FIELD
VISUAL ANALYSIS
PHONOLOGICAL LEXICON

45. SEMANTIC-CONCEPTUAL SYSTEM
PRIMARY SKETCH-2D
VIEWER CENTERED SKETCH-2.5D
OBJECT CENTERED SKETCH-3D
MARR’S MODEL OF VISUAL
OBJECT RECOGNITION

46. • Perception is stripped of meaning
• Patient can copy , match figures still can not
say what it is
• Can identify if object is presented by any other
modality
• Localized to bilateral posterior hemisphere
involving fusiform ot occipitotemporal gyri,
sometimes lingual gyrus and adjacent white
matter

47. Tests
• Questionnaire
• Sorting of stimuli
• Matching visually dissimilar objects according
to similar function
• Real and unreal objects
• Pyramids and palm trees test

51. Optic aphasia
VISUAL STIMULI
PRIMARY SKETCH
VIEWER CENTERED REPRESENATION
OBJECT CENTERED REPRESENTATION
SEMANTIC CONCEPTUAL FIELD
VISUAL ANALYSIS
PHONOLOGICAL LEXICON

52. • Optic aphasia or optic anomia, an
intermediate between agnosia and aphasia
• Localization: left occipitotemporal area
• Can not name object presented visually but
can recognise when given cue
• Preserved recpognition of the objects
differentiates frm associative agnosia
• Recognition with auditory or tactile cue
differentiates it from anomic aphasia

53. Face recognition

55. test
• Face identification from photographs
• Benton facial recognition test

56. Prosopagnosia
• Difficulty in recognising familiar faces
• Recognise faces from a singular feature like
glasses , beards etc or non visual cues like voice
or social context
• Apperceptive vs associative
• Localization
– B/L damage to fusiform & lingual gyri
– U/L Rt OP lesion
– B/L or U/L anterior temporal lesion

57. Causes of Prosopagnosia
• Congenital
– Hereditary : autosomal dominant inheritance
– Autistic spectrum disorder
• Acquired
– Stroke
– Herpes encephalitis
– Alzheimer
– Carbon monoxide poisoining

60. COLOUR STIMULI
COLOUR
DISCRIMINATION
COLOUR
CATEGORISATION
SEMANTIC CONCEPTUAL
FIELD
COLOR NAMING
ACHROMATOPSIA
COLOUR
AGNOSIA
COLOUR
AMNESIA

64. Cerebral Achromatopsia
• Localization : bilateral or nondominant inferior
occipito temporal lesions that damage lingual
and fusiform gyri sparing of calcarine cortex

65. COLOUR AGNOSIA
• Colour is stripped off its meaning
• Can see and discriminate though
• Can not point or paint
• Inferomedial aspect of dominant occipital anfd
temporal lobe

66. Colour Amnesia
• Defect in colour object association
• Can see, discriminate and point
• Can not paint
• Dominant hemisphere lesions

67. Colour Anomia
• Basically the optic aphasia for colours
• Defective naming only

68. ACHROMATOPSIA COLOUR
AGNOSIA
COLOUR
AMNESIA
COLOR
ANOMIA
ISHIHARA
CHART
COLOUR
PLATE
NAMING
POINTING TO
COLOUR
MATCHING
COLOUR
CONCEPTUAL
COLOUR
NAMING
COLOUR
PAINTING

69. simultanagnosia
• Inability to comprehend a complex visual
scene despite being able to comprehend
individual items
• Divided into
• Ventral
• Dorsal

70. SIMULTANAGNOSIA
DORSAL VENTRAL
LOCALIZATION B/L OCCIPITOPARIETAL LEFT OCCIPITOTEMPORAL
PATHOPHYSIOLOGY RESTRICTED VISUAL
ATTENTION
SLOW VISUAL PROCESSING
CLINICALLY BLIND NOT SO
LEVEL OF PERCEPTION LIMITED TO ONE OBJECT SEVERAL OBJECTS
PERCIEVED, ONE
RECOGNIZED
SCATTERED DOT
COUNTING
NOT ABLE TO DO ABLE TO DO
WORD READING CAN NOT READ WORDS READS BUT LETTER BY
LETTER

71. Tests of ventral Simultanagnosia
Mixed figure testing Cookie theft picture

72. Disorders of Dorsal stream
1. Balint Syndrome
2. Visual disorientation
3. Akinetopsia
4. Astereopsis
5. Visual extinction

73. Balint syndrome
• Occurs due to lesion in b/l parieto occipital
lesion in the convexity of the hemisphere
• Components
– Dorsal simultanagnosia
– Oculomotor apraxia
– Optic ataxia

74. Dorsal Simultanagnosia
• Due to restriction of visual attention
• Perception is limited to point of fixation
without the awareness of presence of other
parts
• Miss forest for trees.
• Functionally blind as they find it difficult to
move about

77. Oculomotor apraxia
• Not a true apraxia as the higher level motor
control is intact
• Also known as psychic paralysis of gaze
• Defective vision for action
• Deficit is a difficulty in shifting visual attention
to appropriate target

78. Optic ataxia

79. Optic ataxia

80. • Inability to reach a target under visual
guidance
• Defective action for vision
• No difficulty in touching body parts
• Tested by asking the patient to touch
examiner’s ear followed by touching own ear

81. Visual disorientation
• Error in judging the location and distance of
an object, and in judging the relative distance
between the two objects
• Bump into things while walking
• Difficulty in finding door handle
• Problem arises when things are placed at
different level

82. • Difficulty in reaching things becomes difficult,
mimics optic ataxia
• However, visual disorientation improves with
repeated attempts, differentiating from optic
ataxia

83. Astereopsis
• Loss of depth perception
• Depth is computed from binocular visual
information
• Retinal disparity is processed by the dorsal
stream
• Area 18 is primarily concerned with stereopsis
• Abnormality is seen due to bilateral damage,
more to the right side

84. astereopsis

85. akinetopsia

86. • Aquired defect of motion perception
• Sees moving people here and there
• Difficulty in pouring water from a cup to bottlr
as the water appears as ice

87. Visual extinction

88. Visual hallucination
• Positive visual phenomena in absence of external stimuli
• Simple formed hallucination
• Light dots, bars, lines , stars, fog, coloured senasation
• Mostly after occpital stroke: good recovery
• Psychiatric conditions
• Multicoloured wth spherical or circular pattern seen in
Occipital epileptic seizure
• Degenerative : AD,DLB
• Infective: CJD-Heidenhain variant
• Unformed hemifield hallucination post exercise : occiptal
lobe tumor

89. Peduncular Hallucinosis
• Charcot – Willebrand syndrome
• Vivid,colourful,formed hallucination of
p[eople and animal
• Usually hypnogogic
• Pseudohallucinosis as patient knows they are
unreal
• Also seen in midbrain lesion as a release
hallucination

90. Charles Bonnet Syndrome
• Seen in patients with visual loss due to
ophthalmological condition
• Well defined, organized and vivid scenes of
animals, flowers and people
• Also a pseudohallucination
• Can be abolished by repeated closing and
opening of eyes
• Deafferentiation of visual assdociation areas
leading to a form of phantom vision

91. Miscellaneous Positive visual
phenomena
• Metamorphopsia( distortions of shape)
• scintillating scotomas
• Teichopsia( irregular shapes)
• macropsia and micropsia
• palinopsia (perseveration of visual images)
• Visual allesthesia (spread of a visual image from a
normal to a hemianopic field)
• polyopia (duplication of objects)
• All these phenomena are disturbances of higher visual
perception rather than agnosias