The Occipital Lobe

Question 1

What is the dorsal stream?

Answer 1

• The where/how stream

- Visual guidance of movements

Question 2

What is the ventral stream?

Answer 2

• The what stream

- Object perception (including colour)

Question 3

What are the five categories of vision?

Answer 3

• Vision for action (parietal visual areas in dorsal stream; reaching, ducking, catching)
• Action for vision (visual scanning, eye movements and selective attention)
• Visual recognition (temporal lobes; object recognition)
• Visual space (parietal and temporal lobes; spatial location)
• Visual attention (selective attention)

Question 4

What is monocular blindness?

Answer 4

• Loss of vision in one eye

- Results from destruction of retina or optic nerve

Question 5

What is bitemporal hemianopia?

Answer 5

• Loss of vision from both temporal fields (lateral vision)

- Results from lesion to medial region of the optic chiasm

Question 6

What is nasal hemianopia?

Answer 6

• Loss of vision of one nasal field

- Results from lesion of the lateral chiasm

Question 7

What is homonymous hemianopia?

Answer 7

• Blindness of one entire visual field
• Results from a complete cut of the optic tract
• Damage to LGN or V1

Question 8

What is macular sparing?

Answer 8

• Results from lesion to occipital lobe
• Sparing of central or macular region of visual field
• Differentiates lesions of optic tract or thalamus from cortical lesions
• Macular sparing occurs only after lesions to the visual cortex

Question 9

What is quadrantanopia of hemianopia?

Answer 9

• Results from lesion to the occipital lobe

- Complete loss of vision of one-quarter or one-half of the fovea

Question 10

What are field defects?

Answer 10

• Scotomas - small blind spots
• Results from small lesions to occipital lobe
• Visual system is good at overcoming these blind spots

Question 11

What is blindsight?

Answer 11

-Perception of motion and location without perceiving content

Question 12

What is visual form agnosia?

Answer 12

• Inability to recognize line drawings of objects

- Bilateral damage to LO region and tissue between parietal and occipital lobes

Question 13

What is optic ataxia?

Answer 13

• Deficit in visually guided hand movements

- Bilateral hemorrhages in occipito-parietal regions

Question 14

Prosopagnosia is caused by a lesion in which brain area?

Answer 14

-Right occipito-temporal lesion

Question 15

Alexia is caused by a lesion in which brain area?

Answer 15

-Left occipito-temporal lesion

Question 16

What is apperceptive agnosia?

Answer 16

• Deficit in ability to develop percept of an object of objects
• Can describe components of object but cannot say what the whole thing is
• Bilateral damage to lateral parts of occipital lobes

Question 17

What is simultagnosia?

Answer 17

-Unable to perceive more than one object at a time

Question 18

What is associative agnosia?

Answer 18

• Can perceive objects, but cannot identify them
• No memory of objects
• Lesions to anterior temporal lobes

Question 19

Damage to what area causes alexia? What agnosias is alexia a form of?

Answer 19

• Damage to left fusiform and lingual areas
• Form of object agnosia (inability to construct perceptual wholes from parts) OR
• Form of associative agnosia (word memory is damaged or inaccessible)