Damages to the visual system

Question 1

what does a cut to the right optic nerve do?

Answer 1

1) cause right monocular blindness

Question 2

what does a cut to the optic chiasm do?

Answer 2

2) cause bitemporal blindness
this is when both temporal fields are damaged (the outside ones)

Question 3

what does a cut to the right optic tract do?

Answer 3

3) left homonyous hemianopia (left visual field blindness)

Question 4

what does a cut to 4 do?

Answer 4

4) left homonyous hemianopia with macular sparing (preserves vision in the center of the visual field)

Question 5

what are the two sides of the retina?

Answer 5

nasal (inside of the retina so inside half of visual field) and temporal (outside of retina so outside of visual field)

Question 6

patient DB had?

Answer 6

left homonymous hemianopia with macular sparing and blindsight

(DB skips V1)

Question 7

What is akinetopsia?

Answer 7

absence of motion vision
- damage to V5 - extreme

Question 8

What is Achromatopsia?

Answer 8

absence of colour vision - see greys/dream in greys
due to damage to V4

Question 9

What is visual Agnosia?

Answer 9

failure of recognition
due to damage to pathways to occipital lobe (which assembles incoming vision)

Question 10

what is apperceptive agnosia?

Answer 10

failure of recognition due to failure of perception - struggle to see shapes

• poor copying/ matching

can look like peppery mask

Question 11

what can cause apperceptive agnosia?

Answer 11

carbon monoxide poisoning/ mercury poisoning

Question 12

Dorsal Simultagnosia?

Answer 12

failure of object recognition due to spatial perceptual impairment
- can recognise objects but no more than 1
could be in different spatial positions

Question 13

Ventral simultagnosia?

Answer 13

failure of object recognition due to complex perceptual impairment
- can only identify 1 object but knows there are multiple unidentifiable objects

Question 14

where and what is the dorsal stream?

Answer 14

located in the parietal lobe
is important for spatial recognition - of objects etc

Question 15

where and what is the ventral stream?

Answer 15

located in the temporal cortex - temporal lobe
is important for object recognition (what)

Question 16

what is blindsight?

Answer 16

patients can point to objects they swear they cannot see - due to damage in temporal lobe

(can locate object they ‘can’t’ see)

Question 17

what does damage to the middle and inferior temporal gyrus do?

Answer 17

• achromatopsia
• akinetopsia
• ventral simultagnosia
• associative agnosia (difficulty understanding the meaning of what they are seeing

Question 18

what does damage to the superior temporal gyrus do?

Answer 18

auditory region…
- deafness
- wekenickes aphasia
- auditory agnosia

Question 19

Damage to the pathway from the right lateral geniculate nucleus to the right primary visual cortex results in…

Answer 19

homonymous hemianopia

Question 20

what is associative agnosia?

Answer 20

failure of recognition - but no deficit in perception
- difficulty with the meaning/understanding of what they are seeing

Question 21

difference between associative and apperceptive agnosia?

Answer 21

patients with associative agnosia are able to copy/ match/ draw objects but patients with apperceptive agnosia cannot

associative agnosia is the highest form of agnosia

Question 22

why do patients with apperceptive agnosia sometimes see a peppery mask?

Answer 22

they are scotoma all over the visual field… V1 Retinotopically mapped so scotomas are present all over this visual field.