Lesions of the Visual System- Graf

Question 1

Pathway lesions are very clear cut. Cognitive lesions are not so clear cut

Answer 1

???

Question 2

Patches in diabetic retinopathy

Answer 2

?????

Question 3

Glaucoma can be monocular (primarily) or biocular

Answer 3

???

Question 4

What is scotoma?

Answer 4

loss of a part of the visual field

Question 5

What is nyctalopia?

Answer 5

poor night vision (with extreme myopia, cataract, vitamin A deficiency)

Question 6

What is diplopia?

Answer 6

double vision

Question 7

What is photopic vision?

Answer 7

daylight- cone (color) vision

Question 8

What is scotopic vision?

Answer 8

night-rod (black/white) vision

Question 9

What are the normal limits of the visual field?

Answer 9

160 degrees horizontally

135 degrees vertically

Question 10

The right visual hemifield corresponds to?

Answer 10

right nasal retina and left temporal retina

Question 11

The left visual hemifield corresponds to?

Answer 11

left nasal retina and right temporal retina

Question 12

What are the optic radiations?

Answer 12

The optic radiation (also known as the geniculocalcarine tract, the geniculostriate pathway, and posterior thalamic radiation) are axons from the neurons in the lateral geniculate nucleus to the primary visual cortex.

Question 13

The optic radiations can be divided into what two pathways?

Answer 13

retrolenticular pathway

sublenticular pathway or the “temporal detour”

Question 14

The optic radiations can be divided into what two pathways?

Answer 14

retrolenticular pathway

sublenticular pathway or the “temporal detour”

Question 15

What is the Meyer’s loop?

Answer 15

they are fibers from the superior retina

Question 16

What fibers do the retrolenticular pathway represent?

Answer 16

fibers representing superior retinal quadrants

Question 17

What fibers do the sublenticular pathway represent?

Answer 17

fibers representing inferior retinal quadrants

Question 18

Describe the projection of input from the retina to the visual cortex.

The inferior halves of the retina receives what information from the visual hemifields? Where is this information transmitted to in the primary visual cortex?

Answer 18

• information from the superior visual hemifields

- information is transmitted via MEYER’S LOOP to the inferior banks (lingual gyrus) of the primary visual cortex

Question 19

Describe the projection of input from the retina to the visual cortex.

The superior halves of the retina receives what information from the visual hemifields? Where is this information transmitted to in the primary visual cortex?

Answer 19

• information from the inferior visual hemifields

- information is transmitted to the superior banks (cuneus gyrus) of the primary visual cortex

Question 20

If there is lesion of the right optic nerve, how is the visual field disrupted?

Answer 20

right eye blindness

Question 21

If there is lesion of the right optic nerve, how is the visual field disrupted?

Answer 21

right eye blindness AKA

monocular blindness

Question 22

If there is a coronal lesion of the optic chiasm, how is the visual field disrupted?

Answer 22

complete blindness

Question 23

If there is lesion in the left optic tract?

Answer 23

right temporal and left nasal region is affected AKA

bilateral right hemianopia

Question 24

If there is lesion in the left optic tract, how is the visual field affected?

Answer 24

right temporal and left nasal region is affected AKA

bilateral right hemianopia AKA contralateral homonymous hemianopsia

Question 25

If there is a lesion in right Meyer’s loop, how is the visual field affected?

Answer 25

loss of vision in the superior quadrant of the contralateral (left) half of the visual field for both eyes AKA

upper contralateral (left) quadrantic anopsia

Question 26

If there is partial lesion in the visual cortex in the lower left bank of the calcarine sulcus, how is the visual field affected?

Answer 26

deficit in the superior quadrant of the contralateral (right) visual field

Question 27

If there is partial lesion in the visual cortex in the upper right bank of the calcarine sulcus, how is the visual field affected?

Answer 27

deficit in the inferior quadrant of the contralateral (left) visual field

Question 28

If there is lesion involving both banks of the calcarine sulcus, how is the visual field affected?

Answer 28

contralateral homonymous hemianopsia, however sparing the foveal representation

Question 29

Why might macular vision be spared after posterior cerebral artery occlusion?

Answer 29

because of the dual blood supply of the primary visual cortex by the posterior and middle cerebral arteries

Question 30

Visual processing centers in the cerebral cortex are organized in two pathways: a dorsal stream and a ventral stream. What do each streams represent?

Answer 30

dorsal stream: motion, depth, spatial information

ventral stream: object vision, form, color

Question 31

What is spatial hemineglect?

Answer 31

RIGHT-sided parietal-temporal lobe lesion: TPO junction):

TPO= temporal, parietal, occipital

patients ignore their entire left visual world

Question 32

What is thought to be involved in causing neglect?

Answer 32

temporal-parietal-occipital junction

Question 33

What is Balint syndrome?

Answer 33

(bilateral parietal-temporal lobe lesions): spatial-temporal disorientation, generalized loss of attention, combining paralysis of visual fixation, optic ataxia, and impairment of visual fixation, inability to execute voluntary movement in response to visual stimuli

Question 34

What is visual agnosia?

Answer 34

deficit in object perception while vision is preserved

lesions are in the temporal lobe as well as at the temporal-occipital border

Question 35

What is achromatopsy?

Answer 35

• loss of color vision

- lesion of area V4

Question 36

What is prosopagnosia?

Answer 36

• a loss of the ability to recognize faces
• lesion in the LEFT temporal lobe

-after particular lesions of the RIGHT temporal lobe, the ability to recognize faces is preserved, however the patients are unable to gage the emotional content of facial expressions

Question 37

What is alexia?

Answer 37

the loss of ability to read

-lesion of the left occipital cortex or of the angular gyrus

Question 38

What is akinematopsy?

Answer 38

loss of perception of motion

lesion of area V5 (MT, MST)