visual pathways

Question 1

visual system pathway components

Answer 1

1. temporal and nasal retina
2. optic nerve
3. optic chiasm
4. optic tract
5. pulvinar nucleus
6. lateral geniculate body
7. superior colliculus
8. optic radiation
9. primary visual cortex

Question 2

retina components

Answer 2

• rods
• cones
• ganglion cells (optic disc)

Question 3

rods

Answer 3

• dim light and peripheral vision
• rhadapsin inhibits glutamate which is continuously secreted in darkness

Question 4

compenents of rods

Answer 4

• inner
• outer (~700 discs with rhadapsin)
• rod fiber (nucleus)

Question 5

cones

Answer 5

• 3 types (red, blue, yellow)
• visual acuity and trichromatic vision

Question 6

components of cones

Answer 6

• inner
• outer (pigment-bearing discs)

Question 7

retinal cells

Answer 7

• midget cells
• parasol cells
• association neurons
• muller glial cells

Question 8

where are neural signals from the rods and cones processed

Answer 8

in retinal ganglion cells in the posterior retina

Question 9

midget cells

Answer 9

• small dendritic arbors
• small slow-moving stimuli
• not sensitive to low contrast
• color

Question 10

parasol cells

Answer 10

• large dendritic arbors
• large fast moving stimuli
• sensitive to low contrast
• no color

Question 11

association neurons

Answer 11

• amacrine cells (inhibit and excite)
• horizontal cells (inhibit)
• interplexiform cells (feeback between amacrine and horizontal cells)

Question 12

muller glial cells

Answer 12

support

Question 13

pathway to the visual cortex

Answer 13

• optic nerve to optic chiasm (hypothalamus)
• visual fields cross to lateral geniculate nucleus of the thalamus

Question 14

optic nerve portions

Answer 14

• intraocular portion
• intraorbital portion
• intra-canalicular portion
• intracranial portion

Question 15

optic tract/chiasm location

Answer 15

superior to sella turcica and pituitary gland

Question 16

what are the optic tract/chiasm susceptible to

Answer 16

secondary pituitary disorders

Question 17

pulvinar nucleus

Answer 17

• largest thalamic nucleus
• medial and dorsal to the lateral geniculate nucleus

Question 18

most fibers travel from the chiasm after splitting to lateral geniculate nucleus but 10% travel to …

Answer 18

superior colliculus and pulvinar nucleus to the primary visual cortex

Question 19

which retinal cells input info to the lower geniculate nucleus

Answer 19

• midget ganglion cells
• pasasol cells

Question 20

optic radiations

Answer 20

• geniculocalcarine fibers
• exit dorsally from lower geniculate nucleus then spread into superior and inferior bundles

Question 21

dorsal and central optic radiations travel in ? to ?

Answer 21

parietal lobe; visual cortex

Question 22

ventral optic radiations curve in an anteroinferior direction into the ?

Answer 22

anterior pole of temporal lobe

Question 23

meyers loop

Answer 23

ventral group of optic radiation fibers

Question 24

optic radiation function

Answer 24

carry information from the thalamus’s lower geniculate neuron to the primary visual cortex

Question 25

what information is processed in the primary cortex

Answer 25

- static versus moving objects - pattern recognition

Question 26

what information is processed in occipital, parietal, temporal lobe

Answer 26

- object recognition - color perception - depth - motion

Question 27

primary visual area brodmanns area

Answer 27

17

Question 28

secondary visual area brodmanns areas

Answer 28

18, 19

Question 29

visual defects

Answer 29

- retinal detachment - color vision deficiency

Question 30

retinal detachment

Answer 30

- blow to the eye - fluid accumulation - can lead to blindness

Question 31

color vision deficiency

Answer 31

- dichromatic vision (one opsin not produced) - monochromatic vision (2/3 cone opsin not produced)

Question 32

4 common neurological patterns of vision loss

Answer 32

- monocular blindness - bitemporal hemianopia - homonymous hemianopia - lesions of the primary visual cortex

Question 33

monocular blindness

Answer 33

- lesion at optic nerve - stroke (ophthalmic artery) - migraine (transient) - MS (bilateral)

Question 34

bitemporal hemianopia

Answer 34

- optic nerve compression - pituitary tumor - info from temporal visual field falls on the nasal retina - vision is missing in the outer half of left and right visual fields

Question 35

homonymous hemianopia

Answer 35

- posterior cerebral artery stroke - lesion after optic chiasm - vertical midline loss

Question 36

lesions of the primary visual cortex

Answer 36

- scotoma - hole is the visual field