Visual Pathway - Lecture 8

Question 1

what is the visual pathway

Answer 1

amount you can see w/o head or eye movement

Question 2

retina is considered

Answer 2

in quarters (quadrants)

Question 3

what do the retinal elements in any quadrant represent

Answer 3

visual field that is opposite to it in the physical world

Question 4

central visual pathways

Answer 4

optic nerve and tract

lateral geniculate nucleus

superior collicus

accessory optic tract

Question 5

optic nerve and tract

Answer 5

axons of retinal ganglion cells collect to form a tract know as the optic nerve

Question 6

optic chiasm

Answer 6

crossing point

point at which some fibers from each side of the visual field decussate

Question 7

what does each optic tract carry

Answer 7

signals from one half of the visual field

Question 8

left optic tract carries

Answer 8

visual info from the right visual field of both eyes

Question 9

how do visual afferents continue

Answer 9

as the optic tract

Question 10

lateral geniculate nucleus

Answer 10

largest area of the 3 areas that the optic tract projects to

Question 11

where is LGN

Answer 11

caudal and lateral to thalamus

Question 12

LGN has

Answer 12

6 layers

Question 13

6 layers of LGN

Answer 13

3 for the ipsilateral eye

3 for the contralateral eye

Question 14

what do neurons from LGN project

Answer 14

to the primary visual cortex (area 17) of the occipital lobe

Question 15

superior collicus

Answer 15

optic tract sends a smaller projection to the superior collicus

Question 16

where do fibers go from superior collicus

Answer 16

sent to contralateral side and other areas of the brain

Question 17

where does info from the superior collicus help generate

Answer 17

appropriate eye movement

Question 18

how are receptive field of the superior collicus

Answer 18

large for movements that are unidirectional horizontal movements from the central to the peripheral fields

Question 19

accessory optic tract

Answer 19

some fibers seperate from the optic tract

project to optic nuclei, vestibular nuclei and the pons

Question 20

where do fibers go from the pons –> accessory optic tract

Answer 20

projections ascend to the cerebellar flocculus

helps to control eye movement

Question 21

cortical projections

Answer 21

pathways from LGN to the visual cortex

project as the optic radiations to area 17 in the occipital lobe

Question 22

where to optic radiations travel

Answer 22

posteriorly through Wernike’s area in the temporal lobe

Question 23

what can lesion to cortical projection cause

Answer 23

speech and visual field deficits

Question 24

where is the visual cortex

Answer 24

deep w/in occiput

gets info from LGN

Question 25

visual cortex is areas

Answer 25

17-19

Question 26

occipital lobe boundaries

Answer 26

difficult to define

many variations

Question 27

area 17 receives

Answer 27

projections from other areas

Question 28

what is considered the major gateway for visual info from the cortex

Answer 28

area 17

Question 29

how many layers does the visual cortex have

Answer 29

8

Question 30

how is area 17 arranged

Answer 30

topographically

mapping the visual field of the retina

Question 31

receptive fields

Answer 31

retinal cells and their related pathways

sensitive to specific stimuli in specific patterns

Question 32

what can receptive fields be responsive to

Answer 32

concentric circles

left to right

right to left

center to periphery

light to dark

Question 33

visual cortex is the first opportunity

Answer 33

for true binocular info representation

Question 34

binocular cells

Answer 34

respond when the corresponding spatial areas of the eye receptive fields are stimulated

Question 35

what does evidence indicate –> visual cortex

Answer 35

early visual experience can alter the development of binocularity cells