Visual System

Question 1

What are retinofugal projections?

Answer 1

Axons that leave the retina of the eye

Question 2

What is the main target of retinofugal projections?

Answer 2

LGN of thalamus–up to 20% of optic nerve/tract axons have other brain targets

Question 3

Are Nasal hemitetinal fibers decussating or non decussating

Answer 3

decussating

Question 4

Are Temporal hemiretina fibers decussating or non decussating

Answer 4

non-decussating

Question 5

What is the inner limits of our vision based on

Answer 5

our noses

Question 6

_____ zone (field) is area seen by both eyes

Answer 6

binocular

Question 7

_____ zone (field) is area seen by just one eye

Answer 7

monocular

Question 8

Right visiaul field represented by ____ visual cortex

Answer 8

left

Question 9

The right visiual field falls on the temporal hemiretina of the ____ eye and is registered in that visual cortex

Answer 9

left

Question 10

The right visual field falls on the nasal hemiretina of the right eye and is registered in the ____ visual cortex

Answer 10

left

Question 11

Left side of the brain sees the ____ half of the world

Answer 11

right

Question 12

horses have a (larger/smaller) binocular vision zone

Answer 12

smaller due to their elongated noses

Question 13

What is the function of the main retinofugal projects that go from the retina to the LGN of thalamus?

Answer 13

conscious vision, movement, and object recognition, etc.

Question 14

Layers 3-6 are responsible for seeing what

Answer 14

colors and detail

Question 15

Layers 1 and 2 of the LGN are responsible for seeing what

Answer 15

patterns and motion

Question 16

T/F visual information from each eye is kept separate in the LGN

Answer 16

True

Question 17

LGN we have visual information from both eyes, but they aren’t really mixing–there is no _______ vision yet

Answer 17

Binocular

Question 18

What layers of the LGN are contralateral inputs

Answer 18

1
4
6

Question 19

What layers of the LGN are ipsilateral inputs

Answer 19

2
3
5

Question 20

Right LGN sees the ____ side of the world

Answer 20

left

Question 21

Left LGN sees the ____ side of the world

Answer 21

right

Question 22

From the LGN where do the retinofugal fibers go?

Answer 22

V1

Question 23

What are the 3 subcortical targets of the optic tract

Answer 23

-pre Tectum
-superior colliculus
-Suprachiasmatic nucleus of the hypothalamus

Question 24

What does the pretectum control

Answer 24

pupillary light reflex

Question 25

What does the superior colliculus control

Answer 25

gaze shifting/eye movements

Question 26

What does the Suprachiasmatic nucleus of the the hypothalamus control

Answer 26

circadian rhythms

Question 27

Would a lesion of the LGN, optic radiation or visual cortex have any effect on the projections of the subcortical targets

Answer 27

NO, these fibers split from the optic tract prior to the Thalamus

Question 28

What does the pupillary reflex allow the eye to do?

Answer 28

Adjust amount of light reaching retina protect photoreceptors from bright light

Question 29

_________ of the midbrain mediates the pupillary light reflex

Answer 29

Pre tectum

Question 30

To keep vision consisten, what must occur during the pupillary light reflex?

Answer 30

consensual changes to pupil

Question 31

Do some optic tract axons not synapse in LGN, but pass by to synapse in pretectum of midbrain

Answer 31

YES

Question 32

Pretectum neurons synapse bilaterally onto _______ nucleus

Answer 32

edinger westphal

Question 33

From the Edinger-Westphal nucleus where are upper motor neurons sent

Answer 33

to the ciliary ganglion outside the eye as part of CN lll

Question 34

What do the cilliary ganglion lower motor neurons tell the muscles in the pupil to do with pupillary light reflex

Answer 34

constrict

Question 35

T/F many muscles controlling the eyes are under voluntary control but often do not require conscious though, are somewhat automated

Answer 35

True

Question 36

What do conjugate movements involve

Answer 36

activating opposite muscles of L and R eyes to movement towards same point in space

Question 37

What do vergence movements move

Answer 37

central axis of each eye towards (convergence) or away from each other (divergence)

Question 38

Where is the suprachiasmatic nucleus SCN

Answer 38

in hypothalamus

Question 39

What does the SCN generate

Answer 39

24h circadian rhythms for the body via hormones and neurotransmitters

Question 40

What does our circadian rhythm require

Answer 40

light

Question 41

What visual functions only need to detect the presence of light

Answer 41

pupillary light response photosensitivity for setting circadian rhythms

Question 42

T/F rats with genetic pathologies that lack rods and cones still show circadian rhythm...but removing the eye disrupts circadian function

Answer 42

true

Question 43

Do photo-sensitive retinal ganglion cells require inputs from receptors

Answer 43

not always

Question 44

SCN gets input from the

Answer 44

intrinsically photo-sensitive retinal ganglion cells

Question 45

How are intrinsically photo-sensitive RGCs distributed

Answer 45

evenly over the retina

Question 46

Where do the intrinsically photo-sensitive retinal ganglion cells exit at

Answer 46

optic nerve head with other RGC axons to make up the optic nerve

Question 47

Where do you peel away optic nerve to target hypothalamus

Answer 47

peel away from optic nerve around the point of chiasm (decussation)