Von Bartheld: Vision II

Question 1

What’s this?

gateway to the cortex

Answer 1

lateral geniculate nucleus

Question 2

What’s this?

involved in the pupillary light reflex (reflex control of pupil and lens)

Answer 2

pretectum

Question 3

What’s this?

involved in circadian rhythm

Answer 3

hypothalamus

Question 4

What’s this?

involved in visual reflexes: orients the movements of the head and eyes

Answer 4

superior colliculus

Question 5

4 CNS targets of retinal ganglion cells

Answer 5

lateral geniculate nucleus
pretectum
hypothalamus
superior colliculus

Question 6

What is the nucleus involved in parasympathetic control of pupil size?

Answer 6

Edinger Westphal nucleus

Question 7

5 steps in parasympathetic control of the pupil

Answer 7

1. retinal ganglion cells receive light
2. pretectum
3. edinger-westphal
4. ciliary ganglion
5. constricts pupil

Question 8

How do sympathetics reach the pupodilator muscle of the iris to cause dilation?

Answer 8

sympathetics from T1-3 synapse in the cervical ganglion then travel on internal carotids. some sympathetics hop on the long ciliary branch of V1 and travel to the orbit or pass through the ciliary ganglion and take the short ciliary nerve to the pupodilator muscle of the iris

Question 9

Information from the left visual field travels is received by the right temporal retina and the left nasal retina. This input travels via the (blank) optic tract.

Answer 9

right

Question 10

Does information from the right and left eye mix in the lateral geniculate nucleus?

Answer 10

No! Mixing of fibers does not occur until the level of the visual cortex

Question 11

Images of objects that fall on non-corresponding parts of the two retinas

Answer 11

binocular disparities

*basis of stereopsis

Question 12

Images with small disparities can still be fused - they are interpreted as differences in (blank).

Answer 12

depth

Question 13

How many pathways are there from the LGN to the visual cortex?

Answer 13

2
*fibers arching up represent info from superior retinal quadrants (inferior visual field)
fibers arching down represent info from the inferior retinal quadrants (superior visual field)

Question 14

The (blank) is greatly over-represented in the retinotopic projection to visual cortex

Answer 14

fovea

Question 15

The visual cortex has a (blank) representation with a huge area devoted to the (blank)

Answer 15

upside-down; fovea

Question 16

Are there multiple visual cortex areas, or just one?

Answer 16

multiple *for different aspects of vision

Question 17

Crossing of nasal RGC axons in the chiasm to project the right visual field to the (blank) side of the brain and the left visual field to the right side of the brain.

Answer 17

left

Question 18

The LGN projects axons to (blank) layers in the visual cortex

Answer 18

four

Question 19

Several circular RGC receptive fields combine to form elongated fields on individual neurons in cortex. Why is this important?

Answer 19

several on-center cells converge on a single cell in the visual cortex, which creates one simple receptive field

Question 20

3 types of detectors present in the visual cortex

Answer 20

slit, line, edge

Question 21

Neurons in the visual cortex respond to distinct stimulus orientations. What does this mean?

Answer 21

there are certain neurons that only respond to a line that is upright, or a line that is slightly angled *only respond to specific orientations of stimulus

Question 22

Different retinal ganglion cell types (ex: some for spatial acuity color and some for rapid motion) take distinct pathways via the (blank) to the visual cortex

Answer 22

LGN

Question 23

The visual cortex is organized into (blank). The right and left eye-inputs are still (blank) in the 4th layer of the cortex (they go to different cortical columns)

Answer 23

columns; segregated

Question 24

Large visual defects are called (blank), while smaller visual field deficits are called (blank)

Answer 24

anopsias; scotomas

Question 25

What is bilateral (heteronomous) hemianopsia?

Answer 25

loss of 1/2 of visual field on opposite sides in the two eyes

Question 26

What is left homonomous hemianopsia?

Answer 26

loss of 1/2 of visual field on the same side in both eyes

Question 27

What is left superior quadrantanopsia?

Answer 27

loss of left superior visual field

Question 28

What is left homonomous hemianopsia with macular sparing?

Answer 28

loss of same 1/2 visual field on both sides, but sparing the macula (circle in center)

Question 29

What would a maculopathy cause?

Answer 29

a dot in the center of your vision

*this is a scotoma (small visual deficit)

Question 30

What would retinitis pigmentosa look like?

Answer 30

black around the periphery, like a filter

*this is a scotoma (small visual deficit)

Question 31

How can you get loss of vision in one eye?

Answer 31

lesion anterior to the optic hchiasm

*eye, retina, optic nerve

Question 32

What does a pale optic disc suggest?

Answer 32

a lesion in the optic nerve