Visual

Question 1

What are the 3 cellular layers of the retina, in order that light goes through first.

Answer 1

• Ganglion cell layer
• Bipolar cell/interneuron layer
• Photoreceptors

Question 2

Axons of what cells form the optic n.?

Answer 2

Ganglion cells (first AP)

Question 3

Rods vs. cones-

Which has more photopigment per cell?

Answer 3

Rods (larger/taller)

Question 4

Rods vs. cones-

Which has higher temporal resolution/faster response/shorter integration time?

Answer 4

Cones (less convergence in pw)

Question 5

Rods vs. cones-

Which are saturated in daylight?

Answer 5

Rods

Question 6

Rods vs. cones-

Which has more convergence on retinal pw’s?

Answer 6

Rods

Question 7

Where in the retina is our best visual acuity?

Answer 7

Fovea (cones only)

Question 8

Explain the entire visual pw from photoreceptor to cortex.

Answer 8

1. Photoreceptor stimulates ganglion cell to send first AP.
2. AP reaches optic n.
3. Nasal portion of retinal nn. cross at optic chiasm, temporal portions do not. Optic tract is formed.
4. Optic tract synapses at LGN of thalamus
5. Optic radiations reach visual cortex

Question 9

Rods vs. cones-

M-type ganglion cells are associated w/_____, P-type cells are associated w/_____.

Answer 9

Mr. PC

• Rods (respond best to Movement)
• Cones (respond best to color and fine details)

Question 10

What is the Brodmann’s area # for the primary visual cortex?

What’s another name for it?

Answer 10

#17
- Striate cortex

Question 11

Where are visual reflexes processed in the brainstem (not the cortex)?

Answer 11

*Pretectal area

Question 12

Where are head and eye movements processed in the brainstem (not the cortex)?
[E.g. orienting reflex when something wiggles in our peripheral vision.]

Answer 12

*Superior colliculus

Question 13

Regarding optic radiations, upper fibers run thru the _______________, lower fibers run thru the _______________.

Answer 13

• Parietal lobe

- Temporal lobe

Question 14

How do lower fibers (of optic radiations) reach their path in the cortex?

Answer 14

Meyer’s loop

Question 15

What physical/anatomical landmark runs deep to divide the occipital lobe at Brodmann’s area #17?

Answer 15

Calcarine fissure

Question 16

What is the result of cutting the right optic n.?

Answer 16

Right eye blindness

Question 17

Cutting the center of the optic chiasm only would lead to what?

Answer 17

Bitemporal hemianopia–loss of R field of R eye and L field of L eye
(besides cutting optic n., this is only result that effects both eyes differently)

Question 18

What is the result of cutting the right optic tract or lesioning the right LGN?

Answer 18

Left homonymous hemianopia–loss of left field of both eyes

Question 19

Right temporal lobe lesion would lead to what result?

Answer 19

“Pie in the sky” Left homonymous upper quadrantanopia–loss of pie slice on upper left of both eyes

Question 20

Cutting of the right optic radiation would lead to what result?

Answer 20

Left homonymous lower quadrantanopia and macular sparing is often present–loss of most of left field of both eyes, sometimes center is spared

Question 21

Lesion of the right visual cortex would lead to what result?

Answer 21

Left homonymous hemianopia with macular (fovea) sparing–loss of entire left field of both eyes w/center spared

Question 22

After a deceleration injury, what is a common visual effect?

Answer 22

Loss of center of field only

Question 23

What’s the name of the test that tests the optic n.?
What are the names of the 2 subtype reflexes?
What are we testing to confirm functionality?

Answer 23

• Pupillary light reflex
• If you shine a light in 1 eye, the response of the illuminated eye is the direct reflex, the response of the unilluminated eye is the consensual response.
• Testing both eyes confirms rostral midbrain is functional

Question 24

What is the nucleus associated with the pupillary light reflex?
How come the reflex effects both eyes?

Answer 24

• Edinger-Westphal nucleus (EWN)

- Single optic n. splits at chiasm to supply both EWN’s.

Question 25

After leaving the EWN, what efferent CN goes on to perform the pupillary light reflex? What nucleus does this CN synapse at before reaching the eye, and what major (brainstem) area does this CN travel thru before reaching said nucleus?

Answer 25

- CN III - Ciliary ganglion (bilaterally) - Sup colliculus

Question 26

After R optic n. dmg, describe the pupil size of each. | How would each pupil respond to light when light is shown in each eye?

Answer 26

- Both have normal pupil size | - Neither responds to light shown into R eye. Both constrict w/light to L eye.

Question 27

After R oculomotor n. dmg, describe the relative pupil size of each eye. How would each pupil respond to light?

Answer 27

- R pupil is dilated, L is normal | - R eye doesn't respond to light shown in either eye (L eye should respond to light shown in either eye)

Question 28

What causes Horner's syndrome and what are the sx, + is it contralateral or ipsilateral?

Answer 28

- Loss of sympathetic output to the head - Ptosis (of eyelid), miosis (constricted pupil), anhydrosis (loss of sweating) - Ipsilateral to lesion

Question 29

If someone had a lesion to CN III, what direction would their eye appear to be looking?

Answer 29

Down and out

Question 30

What is the purpose of the accommodation reflex? | What eye movements does it entail?

Answer 30

Changing gaze to focus on nearby object. - Vergence of eyes, ciliary m. constriction (lens thickens), constriction of both pupils (conscious act, so involves cerebral cortex)

Question 31

What initiates the corneal eye blink reflex? | What is the pathway? (think hard)

Answer 31

- Free nerve endings in the cornea (among anything else that might make you blink) - Cornea > CN V > Chief sensory nuc of V > interneurons (reticular formation) > Motor nuc of VII > CN VII > obicularis oculi (blinks)

Question 32

What is the greatest numerical layer in the visual cortex and what does it do?

Answer 32

Layer IV, processes input (there's lots of input)

Question 33

What are the 3 main specialized "hypercolumns" of the visual cortex?

Answer 33

1. Orientation (edges) 2. Blobs (color) 3. Ocular dominance (L vs. R)

Question 34

"Where" an object is is determined in the _______________, "what" an object is is determined in the _______________.

Answer 34

- Parietal lobe | - Temporal lobe

Question 35

What are the 2 basic ways to detect motion of an object?

Answer 35

1. Temporal association: image moves temporally across retina while eye remains stationary 2. Head and eyes move to fix image on the fovea - Both indicate that the object must be moving

Question 36

What colors are part of the eye's cone system? | How many different photoreceptor types do we need to perceive color?

Answer 36

- Red, green, blue (wavelength ranges overlap) | - 2