9. Neuro-optho

Question 1

ON-center system: Light is shined in the middle with darkness in the surround

Answer 1

Higher rate of firing

Question 2

ON-center system: Light is shined in the surround with darkness in the middle

Answer 2

Low rate of firing

Question 3

ON-center system: Darkness in the surround and center

Answer 3

Medium rate of firing

Question 4

ON-center system: Light in the surround and center

Answer 4

Medium rate of firing

Question 5

OFF-center system: Light is shined in the middle with darkness in the surround

Answer 5

Low rate of firing

Question 6

OFF-center system: Light is shined in the surround with darkness in the middle

Answer 6

High rate of firing

Question 7

OFF-center system: Darkness in the surround and center

Answer 7

Medium rate of firing

Question 8

OFF-center system: Light in the surround and center

Answer 8

Medium rate of firing

Question 9

FACT: Major changes in firing rates of the ON and OFF center occur in the edges

Answer 9

FACT: Major changes in firing rates of the ON and OFF center occur in the edges

Question 10

Scotopic vision

Answer 10

Allows you to see in starlight

Question 11

Photopic vision

Answer 11

Allows you to see in bright light

Question 12

Mesopic vision

Answer 12

Allows you to see in dim light (moonlight) (combo scotopic and photopic)

Question 13

Which adaptation process takes longer: dark adaptation or light adaptation?

Answer 13

Dark adaptation takes longer (20-30mins) because you need to replenish all photopigments

Question 14

Visual pathway

Answer 14

Optic nerve –> optic chiasm –> optic tract –> synapses with: 1. Lateral geniculate nucleus –> optic radiations or Meyer’s loop –> primary visual cortex 2. Suprachiasmatic nucleus –> wakefullness/sleep (circadian rhythm) 3. Superior colliculus –> coordinated eye movements 4. E-W nucleus –> pupillary reflex

Question 15

A right side up person appears how in the retina?

Answer 15

Upside down and flipped right-to-left

Question 16

Importance of visual information to cross over at center

Answer 16

Allows for depth perception

Question 17

Which region of the retina accounts for a disproportionate cross-sectional area of the optic nerve, tract, radiations, and cortex?

Answer 17

Foveal region

Question 18

What is the Meyer’s loop? What specific information does it carry?

Answer 18

Meyer’s loop is optic radiation fibers that curve anteriorly first before going posteriorly. Carry lower retinal fibers that carry upper visual field information

Question 19

What happens if you have a lesion in the RIGHT Meyer’s loop?

Answer 19

Can’t see left upper visual field (left quadrant)

Question 20

Scotoma

Answer 20

Partial alteration in field of vision

Question 21

Where would this lesion be?

Answer 21

Homonomyous hemianopia

Left optic tract (contralateral homonomyous hemianopia)

Question 22

Where would this lesion be?

Answer 22

Bitemporal hemianopia

Optic chiasm

Question 23

Answer 23

Heteronymous hemianopia

Question 24

Where would this lesion be?

Answer 24

Right Meyer’s loop