Visual System

Question 1

Why are eyes being fluid filled important?

Answer 1

the fluid helps bend the light and focus it on the posterior aspect of the eyeball

Question 2

Anatomy of the eyeball (pathway that light travels through)

Answer 2

Cornea (transparent first lens that allows light into your eye)

Pupil (behind the cornea, opening that lets light in)

Iris (surrounds the pupil, part of the eye that is colorful
, capable of expanding and contracting in response to the amount of the light in our environment)

Aqueous Humor (fluid in between the lens and the pupil)

Lens (allows us to change our depth of focus to see clearly at various distances/depths)

Vitreous humor (fluid behind the lens)

Vitreous chamber (takes the light through the eye to be reflected onto the back of the eye)

Retina (transduces light energy into electrical signals)

Nerve fibers (leave from the retina to make up the optic nerve)

Optic nerve (brings visual info the brain)

Question 3

What is the blind spot?

Answer 3

area of the eye where there are no light sensitive cells because it is where the optic nerve begins

Question 4

What are the Macula and Fovea?

Answer 4

the center of our vision

where light reflects

have the most dense number of photoreceptors

Question 5

What does the retina do in response to light input?

Answer 5

becomes hyperpolarized

Question 6

What happens when the rods or cones absorb a photon

Answer 6

the cell undergoes a shape or conformational change which results in an electrical potential

Question 7

What is the visual space

Answer 7

external world that both retinas can transduce

amount of the real world that you are currently looking at and both of the retinas are currently transducing

Question 8

What is the visual field

Answer 8

portion of space seen by each retina

Question 9

What is the monocular field and which retinas can see it?

Answer 9

your peripheral vision

both retinas can see it, but only your right eye can see your right monocular field, and only your left eye can see your left monocular field

Question 10

What are bipolar cells responsible for

Answer 10

peripheral visual system integration

Question 11

What makes photoreceptors unique?

Answer 11

They are the only cell type that is directly responsive to light energy

Question 12

What type of cells are the only pathway out of the retina and the only cell class to produce action potentials?

Answer 12

retinal ganglion cells

Question 13

Photoreceptors and bipolar cells can only operate through what in their electrical potentials?

Answer 13

graded changes in their electrical potentials, with neurotransmitter release from these cells proportional to the change in each cell’s membrane potential

Question 14

Characteristics of Rods

Answer 14

high sensitivity to light

more plentiful quantity of photopigment

slow response rate to light

night vision = specialization

low visual acuity

saturate in day light

no role in color vision

not present in the fovea

more numerous in the retina

damage causes night blindness and loss of peripheral vision

Question 15

Characteristics of cones

Answer 15

low sensitivity to light

less plentiful quantity of photopigment

fast response rate to light

day vision = specialization

high visual acuity

saturate in bright light

trichromatic role in color vision

high presence in the fovea

less numerous in the retina

damage causes blindness and loss of color vision

Question 16

what relationship do rods and bipolar cells have and what is the significance?

Answer 16

Rods have a one-to-many relationship with bipolar cells, indicating that a single bipolar cell combines signals from many rods

Question 17

Are cones or rods responsible for the majority of the retinas output

Answer 17

Cones, even though they are present in far fewer numbers in the retina

Question 18

What relationship do cones have with bipolar cells

Answer 18

One-to-one

Question 19

in light transduction, is there neurotransmitter release at rest?

Answer 19

Yes, even at rest there is some degree of neurotransmitter release

This is called being tonic

Question 20

Objects in the right visual field are imaged where on the R and L eye?

Answer 20

temporal retina of the L eye and the nasal retina of the R eye

Question 21

Objects in the left visual field are imaged where on the R and L eye?

Answer 21

the temporal retina of the R eye and the nasal retina of the L eye

Question 22

Receptive field

Answer 22

what a cell or neuron responds to in the real world (not all the information that is possible, but just what the cell or neuron finds behaviorally important)

Question 23

In what order does light wavelengths move through the visual system?

Answer 23

Photoreceptors –> bipolar cells –> retinal ganglion

*decrease in abundance as you move through (photoreceptors are the most abundant, retinal ganglion cells are the least abundant)

Question 24

Do off-center bipolar cells produce an inhibitory or excitatory effect?

Answer 24

inhibitory

decreases its neurotransmitter release when light hits its center which results in decrease in firing of the retinal ganglion cell below it

Question 25

Do on-center bipolar cells produce an inhibitory or excitatory effect?

Answer 25

excitatory

when the center of the field absorbs light, that causes excitation of the on-center bipolar cell which increases neurotransmitter release and therefore an increased firing of the retinal ganglion cell

Question 26

What is the pathway of the optic pathway?

Answer 26

begins in the retina as axon ganglion cells –> leaves the eye at the optic disc –> becomes the optic nerve —> extends to the optic chiasm which is where optic nerves from both eyes cross –> nerve fibers are now called the optic tract –> ends in the lateral geniculate nucleus of the thalamus where information is then passed on to the primary visual cortex by travel of axons (called optic radiations)

Question 27

What are examples of optic nerve damage (causes)

Answer 27

trauma, tumors, stroke, glaucoma

Question 28

What does damage in the right optic nerve effect?

Answer 28

can’t see the right monocular space

Question 29

What does damage in the optic chiasm effect?

Answer 29

Can’t see either monocular space

Question 30

What does damage in the right optic tract effect?

Answer 30

can’t see the left visual field (both binocular and monocular spaces)

Question 31

What is retinotopy

Answer 31

organization of real-world visual space maintained throughout the visual system

Question 32

Dorsal streams (what happens when information is passed dorsally)

Answer 32

processing WHERE and MOVEMENT information

integration of sensory information via your visual system in order to make judgements about where the visual stimulus is coming from

Question 33

Ventral streams (what happens when information is passed ventrally)

Answer 33

processing WHAT information

helping to integrate multiple stimulus characteristics to determine what is the thing you are looking at

*important for facial recognition