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Perception 351 > Chapter 2 > Flashcards

Chapter 2 Flashcards

1
Q

light

A

the spectrum of electromagnetic radiation that can be detected by a visual system

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2
Q

light can be conceptualized as a ______ (when moving around the world) or as a stream of _____ (when absorbed)

A

wave; photon

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3
Q

photons

A

quantum of electromagnetic radiation that has both particle and wave like properties

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4
Q

light obeys properties of _____ made up of ______

A

waves; photons

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5
Q

our visible portion is _____ when compared to the electromagnetic spectrum

A

tiny

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6
Q

absorbed

A

light is taken up and is not transmitted further

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7
Q

scattered

A

light is dispersed in an irregular/random fashion

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8
Q

how does scattered light gives the sky its color?

A

blue during the day as the sun is direct and not a lot of blue light is scattered

reddish orange at dawn/dusk as the sun is not direct and therefore scatters more

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9
Q

reflected

A

light is redirected, generally back the way it came

ex) mirror or lake on a calm day

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10
Q

transmitted

A

light is passed through a surface (without being reflected or absorbed)

ex) light through a glass window

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11
Q

refracted

A

light is altered as it passes through a medium

ex) light through the eye!

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12
Q

white light is made up of

A

all colors

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13
Q

cornea

A

the transparent “window” to the eye

first part of eye light hits

no blood vessels = clear

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14
Q

pupil

A

hole in musculature/iris that lets light through into the eye

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15
Q

iris

A

colored portion of the eye

muscular diaphragm surrounding the pupil that controls the amount of light by dilating or contracting

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16
Q

lens

A

curved structure that bends/focuses light onto the back of the eye

crystalline but also flexible

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17
Q

aqueous humor

A

fluid between the cornea and the lens

provides oxygen and nutrients to the cornea and lens while also removing waste

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18
Q

vitreous chamber/humor

A

the large open space of the eye is the chamber, filled with humor

80% of the eye

gel-like fluid that helps maintain eye shape

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19
Q

retina

A

light sensitive membrane at the back of the eye where photoreceptors are, which transduce light to electrochemical signals

where seeing begins

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20
Q

optic disc

A

the point on the eye where the optic nerve exits the eye

blind spot as it has no photoreceptors!

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21
Q

layers of the eye

A

sclera
- outer layer of the eye/the “white” of the eye
- supportive of vision

choroid
- middle layer filled with blood vessels to supply oxygen and nutrients to the retina
- supportive of vision

retina
- inner layer where photoreceptors are found
- contributed to vision

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22
Q

fundus

A

back part of the eye made up of:

retina
macula and fovea
optic disc

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23
Q

the path of light

A

1) cornea
2) pupil
3) lens
- image is flipped at this point
4) retina/macula/fovea
- here transduction occurs

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24
Q

the lens uses _______ to focus light onto the retina

A

refraction

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25
Q

the lens can be adjusted by the ______ _______ to alter is refractive power in a process called __________

A

ciliary muscle; accommodation

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26
Q

presbyopia

A

“old sight”

the age-related loss of accommodation, which makes it hard to focus on near objects

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27
Q

how the ciliary muscle works for close and far sight

A

for distance objects, the muscle relaxes making the zonules tighten and lens become thin

for near objects, the muscles contracts, zonules loosen and lens becomes thicker

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28
Q

emmetropia

A

eye correctly refracts light onto the retina

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29
Q

myopia

A

nearsightedness

light is focused in front of the retina and distant objects cannot be seen sharply

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30
Q

shape of eye with myopia

A

elongated eye

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31
Q

hyperopia

A

farsightedness

light is focused behind the retina and near objects cannot be seen sharply

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32
Q

shape of eye with hyperopia

A

shortened eye

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33
Q

astigmatism

A

unequal curving of one or more of the refractive surfaces of the eye, usually the cornea

resulting in multiple focal points on the retina instead of just one

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34
Q

spot in the eye with the highest concentration/densest of photoreceptors and highest acuity

A

fovea

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35
Q

acuity

A

sharpest detail

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36
Q

rods

A

specialized for night vision

respond well in low luminance conditions

do not process color

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37
Q

cones

A

specialized for color vision and acuity

respond well in daytime conditions

can remember C for Color

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38
Q

once transduced, neural signal travels back up from (1), to (2), to (3), to (4)

A

rods/cones
bipolar cells
ganglion cells
optic nerve

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39
Q

what shape does the fovea appear as and why?

A

divot, upper layers bend away from focal point which means fewer layers to travel through and a higher density of cones

40
Q

where are cones and rods most present?

A

cones: fovea
rods: peripheral vision

41
Q

the visual angle of an object is a function of both its _________ and _____ from the observer

A

actual size; distance

42
Q

the fovea has ____ acuity while the periphery has _____ acuity

A

high; low

43
Q

macular degreneration

A

a disease associated with aging that affects the macula/fovea and gradually destroys sharp central vision

causes central vision loss, resulting in a blind spot in the visual field called a scotoma

44
Q

the fovea has ____ light sensitivity while the periphery has ____ light sensitivity

A

low; high

45
Q

4 mechanisms for dark and light adaption

A

pupil dilation

photoreceptors and their replacement

duplex retina - rods/cones

neural circuitry beyond rods/cones

46
Q

pupil dilation

A

the pupils size changes to adjust how much light is being let in

only a small part of light adaption, slow and only does so much

47
Q

range of brightness

A

scotopic

cone threshold between
- no color vision and poor acuity

mesopic

rod saturation begins
- good color vision and best acuity

photopic

48
Q

photopigments

A

class of proteins in rods and cones that absorb light and trigger a biochemical cascade that alters the electrical properties of the photoreceptors

finite in the moment but replenished over time

49
Q

bleached

A

when photopigments are used, can’t detect light until replenished

50
Q

when there are few photons available, we _________________. When there is a ton of light, we _________________

A

have lots of photoreceptors to process whats there; only process part and ignore the rest

51
Q

cones replenish ______ and are _____ sensitive in the dark when compared to rods

A

faster; less

52
Q

rods replenish ______ and are ______ sensitive in the dark when compared to cones

A

slower; more

53
Q

why did pirates wear eye-patches?

A

to have a dark adapted eye for below deck!

54
Q

if we were to rank portions of the retina from worst to best acuity, what relationship would be correct?

a) periphery is worse than fovea and macula. Fovea and macula are equal
b) periphery is worse than macula which is worse than fovea
c) periphery is worse than fovea which is worse than. the macula
d) periphery is similar to the macula, and both are worse than the fovea

A

b) periphery is worse than macula which is worse than fovea

55
Q

structural/support features of the eye

A

sclera
choroid
aqueous humor
vitreous chamber/humor

56
Q

what controls the lens shape?

A

ciliary muscle, connected to lens by the Zonules of Zinn (white strings)

57
Q

passing on light parts of the eye

A

cornea
pupil
lens

58
Q

transduction parts of the eye

A

retina
macula and fovea
optic disc
optic nerve

59
Q

what does the inner segment of rods/cones do? outer segment?

A

inner - produces photopigments
outer - stores photopigments for transduction

60
Q

photopigments contain opsins, which

A

determine the wavelength of light the photoreceptor responds to

61
Q

action potentials are driven by __________ of the cell, allowing for _____________

A

depolarization; longer range communication

62
Q

graded potentials

A

measuring amount of depolarization/hyperpolarization

found in photoreceptors and

63
Q

the more depolarized the cell is, the _____ neurotransmitter it releases

A

more

64
Q

photoreceptors release a neurotransmitter called

A

glutamate

65
Q

when light is present, the photoreceptor is always _______

A

hyperpolarized

66
Q

when the photoreceptor is hyperpolarized, there will be ____ glutamate released to the bipolar cells

A

less

67
Q

bipolar cells

A

intermediary cell between photoreceptors and ganglion cells

graded potentials

divided by:
convergence/divergence
off/on

68
Q

diffuse bipolar cell

A

periphery, receives input from many photoreceptors (usually rods)

high convergence (many photoreceptors are converging on a singular bipolar cell)

high: sensitivity and convergence
low: acuity

69
Q

midget bipolar cell

A

fovea, receives input from a single cone and passes it on to a single ganglion

divergence/low convergence, 1:1 ratio

high: acuity
low: sensitivity and convergence

70
Q

off bipolar cells

A

deactivate in the presence of light

receptors are excited by glutamate

photoreceptors are depolarized

more active in the dark

71
Q

on bipolar cells

A

active in the presence of light

receptors are inhibited by glutamate

photoreceptors are hyperpolarized

more active in light

72
Q

in on cells, light on –> (less/more) glutamate —> (depolarized/hyperpolarized) cell

A

less; hyperpolarized

73
Q

when a photoreceptor is exposed to light, becomes hyperpolarized, and releases less glutamate to an ON bipolar cell, the bipolar cell becomes depolarized due to …

A

release from inhibition

on cells are inhibited by glutamate so if there is less glutamate they are released from their inhibition, allowing the cell to act

74
Q

if a cone is in the dark, the photoreceptor is depolarized and releases more glutamate, which bipolar cell will release a signal?

A

off bipolar cell

75
Q

if a cone is in the light, the photoreceptor is hyperpolarized and releases less glutamate, which bipolar cell will release a signal?

A

on bipolar cell

76
Q

ganglion cells

A

final layer of the retina

uses action potential

primary divisions:
P vs. M cells
on-center vs. off-center

77
Q

3 ways P and M ganglion cells differ

A

1) by the region of the brain they send their signal
2) by their size
3) by the type of bipolar providing input

78
Q

M ganglion cells

A

large in size as they receive input from diffuse bipolar cells (same convergence (+), sensitivity (+) and acuity (-))

M means Massive

79
Q

P ganglion cells

A

small in size as they receive input from midget bipolar cells (same convergence (-), sensitivity (-), and acuity (+))

P means Petite

makes up most ganglion cells as you need more since they are 1:1 ratio with bipolar cells

80
Q

each layer of neural communication in the eyes through cones

A

photoreceptors, midget bipolar cells, P ganglion cells, small receptive fields (fovea)

81
Q

each layer of neural communication in the eyes through rods

A

photoreceptors, diffuse bipolar cells, M ganglion cells, large receptive fields (periphery)

82
Q

receptive fields

A

influence space that can influence a neuron

83
Q

larger receptive fields = ___ acuity

A

lower

84
Q

ganglion receptive fields are particularly coded to detect differences in the intensity of light, hence the need for …

A

“center-surround” receptive field

85
Q

center-surround focuses on

A

contrast (differences between luminance of adjacent regions)

86
Q

horizontal cells

A

part of lateral connection between photoreceptor cells + bipolar cells

allows the surround photoreceptors to inhibit whatever information it was getting from center (center-surrond)

87
Q

on-center for lateral inhibition

A

if the light is hitting the center, the surround fails to inhibit it = light is perceived

if the light is hitting the surround, the center will be inhibited = light will not be perceive

88
Q

off-center for lateral inhibition

A

if the light is hitting the center, the surround fails to inhibit it = light will not be perceived

if the light is hitting the surround, the center will be inhibited = light will be perceived

89
Q

lateral inhibition

A

adjacent cells at the same level blocking/inhibiting each other’s effects

emphasizes priority of contrasts

90
Q

explain why we can see dots in between black boxes

A

both eyes open:
- can see the dot when looking directly at the cross point and in your periphery b/c the periphery has larger receptive fields. the center is saying on but the surround are also being hit, causing lateral inhibition and perceived dots to appear

one eye open:
- receptive field shrinks causing you to not see dots directly at the cross section but still in your periphery

91
Q

amacrine cells

A

horizontal connection between bipolar and ganglion cells

92
Q

Which cells are responsible for lateral inhibition in the retina?

A

horizontal cells

93
Q

when light hits a photoreceptor, it _________ and releases _____ glutamate

A

hyperpolarizes; less

94
Q

which of the following is NOT an example of convergence?

1) multiple photoreceptors feeding input to a single bipolar cell
2) multiple bipolar cells feeding input to a single ganglion cell
3) multiple bipolar cells receiving input from a single photoreceptor
4) All are examples of convergence

A

3) convergence needs to be going from a single source to multiple

95
Q

which of the following are not characteristics of cells in the fovea?

1) Show generally low convergence
2) Have relatively small receptive fields
3) have generally smaller bipolar and ganglion cells
4) all of the above are characteristic of foveal cells

A

4)

Perception 351 (21 decks)

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