Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

PSYC 2220 > Light & The Eye > Flashcards

Light & The Eye Flashcards

1
Q

What is light made up of?

A

photons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How does light behave?

A

sometimes like a wave other times like a particle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What is wavelength?

A

distance from peak to peak or crest to crest of waves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the effects of different wavelengths on photons?

A

gives photons different energy levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the wavelengths of visible light?

A

400-700nm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is a nanometer?

A

represented by nm, 1/billionth of a meter or 10^-9

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What colour has the highest wavelength? What does this mean for its energy level?

A

red, lowest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What colour has the lowest wavelength? What does this mean for its energy level?

A

blue/purple, highest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What wavelengths make up the majority of the solar spectrum?

A

visible light (400-700)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Explain why the sky is blue?

A

shorter wavelengths are scattered more when they enter a transparent material like the atmosphere, therefore we see blue since it has the shortest wavelength

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Explain why sunsets/sunrise look red?

A

because of where the sun is positioned light needs to pass through more atmosphere to reach our eyes, therefore blue light is scattered more so only red/orange is left over

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Do all animals have the same light sensitivity spectrum?

A

no

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What 3 things can cause photons to not travel in a straight line?

A

reflection, refraction, absorption

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is reflection? Example?

A

light bouncing off something and returning back to the medium it came from

mirror

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is refraction? Example?

A

light travels from one transparent medium to another and it bends/changes direction

distortion from something being udnerwater

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is absorption? Example?

A

when photon disappears and the energy is transferred to something else

light is absorbed and releases heat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What do photons consist of?

A

One quantum of energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Order all categories on electromagnetic spectrum from shortest wavelength to longest?

A

Gamma rays, x rays, ultraviolet, visible light, infrared, heat, microwaves, radio, television

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is the first thing light passes through when it enters the eye?

A

Cornea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is the cornea?

A

Transparent, at front of eye, let’s light through, has no blood vessels but has transparent sensory nerve ending

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Why is it important that the cornea have sensory nerve endings?

A

Force eyes to close and produce tears of cornea is scratched

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the purpose of tears?

A

Tears reduce risk of eye infection, tear film lubes eyes, provides smooth clear surface, helps protect eyes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How does cornea get oxygen and nutrients?

A

Aqueous humor, also supplies lens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Where is the aqueous humor located? What is its consistency?

A

Between cornea and lens,

liquid, water like

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the pupil?

A

Hole in center of iris, let’s light through, size changes via iris

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the iris?

A

Colour part of eye, ring like muscle, controls pupil size

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is the lens also called?

A

Crystalline lens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the purpose of the lens?

A

Helps focus light on retina, more fine tuning than cornea, changes shape to change focusing power

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

How many times is light refracted before it hits retina? What does this?

A

4 times

Cornea, aqueous humor, lens, vitreous humor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the longest part through journey of eye by light?

A

Passing through vitreous chamber that is filled with vitreous humor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Where is the vitreous humor located? What is its consistency?

A

Between lens and retina

Gel like, viscous, think egg white

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What are floaters? What causes them?

A

When looking at sky might have noticed translucent shapes floating around in eye

Biodebris floating in vitreous humor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How much of the light that arrives at the cornea reach the retina?

A

50%

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Lens power is equal to what?

A

=1/f

f is focal distance in meters

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What are cataracts?

A

Opacity of the lens, can occur at many ages and take different forms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What are zonules of zinn?

A

connect ciliary muslce to lens, when muscle relaxes it pulls on lens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What layer of the retina does light reach last?

A

photoreceptor layer

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is presbyopia?

A

age related loss of accomadation, makes it hard to focus on near objects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What are bifocals?

A

correction for your distance vision on the top of the lens, and a correction to help you read on the bottom

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is emmetropia?

A

no refractive error because length of eyeball is perfectly matched with refractive power of lens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

How can myopia be corrected?

A

w/negative (-) lenses, they diverge the light rays, they are concave shaped

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

How can hyperopia be corrected?

A

w/positive (+) lenses, they converge light rays, they are convex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What is the most powerful refractive surface in eye?

A

cornea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What is astigmatism?

A

unequal curving of one/more of refractive surface in eye, usually cornea

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

Each retina contains how many photoreceptors?

A

100 million

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

What type of neuron does not spike?

A

photoreceptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Do humans have more rods or cones?

A

rods

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Why do humans have duplex retinas?

A

because we have rods and cones and they operate at different capaciteies

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

Describe the photoreceptor density grpah?

A

rods start about mid way and they sloley rise til they get to the fovea and drop to 0, its mirrored on the other side, cones are very low and then quickly increase at fovea, cuts off at optic disc and cotniunues after it

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

How can you estimate what 1 visual angle looks like?

A

index finger held up at arms length is 1 visual degree, thumb is 2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

If we look at an image that is less thean 1 visual degree where will the image land?

A

region with only cones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What lighting do rods function best it?

A

scotopic (dim light)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

What lighting do cones function best in?

A

photopic (bright light)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Why can cones detect colour but not rods?

A

cones can have three different types of photopigments, rods all have same one

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Where do rods and cones get energy?

A

retinal pigment epithelium which lies below the retina

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Why do your eyes adjust after staying in dark for a bit?

A

the threshold decreases (means sensitivity increases)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What is mesopic vision?

A

between photopic and scotopic, rods and cones contribute

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What are the four ways out visual system adjusts for luminence?

A

pupil size, photopigment regeneration, dpulex retina, neural circuity

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

How much does pupil size vary?

A

2mm to 8mm

59
Q

How much more quanta can enter the eye when dilated?

A

16x

60
Q

How does photopigment regernation affefct out ability to detect luminence?

A

in dim lighting there is a lot of leftover photopigments but in bright some light is not used b/c no photopigmnet to absorb it, gives up wide range of sensititity

61
Q

How do our duplex retina allow us a wide sensitivity range?

A

rods detect dim light, only 1 photon needed as they get saturated cones start to take over, once light dims again and the rods recover we can see in dim lighting again

62
Q

What are the 5 major classes of neurons in the retina?

A

photoreceptors, horizontal cells, bipolar cells, amacrine cells, ganglion cells

63
Q

Where are visual pigments made in photoreceptors? Where are they stored?

A

inner segment

outer segment

64
Q

Each visual pigment molecule is made up of what?

A

protein (opsin) and a chromophore (retinal)

65
Q

What does chromophores do?

A

captures light photons

66
Q

What is the chromophore, retinal, derived from?

A

vitamin A

67
Q

Where is rhodopsin found?

A

only in rods

68
Q

What is melanopsin?

A

photopigment that is senstive to ambient light

69
Q

What photoreceptor cells contain melanopsin?

A

melanopsin-containing retinal ganglion cells/intrinsically photosensitive retinal ganglion cells

70
Q

What might influence pupil response?

A

melanopsin

71
Q

What is bleaching?

A

photoactivation, photon is absorbed by photoreceptor and activatews it

72
Q

What does photoactivation eventually result in?

A

closing of cell membrane channels that normally allow ions to flow into rods outer segment, makes inside more (-)

73
Q

What is the amount of glutamate present in the photoreceptor/bipolar cell synapse is proportional to what?

A

inversly proportional to number of photons being absorbed by photoreceptor

74
Q

How do photoreceptors respond? (actiona potential or graded)

A

graded potentials

75
Q

Are the 3 photopigments in cones distributed equally?

A

no

76
Q

What photopigments are least prevalent in cones? Where are they not found?

A

short wavelength sensitive

fovea

77
Q

What are the most prevalent cone photopigments?

A

long wavelength sensitive

78
Q

What are horizontal cells?

A

run perpendicular to photoreceptors and make cotnact with photoreceptors and bipolar cells

79
Q

What plays an important role in lateral inhibition?

A

horizontal and amacrine cells

80
Q

What is lateral inhibition?

A

when an excited cell reduces the activity of neighbouring neurons

81
Q

What are amacrine cells?

A

cells in inner nuclear layer that makes synaptic connections with bipolar cells, ganglion cells, and other amacrine cells

82
Q

What have amacrine cells implicated with?

A

contrast enhancement and temporal sensitivity (not sure of exact function tho)

83
Q

What cells form a lateral pathway in retina? What about vertical?

A

horizontal and amacrine

photoreceptors, bipolar, ganglion

84
Q

What are bipolar cells?

A

make synapses with either rods or cones and horizontal cells and then passes signal to ganglion

85
Q

What is the difference btwn midget and diffuse bipolar cells?

A

diffuse gets input from many cones and midget gets input from 1

86
Q

What is ON bipolar cell vs OFF bipolar cell?

A

the two bipolar cells contacted by a foveal cone, the one that depolarizes is ON cell, the other that hyperpolarizes if OFF cell

87
Q

Midget bipolar cells send their signal to what ganglion cell?

A

p ganglion cells, called this because it projects to parvocellular layer of LGN

88
Q

Diffuse bipolar cells send their signal to what ganglion cells?

A

m ganglion cells, called this beacuse projects to magnocellular layer of LGN

89
Q

Are there more P or M ganglion cells?

A

more P

90
Q

What do receptive fields of ganglion cells look like?

A

circularish (center surround)

91
Q

What are the two types of center surround fields?

A

ON center and OFF center

92
Q

How do retinal ganglion cells act as a filter?

A

will respond best to spots of certain sizes

93
Q

What are ganglion cells the most sensitive to?

A

differences in intesnity of light in center/surround (contrast)

94
Q

Do P gnagliion cells or M ganglion cells have bigger recpetive fields?

A

P cells have a smaller receptive field

95
Q

Are M cells or P cells more sensitive?

A

M cells are more sensitive

96
Q

Do P cells or M cells have better visual acuity?

A

P cells

97
Q

How do P cells react to sustained light on center?

A

sustained firing for entire duration

98
Q

How do M cells react to sustained light on center?

A

will fire and then return back to normal even if light remains same

99
Q

What info do P cells mainly provide?

A

contrast in retinal image

100
Q

What info do M cells mainly provide?

A

how image changes over time

101
Q

Whaat are the first photoreceptors to mature in retina?

A

intrinsically photosensitive gnaglion cells (babies can detect light before they can see images)

102
Q

What is a cycle when talking about grating?

A

1 black and 1 white stripe

103
Q

What determines the resolution acuity limit of spatial vision?

A

Spacing of photoreceptors in the retina

104
Q

How many cones per cycle do we need to properly perceive sine wave gratings?

A

2 cones per cycle

105
Q

What is horizontal and vertical asymmetry mean?

A

Vision falls of faster along vertical midline of visual field when compared to horizontal midline

106
Q

What does vertical meridian asymmetry mean?

A

Better acuity a fixed distance below the midline of visual field than above

107
Q

Is central or peripheral vision faster? Why?

A

Peripheral is faster

Foveal cones have longer axons because they are tightly packed

108
Q

High contrast sine gratings can be distinguished from a grey field is the stripes are separated by what?

A

At least 1 arc minute of visual angle

109
Q

What is spatial frequencies?

A

Number of times a pattern repeats in a given unit of space (visual angle)

110
Q

What does contrast sensitive function describe?

A

How the sensitivity to contrast depends on spatial frequency of stimulus

111
Q

What is the left y axis of CSF? How do we obtain the units?

A

Contrast sensitivity (starts at 1 goes up to 1000)

Taking reciprocal of right y axis

112
Q

What is the right y axis of CSF?

A

Contrast (%)

113
Q

How is contrast calculated according to michealson?

A

C= Lmax-Lmin/Lmax + Lmin

114
Q

What are some factors that influence the form of CSF?

A

Adaption level of eye, temporal modulation (how change over time), and age and refractive state of individual

115
Q

How does the visual system appear to break down images?

A

Components that are sine wave gratings with particular spatial frequencies

116
Q

What is Fournier analysis?

A

Procedure where any signal can be separated into component sine waves at different frequencies

117
Q

What is the phase of a sine wave?

A

It’s position relative to a fixed marker

118
Q

Where do the axons of the retinal ganglion cells end?

A

The lateral geniculate nuclei (on both sides)

119
Q

How many layers are in the LGN of primates?

A

6 layers

120
Q

What are the magnocellular layers of lgn? What about parvocellular?

A

1, 2 (inner most)

3, 4, 5, 6 (outer)

121
Q

What do magnocellular layer respond to vs parvocellular?

A

Large, fast moving objects VS details of stationary objects

122
Q

What are between the layers of LGN?

A

Koniocellular layers

123
Q

What projections reach the left LGN?

A

Left side of retina in both eyes

124
Q

What projections reach the right LGN?

A

Right side of retina in both eyes

125
Q

What layers receive info from the same eye?

A

2, 3, 5

126
Q

What layers of LGN receive info from opposite eye?

A

1, 4, 6

127
Q

How is the LGN mapped?

A

Topographically

128
Q

What larger brain structure is the LGN a part of?

A

Thalamus

129
Q

What are the other names of the primary visual cortex?

A

V1, area 17, striate cortex

130
Q

How many layers does V1 have?

A

6

131
Q

Where do the fibres from the LGN mainly project?

A

layer 4C, magnocellular ones go to upper layer (4Calpha), and parvo go to lower layer (4Cbeta)

132
Q

What is cortical magnification?

A

how different amounts of cortical area are dedicated to certain regions of visual field

133
Q

What did the earliest studies on cortical magnification/topography in humans use?

A

lesions on the cortex

134
Q

What is eccentricity?

A

disntace between retinal image and fovea, angular distance from fovea

135
Q

What do BOLD signals mean?

A

blood oxygen level dependent (fMRI)

136
Q

What is the extrastriate cortex?

A

V2-V4, MT(or V5)

137
Q

What is a consequence of cortical magnification?

A

visual acuity declines in an orderly fashion with eccrentricity

138
Q

What is the biggest obstacle to object recognition in periphery?

A

visual crowding, deleterious effect of clutter on peripheral object recognition (obejcts that are easily identified on own seem indistinct when surrounded by other objects)

139
Q

Why might visual crowding be essential?

A

simplifies appearence of objects in periphery by promoting consistent appearence

140
Q

How does the receptive fields differ between neurons in retina/LGN vs cortex?

A

not circular in cortex, more elongated (respond better to edges, lines, bars, gratings, rather than spots)

141
Q

What is orientation tuning? How much do they generalize?

A

cell is tuned to detect/respond to lines in a certain orientation

up to 30 degrees different they will still respond

142
Q

Which lines are cells least responsive to? Hozionrtal, vertical, or oblique?

A

oblqiue

143
Q

How do simple cells respond?

A

detect sine waves, are phase sensitive, detect more contrast

144
Q

How do complex cells respond?

A

detect sine waves, not phase selective

145
Q

What do we find for the first time in striate cortex?

A

orientation selective cells, motion selective cells, binocular cells that has varying degrees of dominance

146
Q

What is a diopter?

A

unit of measurement used for an eye prescription, expresses optical power of lens

PSYC 2220 (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions