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Flashcards in Vision Deck (145)
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1

Two organizational principles of V1

Topographical mapping and foveal magnification

2

Receptive fields maintain antagonistic center around, produced by combining outputs of LGN cells

Simple V1 cortical cells

3

Respond to stimuli shaped like bars or edges that have a particular slant or orientation (particular angle)

Simple V1 cortical cells

4

Processed in left hemisphere (not just right eye)

Right VF

5

Processed in right hemisphere (not just left eye)

Left VF

6

What does the dark do to photoreceptors?

Depolarizes. More glutamate

7

What range does the left eye see?

1-8

8

What wavelength causes the max response in middle cones?

530 nm

9

When the light entering the eye is focused in front of the retina and stint objects can't be seen sharply. Near sightedness

Myopia

10

How does the lens accommodate for near objects

Convex shape

11

Function similar to horizontal cells

Amacrine cells

12

How does the lens accommodate for far objects

Concave shape

13

Blind spot is created by this

Optic disk

14

Two types of this cell: diffuse (peripheral) and midget (fovea)

Bipolar cells

15

Represents brightness

Amplitude

16

Hardening of the lens. The capsule that encircles the lens becomes less elastic as well. Harder to focus on close things. Old sight

Presbyopia

17

Receptive fields replicate the info passed to them by the bipolar cells. Max response to dots of specific size. Sensitive to contrast

Ganglion cells

18

Colored area. Contains muscles that control the pupil

Iris

19

Most detail and best perception of color in this type of vision

Central vision

20

Long cone defect

Protoanomalous

21

Transparent disk that uses accommodation to focus light rays for near of far distances

Lens

22

Part of environment registered on retina

Visual field

23

No short cone

Tritanope

24

Integrate info from photoreceptors close to one another and communicate through graded potentials with bipolar cells

horizontal cells

25

Why is the cell depolarized in the dark?

Sodium channels are kept open by cGMP. Na+ is allowed in in the dark

26

Organizational principle of V1. Locations on retina and LGN correspond to locations in V1

Topographical mapping

27

How many cells in the visual cortex

200 million

28

Receives input from M ganglion cells. Respond best to large, fast moving objects

Magnocelluar LGN layers

29

What is light?

Particle and a wave. Moving waves of photons

30

How many other cortical areas participate in visual processing other than V1?

At least 12

31

How many ganglion cells are there and what does this mean for how they respond to photoreceptors?

1 million. They respond to many photoreceptors

32

What are the wavelengths for the visible light spectrum?

400-800 nm

33

Shows preferred stimulus size and orientation but not location within the visual field. Sensitive to unidirectional movement

Complex V1 cortical cells

34

What is akinetopsia? What is it associated with?

Cant process motion. Dorsal stream

35

No medium cone

Deuteranope

36

How do on center and off center cells work?

On center = light in center: depolarized. Light in surround: hyperpolarized.
Off center = Light in center: hyperpolarized. Light in surround: depolarized

37

How does light need to behave in complex V1 cortical cells?

It must be moving and in a certain direction

38

Four parts of a hyper column

Orientation columns, ocular dominance column, movement, and color

39

Back opening that lets in light

Pupil

40

Optic nerve target that is the pacemaker for circadian rhythms. Regulates sleep/wake cycles and receives small numbers of retinal axons

Suprachiasmatic nucleus in hypothalamus

41

Represents color or shades of gray

Wavelength

42

What type of potentials are produced by photoreceptors?

Graded potentials, not AP

43

Why is it harder to focus when you get older?

The lens hardens

44

Has 6 distinct stacked layers, keeps input from each eye separate, modifies flow of info based on levels of alertness

Lateral geniculate nucleus in thalamus

45

Larger receptive fields with no off regions

Complex V1 cortical cells

46

What happens to the shape of retinal when it is exposed to photons?

It straightens

47

What does having more types of cones cause?

A poorer ability to discriminate colors, it does not make it better

48

Receive input from P ganglion cells. Respond best to fine spatial details of stationary objects

Parvocellular LGN layers

49

What wavelength causes the max response in rods?

502 nm

50

What range does the right eye see?

2-9

51

What does bright light lead to?

Greater hyperpolarization

52

Organizational principle of V1. Central vision has more brain representation than peripheral vision

Foveal magnification

53

Direct input from single set of photoreceptors

Center

54

Theory stating color vision is based on exciting one color and inhibiting its opposite

Opponent process theory of color vision

55

Optic nerve target that projects to primary visual cortex (V1). Visual perception. 90% of retinal axons

Lateral geniculate nucleus in thalamus

56

No long cone

Protanope

57

Respond to light falling in receptive fields. Antagonistic center-surrounded organization. Lateral inhibition. Communicate through graded potentials with amacrine and ganglion cells

Bipolar cells

58

A visual defect caused by the unequal curing of one or more of the refractive surfaces of the eye, usually the cornea

Astigmatism

59

What path does light take?

It passes through cells then hits the photoreceptors?

60

Less detail and color perception in this type of vision

Peripheral vision

61

Six muscles that rotate the eye in all directions

Eye muscles

62

What are the optical functions of vision?

Capture light and form detailed spatial images

63

What is the correct term for colorblindness?

Color anomalous

64

Responds to lines of a single angle for single eye, made of simple cortical cells. Hyper column part

Orientation column

65

What is the stimulus for vision?

Light

66

What does light do to rhodopsin and what does it do to cGMP?

Light breaks down rhodopsin, releasing enzymes that break down cGMP

67

These cells are filled with light sensitive chemicals called photopigments

Photoreceptor cells

68

Contain lodopsin

Cones

69

What causes age related macular degeneration

Problems with the macula leading to blurred central vision

70

Area involved in visual processing towards the top of the head that plays an important role in processing motion. Areas MT and MST

The dorsal stream (where/how)

71

In this cell, the bipolar cell is depolarized (excite)

On center cell

72

Composed of opsin and retinal

Rhodopsin

73

Where does the nasal (central) view of each eye go?

Contralateral (opposite side)

74

Rods only, no cones or only one type of cones

Monochromats

75

Circular receptive fields found in retina and LGN are replaced with elongated stripe receptive fields in cortex

Visual cortex (striate cortex)

76

What happens when enzymes created by light breaking down rhodopsin break down cGMP?

Fewer Na channels remain open and the cell hyperpolarizes

77

About 50% of these fibers cross to opposite hemisphere at the optic chiasm

Optic nerve

78

What is the resting potential fo rod outer segments in complete darkness?

-30 mV. Depolarized

79

Part of the retina where light rays are most sharply focuses

Fovea

80

Why is the eye extremely sensitive to pain?

Many pain receptors on cornea

81

What wavelength causes the max response in long cones?

560 nm

82

Optic nerve target that guides head and eye movement, visual reflexes. Receives 10% of retinal axons

Superior colliculus in midbrain

83

Three targets of the optic nerve

Lateral geniculate nucleus (LGN) in thalamus, suprachiasmatic nucleus in hypothalamus, and superior colliculus in midbrain

84

In between layers of LGN

Koniocellular LGN layers

85

Layers 3-6 of LGN

Parvocellular LGN layers

86

What is cGMP?

A secondary messenger that keeps sodium channels open in in the dark to allow depolarization

87

Human have 3 different types: short, medium, and long

Cones

88

What is prosopagnosia? What is it associated with?

Face blindness. Ventral stream

89

A membrane on the retina that improves night vision in animals that have it, humans don't

Tapetum lucidum

90

Sensitive to dim light in the blue to green range of the EM spectrum (shorter end)

Rods

91

Defect in one type of cone

Anomalous trichromats

92

Theory supported by complementary colors and afterimage effects

Opponent process theory

93

5 steps in the visual pathway

1.) R and L visual field to retina
2.) Optic nerve to optic chiasm to optic tracts
3.) 90% to LGN of thalamus
4.) Optic radiations to primary visual cortex (V1) in occipital lobe
5.) Secondary visual cortices

94

What does dim light lead to?

Less hyperpolarization

95

Where does the temporal (outside) view of each eye go?

Ipsilateral (same side)

96

Where are the genes that produce photopigments?

X chromosome

97

What does the light do photoreceptors?

Hyperpolarizes. Less glutamate

98

Path from photoreceptors

Photoreceptors to horizontal cells to bipolar cells to amacrine cells to ganglion cells to axons of optic nerves

99

Shape of receptive field elongated (lines not donuts)

Simple V1 cortical cells

100

What are the neural functions of vision?

Transduce light into neural signals, then relay and process those signals

101

What are bipolar cells?

One receiving and one transmitting branch

102

Outer surface of the eye. Curved, transparent dome that initially bends incoming light

Cornea

103

Medium cone defect (most common)

Deuteranomalous

104

In this cell, the bipolar cell is hyperpolarized (inhibit)

Off center cell

105

Area involved in visual processing toward the bottom of the head important for object recognition. Areas V4, IT and fusiform face are (FFA)

Ventral stream (what)

106

Color theory based on combination of activity in short, medium, and long cones

Trichromatic theory

107

Also known as primary visual cortex, Brodmann's area 17, or V1

Striate cortex

108

Photopic vision (bright light), color, high acuity, high density near fovea, humans have 6 million

Cones

109

Receive input from bipolar, amacrine cells

Ganglion cells

110

Missing one type of cone

Dichromats

111

Layers 1 and 2 of LGN

Magnocellular LGN layers

112

Contain rhodopsin pigment

Rods

113

Complex cells in a hyper column

Movement

114

This energy is abundant, travels quickly, and in straight lines

Electromagnetic energy

115

How is the eye protected?

Located in bony orbit of the skull, cushioned by fat, eyelids/eyelashes/blinking, and tears produced by the lacrimal gland

116

Visual pigments made. Contains chromophore to capture photons and an opsin protein

Inner part of photoreceptors

117

Loss of transparency in the lens that can be solved with silicone implants

Cataracts

118

Also known as the young-helmholtz theory of color vision

Trichromatic theory

119

Innermost layer in back of the eye where light is converted to neural impulses. Contains visual interneurons and photoreceptors

Retina

120

Changing the shape of the crystalline lens to focus on objects of varying distance

Accommodation

121

Short cone defect

Tritanomalous

122

How is light wavelength determined in the trichromatic theory?

Total activity across all 3 cones is used

123

Requires more light the other photoreceptor to respond

Cones

124

What 3 things can happen when light hits an object?

Reflection, absorption, or refraction

125

Cytochrome oxidase blobs in hyper columns

Color

126

Where blood vessels and optic nerve leaves the retina there are no photoreceptors. Compensatory mechanisms

Blind spot

127

Transparent, gelatinous mass that fills space from cornea to pupil

Aqueous humor of anterior chamber

128

What percent of males and females have colorblindness?

8% of males an 0.5% of females

129

Form connections between bipolar, ganglion, and other types of this cell. Play a possible role in processing movement

Amacrine cells

130

Located at the center of the macula and comes into play with central vision

Fovea

131

Responds to input from either the L or R eye, but not both. Preferred orientation changes. Hyper column part

Ocular dominance column

132

Theory supported by color blindness

Trichromatic theory

133

Contains visual interneurons, photoreceptors, optic disk, macula, and fovea

Retina

134

Transparent, gelatinous mass that fills space from pupil to retina

Vitreous humor

135

When light entering the eye is focused behind the retina. Farsightedness

Hyperopia

136

Ganglion cell axons bundle together and exit each eye through the optic disk, forming this leaving each eye

Optic nerve

137

Nutrients from epithelium and visual pigment storage

Outer part of photoreceptors

138

Scotopic vision (dim light), no color, low acuity, high density in the peripheral retina. Humans have 120 million

Rods

139

Transmits imputes from retina to brain

Optic nerve

140

Produce APs. Axons leave the eye as the optic nerve

Ganglion cells

141

What wavelength causes the max response in short cones?

420 nm

142

Is there more neural activity in the dark or light?

Dark

143

Indirect input from horizontal cells connected to photoreceptors

Surround

144

How does a cell know when light is present?

It interprets the reduction of glutamate caused by hyper polarization as light

145

The happy condition of no refractive error. Perfect vision

Emmetropia