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Flashcards in Sensory Systems: Vision Deck (121):
1

The retina is _ - _ micrometers thick with _ output neurons.

100
200
3 million

2

Liquid sphere is surrounded by 3 layers

Retina
Uveal layer
Sclera

3

Retina

light sensitive receptors

4

Uveal layer

Choroid
Ciliary body
Iris

5

Sclera

White fibrous tissue with light-transparent cornea at front
(body of eyeball)

6

Choroid

A layer of capillaries and melanin (the light absorbing pigment) behind the retina

7

Ciliary muscle

Used to adjust lens

8

Vertebrate eyes are oriented _____ & _____.

upside down
curved

9

The cornea and lens bend the light to achieve a focused image (_____).

refraction

10

Accommodation

changes in refractive power of the lens

11

The lends is _____ to view distant objects and _____ to view near objects.

flat
round

12

_____ keep the lens flat.

Zonule fibers

13

Myopia (_% of US pop.) is the result of the cornea being _____ or the eyeball being _____.
(focus point _____ retina)

nearsighted
50
too curved
too long
before

14

Hyperopia is known as _____ and results from refractory muscles being _____ or the eyeball being _____.
(focus point _____ retina)

farsighted
too weak
too short
behind

15

Macula lutea and fovea form the region of _____.

highest visual acuity

16

optic disk contains _____ photoreceptors.

no

17

The _____ is the area of the retina where blood vessels enter and optic fibers leave the eye, creating a _____.

optic disk
blind spot

18

_____ fill in the blind spot of the eye.

Cortical mechanisms

19

The _____ is designed for acuity.

fovea

20

The fovea is a _____ (composed only of _____) around _____ wide.

rod-free area
cones
200 micrometers

21

Macular degeneration affects _____ people in the US.

6 million

22

_____ is a loss of vision in the center of the visual field (the _____) because of damage to the retina.

Macular degeneration

23

Macular degeneration ("dry" form)
(_% of all cases)

Debris between the retina and the choroid results in disappearance of the retinal pigment epithelium and loss of photoreceptors.

24

Macular degeneration ("wet" form)

Blood vessels grow from the choroid and the retina can also become detached.

25

Macular degeneration is treated with _____ and _____ to stop the growth of blood vessels (_____ form).

laser coagulation
medication
wet

26

5 classes of retinal circuitry neurons:

photoreceptors (rods & cones)
bipolar cells
horizontal cells
amacrine cells
ganglion cells

27

Three neuron chain of retinal circuitry:

photoreceptor
to bipolar cell
to ganglion cell

28

Horizontal and amacrine cells enable interactions between _____ and _____ to maintain contrast over different light intensities.

photoreceptors
bipolar cells

29

_____ cells form the optic nerve.

Ganglion

30

Rods and cones have _____ and _____ segments.

inner
outer

31

In the dark, photoreceptors are _____.

depolarized

32

Light stimulation _____ photoreceptors.

hyperpolarizes

33

Photoreceptor potentials are _____.

graded

34

The outer segment of photoreceptors is responsible for _____.

depolarization (Na+ and Ca++ influx)

35

The inner segment of photoreceptors is responsible for _____.

hyperpolarization (K+ outflux)

36

Light reduces _____ and _____ channels.

cGMP levels
closes

37

_____ is coupled to one of several opsins (for _____)

Retinal
different wavelengths

38

Light photon converts _____ to _____.

11-cis retinal
all-trans retina

39

Conversion of retinal actives _____.

transducin

40

Transducin activates _____ (cGMP phosphodiesterase) which _____ levels of cGMP.

PDE
reduces

41

The rod system is _____ to light.

extremely sensitive

42

the rod system has a _____.

very low spatial resolution

43

The cone system is _____ sensitive.

low-light

44

the cone system has _____.

high spatial resolution

45

the cone system is responsible for perception of _____.

color

46

_____ vision uses both rods and cones

Mesopic

47

_____ vision uses no cones.

Scotopic

48

Cones have a _____ density throughout the retina.

low

49

_____ have a shark peak in density at the center of the fovea (_____).

Cones
foveola

50

Individual cones _____ in the fovea.

become smaller

51

Rods have a _____ density throughout the retina.

high

52

Rods have a _____ in density in the fovea.

sharp drop

53

The _____ contains no capillaries.

avascular zone

54

Cones adapt more efficiently to _____, while rods saturate _____.

constant illumination
quickly

55

Cones are connected _:_ to bipolar cells.

1
1

56

Rods show _____ at bipolar cells which _____.

convergence
increases light sensitivity

57

_____ vision uses mainly cones.

Photopic

58

Humans normally have _____ kinds of cones, resulting in _____ vision

3
trichromatic

59

L for _____ respondes to _____ wavelengths (peaking at _____)

long
long
red

60

M for _____ responds to _____ wavelengths (peaking at _____)

medium
medium
green

61

S for _____ responds to _____ wavelengths (_____, 5-10% and absent from _____)

short
short
blue
fovea

62

_% of males are colorblind.

8

63

_____ results in the loss of long (_____) wavelength perception.

Protanopia

64

_____ results in loss of medium (_____) wavelength perception.

Deuteranopia

65

_____ results in loss of short (_____) wavelength perception

Tritanopia
blue-yellow

66

_____ center cells increase firing when luminance increase in their receptive field center.

on-center

67

_____ center cells increase their firing when luminance decreases in their receptive field center.

off-center

68

On- and off-center ganglion cells have selective connections with on and off _____.

bipolar cells

69

Selective responses of on and off bipolar cells are due to their different _____.

glutamate receptors

70

_____ on "off"-center cells _____ the bipolar cell.

AMPA receptors
depolarize

71

_____ on "on"-center cells close _____ channels, leading to _____.

mGluR6
Na+
hyperpolarization

72

Center vs. surround properties of ganglion cells are shaped by _____ from _____.

lateral inhibition
interneurons

73

Antagonism of the surround area arises from _____ from horizontal cells.

lateral connections

74

Horizontal cells are depolarized by _____ from photoreceptors.

glutamate

75

__% of ganglion cells cross at the optic chiasm.

60

76

_____ for the optic nerve.

ganglion cell axons

77

The _____ contains info from both eyes.

optic tract

78

The optic tract leads to the _____, _____, _____ and _____.

dorsal lateral geniculate nucleus of thalamus
suprachiasmatic nucleus of hypothalamus
pretectum
superior colliculus (midbrain)

79

The _____ is involved with reflex control of pupil and lens.

pretectum

80

The _____ regulate constriction of the iris.

ciliary ganglions

81

Pupilliary reflex should be _____ for both eyes.

identical

82

Afferents from the pretectum lead to the _____, then the ciliary ganglions.

Edinger-westphal nucleus

83

The crossing of light rays through the lens casuses the images of objects to be _____ and _____ on the retina.

inverted
left-right reversed

84

The left half of the visual world is represented in the _____ half of the brain.

right

85

Ganglion cells in the _____ of each retina cross in the optic chiasm.

nasal division

86

Projections of cells tat lie in the _____ stay on the same side.

temporal division

87

The fovea is represented disproportionally large in the _____, while the peripheral stimuli are represented _____.

posterior striate cortex
further anterior

88

A lot more ganglion cells are in the _____ to process focused binocular vision.

macula

89

_____ (top) carries info about the contralateral superior visual field (inferior retinal quadrants)

Meyer's loop

90

_____ (bottom) carries info about the the contralateral inferior visual field (superior retinal quadrants).

Baum's loop

91

Scotomas

small visual field deficit

92

Anopsias

large visual field deficits

93

Inputs from the right hemi-retina of each eye project to different layers of the _____.

right lateral geniculate nucleus (LGN) of thalamus

94

The LGN is comprised of the _____, _____ and _____ layers.

magnocellular
koniocellular
parvocellular

95

Mangocellular layers are _____.

ventral layers (1-2), large neurons

96

Parvocellular layers are _____.

dorsal layers (3-6), small neurons

97

The magnocellular layers are layers _____ of the VC.

4C-alpha

98

The parvocellular layers are layers _____ of the VC.

4C-beta

99

The koniocellular layers are patches in layers _____ of the VC.

2/3

100

The _____ is important for spatial resolution.

parvocellular pathway

101

The _____ is important for high temporal resolution.

mangocellular pathway

102

The _____ details analysis of shape, size and color of objects.

parvocellular pathway

103

The _____ transmits some color information.

koniocellular pathway

104

The _____ evaluates location, speed and direction of a fast-moving object.

magnocellular pathway

105

Magnocellular ganglion cells have _____ and are _____ (respond only _____).

large receptive fields
fast
transiently

106

Parvocellular ganglion cells transmit _____ and are _____.

color information
persistently active

107

Magnocellular ganglion cells transmit _____ than parvocellular ganglion cells.

faster

108

Cells in the primary visual cortex respond _____ and have a _____.

selectively to oriented edges
preferred direction

109

_____ respond best to a bar of light with a specific orientation.

simple cells

110

Cells in the VC integrate inputs from _____ ganglion/LGN cells.

several

111

on- and off-center cells reside in the _____ and _____.

retina
LGN

112

The receptive field of _____ in the VC are built from the fields of several simple cells.

complex cells

113

Axons from LGN terminate primarily on spiny stellate cells of _____.

layer 4C (afferents to VC)

114

Pyramidal cells in _____ project to higher order (visual) cortices.

layers 2/3

115

Pyramidal cells in _____ project to subcortical areas, including LGN and superior colliculus.

layers 5/6

116

In the LGN, the inputs from both eyes are separated in _____.

different layers

117

Distinction is maintained is the VC in _____.

ocular dominance columns (layer 4 inputs)

118

Neurons outside layer 4 integrate inputs from _____.

both eyes

119

Blobs are groups of _____ neurons.

color-sensitive

120

Blobs are typically stained with _____.

cytochrome oxidase

121

Interblobs receive the same input but are sensitive to _____.

orientation