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MOVEMENT NEUROSCIENCE EXAM 2 > MODULE 6- The Visual System > Flashcards

MODULE 6- The Visual System Flashcards

1
Q

human visual system can detect only the ____ nm range of the entire electromagnetic spectrum

A

380-750 nm

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2
Q

how is visible light transmitted into the eye

A

some light source (e.g., sun, light bulb) emits light ->
to some object ->
light is reflected to our eyes

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3
Q

the wavelength corresponding to the color of the object we see is reflected/absorbed

A

reflected back to us

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4
Q

all other wavelengths that are not the color of the object we see are reflected/absorbed

A

absorbed

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5
Q

retina

A

-innermost layer of the eye
-contained > 100 million photoreceptors

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6
Q

ciliary body

A

contains a muscular component that shapes the lens

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7
Q

path of light

A

cornea ->
anterior chamber (aqueous humor) ->
pupil ->
lens ->
vitreous humor ->
fovea

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8
Q

projections of the visual field onto the ____

A

retina

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9
Q

what is in the center of the macula lutea

A

fovea

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10
Q

where is visual acuity the highest

A

fovea

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11
Q

scotoma

A

“blind spot”

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12
Q

scotoma (blind spot)

A

where the ganglion cell axons leave the eye + then become the optic nerve

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13
Q

there are no ____ in the scotoma (blind spot)

A

photoreceptors

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14
Q

visual field

A

the visual space that each eye sees

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15
Q

how is the visual field divided

A

-left + right sides (nasal + temporal halves)
-superior + inferior halves

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16
Q

overlap of the left + right visual fields gives ____

A

binocular depth perception

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17
Q

what causes image to be inverted (2)

A

cornea + lens

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18
Q

6 cell types in the retina

A

-rods + cones
-bipolar + horizontal cells
-amacrine cells
-retinal ganglion cells

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19
Q

rods + cones

A

photoreceptors in the outer nuclear layer

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20
Q

bipolar + horizontal cells

A

interneurons in the outer plexiform layer

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21
Q

amacrine cells

A

cell bodies in the inner nuclear layer

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22
Q

retinal ganglion cells

A

end cells in the inner plexiform layer

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23
Q

retinal ganglion cells axons exit the eye as the ____

A

optic tract

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24
Q

**quickest/most direct way for light transmission

A

cones/rods (photoreceptors) ->
bipolar cells ->
ganglion cells

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25
Q

the transmission of electrical signals in neurons propagates in the same/opposite direction of light

A

opposite

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26
Q

the tranmission of electrical signals in neurons propagates in the opposite direction of light via a ____

A

3-neuron chain

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27
Q

phototransduction

A

conversion of photons into electrical signals (transduced)

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28
Q

phototransduction is carried out by what

A

rods + cones

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29
Q

do rods + cones depolarize or produce APs

A

NO

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30
Q

light activation causes a graded depolarization/hyperpolarization of the membrane potential

A

hyperpolarization

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31
Q

light activation causes a graded hyperpolarization of the membrane potential which causes a change in what

A

the rate of neurotransmitter release onto postsynaptic neurons

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32
Q

pathway for cyclic GMP-gated channels + light-induced changes in the electrical activity of photoreceptors IN THE DARK

A

-cyclic guanosine monophosphate (cGMP) is in high concentration inside the cell
-cGMP binds to Na+ channels keeping them open
-allows Na to enter keeping membrane depolarized

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33
Q

pathway for cyclic GMP-gated channels + light-induced changes in the electrical activity of photoreceptors IN THE LIGHT

A

-cGMP concentration is reduced once light stimulates the region
-channels close
-leads to the receptor hyperpolarization

-both rhodopsin + opsin contain 11-cis-retinal ->
all-trans-retinal by a photon of light

-in the light, transducin: 2nd messenger activated -> PDE ->
cGMP hydrolyzed ->
closure of Na+ + Ca2+ channels

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34
Q

where are cones most highly concentrated

A

fovea
-then sharply decrease their numbers by as little as 10 degrees away

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35
Q

are there rods in the fovea

A

no

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36
Q

there are way more rods/cones numbers + density throughout the retina (besides the fovea)

A

rods

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37
Q

rods exhibit a high degree of ____

A

convergence

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38
Q

how many contacts does each cone have with a bipolar neuron

A

only 1 contact

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39
Q

rods/cones are much more sensitive

A

rods

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40
Q

how many photons does it take to activate a rod

A

1

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41
Q

how many photons does it take to activate a cone

A

greater than 100

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42
Q

rods have low/high spatial resolution

A

low

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43
Q

rods are/aren’t extremely light sensitive

A

are

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44
Q

rods operate well at low/high illumination levels

A

low

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45
Q

scoptopic vision

A

operating well at low illumination levels

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46
Q

rods are scoptopic/photopic

A

scoptopic

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47
Q

cones have low/high spatial resolution

A

high

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48
Q

cones are/aren’t sensitive to low light levels

A

aren’t

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49
Q

cones are highly sensitive to what type of light

A

bridge

50
Q

photopic vision

A

highly sensitive to bright light

51
Q

cones are scoptopic/photopic

A

photopic

52
Q

human vision is ____-chromatic

A

trichromatic

53
Q

trichromatic

A

3 different types of cones

54
Q

human vision has how many different types of cones

A

3

55
Q

how is a specific color detected

A

by comparing the activities of specific cones

56
Q

____% of U.S. males are color blind

A

8%
-more prevalent in males

57
Q

____% of U.S. females are color blind

A

1%

58
Q

receptive field

A

whether in the retina or in the visual center in the brain, every neuron will respond to a presence or property of light within a confined visual space around it

59
Q

receptive fields gain ____ with increased interactions with other neurons (e.g., bipolar cells) as distance from the retina increases

A

complexity

60
Q

when does ON-center ganglion fire APs

A

when illuminated in the receptive field

61
Q

when does OFF-center ganglion cell fire APs

A

when not illuminated (light is turned off)

62
Q

agonistic/antagonistic center-surround arrangement of their receptive fields

A

antagonistic

63
Q

ON + OFF pathways are in the ____

A

retina

64
Q

**what is the difference between ON/OFF bipolar cells

A

different glutamate receptors

65
Q

the different types of glu receptors for ON/OFF pathways allow cells to do what

A

respond to inrements + decrements in light levels

66
Q

photoreceptors always depolarize/hyperpolarize

A

hyperpolarize

67
Q

sign inverting (-)

A

if change in membrane potential of the bipolar cell is opposite of that in photoreceptor

68
Q

sign conserving (+)

A

if the change in membrane potential is the same for the photoreceptor + bipolar cell

69
Q

information supplied by retina (4)

A
  1. mediates the pupillary light reflex
  2. regulates circadian rhythms (day/night cycle)
  3. directs eyes to targets of interest
  4. leads to conscious perception of the visual scene
70
Q

principle pathway for visual perception

A

retina ->
lateral geniculate nucleus in the thalamus ->
primary visual cortex

71
Q

dinural

A

day/night

72
Q

**information goes DIRECTLY from ____ to all BUT the ____

A

-retina
-striate cortex

73
Q

hypothalamus function

A

regulation of circadian rhythms
-dinural

74
Q

pretectum function

A

reflex control of pupil + lens
-pupil

75
Q

superior colliculus function

A

orienting the movements of head + eyes
-eye movements

76
Q

striate cortex function

A

perception

77
Q

2 types of projections in the retino-geniculo-cortical pathway

A

-parallel
-retinotopic

78
Q

what cells carry feature information to the brain

A

retinal ganglion cells

79
Q

midget cells are also called

A

P cells

80
Q

parasol cells are also called

A

M cells

81
Q

midget (P cells)

A

project to 4 parvocellular layers of lateral geniculate

82
Q

parasol (M cells)

A

project to 2 magnocellular layers of lateral geniculate

83
Q

lateral geniculate receives input from the retina based on M/P cell type

A

both cell types
-and which eye (ipsilateral vs. contralateral)

84
Q

**lateral geniculate axons terminate in eye-dependent ____

A

ocular dominance columns

85
Q

lateral geniculate axons terminate in eye-dependent ocular dominance columns in ____ of primary visual cortex

A

layer 4

86
Q

stereopsis

A

binocular depth perception

87
Q

P cells have small/large receptive fields

A

small

88
Q

M cells have small/large receptive fields

A

large

89
Q

P cells have sustained/transient duration of response

A

sustained

90
Q

M cells have sustained/transient duration of response

A

transient

91
Q

do P cells transmit information about color

A

yes

92
Q

do M cells transmit information about color

A

no

93
Q

can P cells detect low-constrast stimuli

A

no

94
Q

can M cells detect low-contrast stimuli

A

yes

95
Q

fovea takes up ____% of retinal surface area

A

1%

96
Q

fovea supplies ____% of visual information to the visual cortex

A

50%

97
Q

the upper visual field is below the ____

A

calcarine sulcus

98
Q

much of the cerebral cortex engages in what

A

higher-level processing by integrating the information arriving at the primary visual cortex

99
Q

how many cellular layers of primary visual cortex

A

6

100
Q

what layers of primary visual cortex hold pyramidal neurons

A

2, 3, 5, 6

101
Q

what do pyramidal neurons do

A

release glutamate to subcortical + other cortical targets

102
Q

what does layer 4 of primary visual cortex have

A

spiny stellate cells

103
Q

layer 4 of the primary visual cortex is the primary target of what

A

extremely dense projecting axons from lateral geniculate

104
Q

`

primary visual cortex has what type of arrangement

A

columnar

105
Q

neurons within the same cortical column have the same/similar

A

receptive field properties + response preferences

106
Q

preferred orientation

A

the orientation of a stimulus to which a cortical neuron maximally responds

107
Q

preferred orientation is also called

A

peak of the tuning curve

108
Q

neurons in the primary visual cortex response ____ to oriented edges

A

selectively

109
Q

each class of orientation-selective neuron transmits what

A

only a small fraction of information in a scene
-the part that matches its filter properties

110
Q

assembling the information from all these different filters contains what

A

all the spatial information necessary to create a representation of a scene

111
Q

extrastriate visual areas

A

other cortical areas devoted to processing of information from the primary visual cortex
-hierarchial processing

112
Q

extrastriate visual areas use ____ processing

A

hierarchial processing

113
Q

ventral stream

A

recognizes the object/scene
“what?”

114
Q

pathway of ventral stream

A

primary visual cortex ->
inferior tempoeral cortex

115
Q

dorsal stream

A

analysis of motion + spatial relationships
-“where?”

116
Q

pathway of dorsal stream

A

primary visual cortex ->
medial temporal area

117
Q

patient with stroke in what is thought to be MT (visual motion processing area)

A

-had difficulty pouring tea in a cup
-fluid seemed to be frozen
-did no know when to stop because she was unable to perceive when the fluid had reached the brim
-had trouble sometimes following dialogue because she could not follow the movements of the speaker’s mouth
-could not cross streets easily- could not judge speed of approaching cars
-color + form intact

118
Q

MT is specifically involved in what

A

processing visual motion

119
Q

cerebral achromatopsia

A

-picture looks gray; may or may not be loss of acuity
-other aspects of vision are not working well
-when asked to draw an apple or school bus they cannot remember the appropriate color

120
Q

what works fine in cerebral achromatopsia

A

cone receptors

121
Q

cerebral achromatopsia is caused by damage to

A

extrastriate cortex (V4)

MOVEMENT NEUROSCIENCE EXAM 2 (15 decks)

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