Liana Machado Eye Section Flashcards

1
Q

what is the pupil

A

the opening that allows light to enter the eye and reach the retina

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

what is the iris

A

a circular muscle that controls the size of the pupil (the coloured part)

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

what is the cornea

A

the transparent surface that covers the pupil and iris

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

what is the sclera

A

the “white of the eye”, it is continuous with the cornea

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

what is the lens

A

this helps focus rays of light on the retina

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

what is the retina

A

the internal lining of the rear two thirds of the eye, it converts images into electrical impulses that are sent to the brain

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

what is the macula

A

the central area of the retina that is specialised for vision

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

what is the fovea

A

this marks the centre of the retina and macula, the visual image received here is the least distorted.

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

what is the optic nerve

A

this is made up of axons and retinal ganglion cells, it carries impulses for vision from the retina towards the brain.

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

what is light to the eyes

A

light is electromagnetic energy that is emitted in the form of waves and is visible to the eyes.

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

what wavelengths are visible to the naked human eye

A

400-799 nm

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

how does visual information flow within the retina

A

photoreceptors - bipolar cells - ganglion cells

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

what does the retina convert

A

light energy to neural activity

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

what are the two types of photoreceptors

A

rods and cones

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

what are rods

A

rod-shaped structures that are specialised for low lighting.

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

what are cones

A

these are conical-shaped structures that are specialised for higher light levels and colour vision.

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

which part of the retina has more rods

A

the peripheral retina

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

which part of the retina has more cones

A

there is a higher concentration of cones in the central retina.

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

what is the process of visual information in the retina

A
  • light enters
  • information about the light flows from photoreceptors to bipolar cells to ganglion cells that project axons out of the eye.
  • axons of retinal ganglion cells carry information from eye to brain.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

why are bipolar and ganglion cells displayed laterally

A

to allow light to strike the foveal photoreceptors directly.

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

where is the blind spot

A

where the axons of the retinal ganglion cells exit the retina, there are no photoreceptors so sensation of light cannot occur.

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

what does our brain do to counteract the blind spot in our visual field

A

fill in our perception of these areas.

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

are images inverted on the retina

A

yes

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

the half of the retina that is closest to the nose is called the

A

nasal hemiretina

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

the half of the retina that is not close to the nose is called the

A

temporal hemiretina

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

at which degrees is the blind spot located in the temporal hemifield

A

15 degrees eccentrically.

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

because the optic disk is located in the nasal hemiretina, what affects the temporal hemiretina

A

the blindspot

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

the axons of the ganglion cells located in each nasal hemiretina go where

A

they cross the midline via the optic chiasm

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

the axons of the ganglion cells located in each temporal hemiretina go where

A

they dont cross the midline, they stay on their own side.

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

what happens if the optic chiasm is transected

A

peripheral vision will be lost bilaterally

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

what are axons of ganglion cells called before they cross at the optic chiasm

A

the optic nerve

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

what are axons of ganglion cells called after they cross the optic chiasm

A

the optic tract

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

where do the axons of the optic tract project to

A

superior colliculus
lateral geniculate nucleus of the thalamus

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

for subcortical vision, what is located in the retinotectal pathway

A

the retina and superior colliculus

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

for cortical vision, what is located in the retinogeniculostriate pathway

A

retina
thalamus (LGN)
primary visual cortex

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

what % of ganglion cells in the retina project to the superior colliculus

A

10%

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

what is the map in the superior colliculus

A

retinotopic map

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

where are the left and right LGN located

A

in the thalamus

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

what are the right and left LGN major targets of

A

the two optic tracts

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

where do most retinal ganglion cells synapse on to

A

LGN neurons

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

is the right LGN receives information, this comes from…

A

the left half of the visual field

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

where do most neurons in the LGN project their axons to

A

the primary visual cortex

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

what were the results of the ecstasy and V1 excitability study?

A
  1. that participants in the ecstasy group has a significantly lower phosphene threshold than participants in the control group. the frequency of ecstasy use correlated negatively with phosphene threshold.
  2. within the ecstasy group, the phosphene threshold of participants who hallucinated was significantly lower than the phosphene threshold of participants who didn’t hallucinate.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

what was the phosphene threshold

A

the minimum intensity that evokes phosphenes

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

what occurs if the TMS coil is placed over the primary visual cortex

A

when places over the occipital lobe, TMS can elicit light sensation (phosphenes) in the absence of visual stimuli

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

what is the ventriloquist illusion

A

the concept that speech seems to be coming from the puppets mouth rather than the puppeteers mouth

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

why does the ventriloquist illusion occur

A

occurs due to the sound source being mislocalised towards a synchronous by spatially discrepant visual event (in this case, the puppets mouth).

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

what is the visual cortex

A

this lies beyond the striate cortex in the extrastriate areas.

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

what can researchers identify with the use of single cell recording

A

they can identify the representational characteristics of neurons in different visual areas.

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

what is the experiment of single cell recording in the MT.

A

use of monkeys, are MT, looking at the activity of a single neuron being recorded when a white bar is passed through the neurons receptive field.
the found the neuron fired lots when the bar moved downward toward the left.
this meant that neurons in are MT are selective for the direction of motion.

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

what are the two cortical visual pathways of projection routes from primary visual cortex (V1) to extrastriate visual cortex

A

the dorsal stream and ventral stream.

52
Q

what does the dorsal stream code for?

A

motion and location

53
Q

what does the ventral stream code for

A

it processes detailed stimulus features and object identity

54
Q

where is V4 located

A

along the ventral stream

55
Q

what do the neurons in V4 respond to

A

they respond to mainly colour, but also form

56
Q

where is V5 located

A

it is located along the dorsal stream

57
Q

what do the neurons in V5 respond to

A

these neurons are selective for the direction of motion and speed of motion.

58
Q

what can damage to V5 do

A

this can disrupt motion perception which means the ability to discriminate the direction in which a stimulus is moved

59
Q

what % of axons in the optic tract target the retinogeniculostriate pathway

A

90%

60
Q

what are some general conclusions about the superior colliculus

A
  1. the superficial layers of the SC contain retinotopic maps of the visual field.
  2. the retinotopic map in the left SC represented the right hemifield.
  3. the retinotopic map is distorted, with more neurons devoted to analysis of the central portion of the visual field.
61
Q

what is the sprague effect

A

this is the restoration of orienting toward the cortically blind hemifield

62
Q

what is a basic summarisation of the Sprague effect

A

he lesioned the superior colliculus on the opposite side of the initial brain injury in hope to restore lost visual abilities because there is a reduction in the overactivity of the one side of the SC, helping the brain reroute an alternative visual pathway

63
Q

in the experiment of visual cortex vs superior colliculus damage, what two things were rodents trained to do

A

a localization task (turning their head toward a sunflower seed in the experimenters hand)

a discrimination task (running down a two-arm maze and entering the door which hid a sunflower seed.

64
Q

what occurred in the localisation task for the rodents with the lesions in the visual cortex

A

they performed normally for this, but not normally in the discrimination task.
the rodents with the bilateral disruption of the retinotectal pathway struggled on the localisation task but were fine on the discrimination task.

65
Q

what is blindsight

A

this the phenomenon where people who are blind in part of their visual field (usually due to brain damage) can still respond to visual information in the blind area even though they cant consciously see anything there.

66
Q

what happens when there is unilateral damage to primary auditory cortex (A1)

A

there is a surprising degree of normal auditory function retained.

67
Q

where are retinal ganglion cells located

A

they are located in the layers of the superior colliculus

68
Q

what is a saccade

A

this is a rapid eye movement

69
Q

neurons in deeper layers of the superior colliculus have …. field.

A

movement field - part of the visual field to which the eyes move in response to activity in the cells

70
Q

the movement fields of collicular neurons code for?

A

they code for eye movements in the contralateral hemifield

71
Q

neurons in the superficial layers recieve information from where

A

from retinal ganglion cells and contain a retinotopic map.

72
Q

the characteristics of the cells in the superior colliculus make them idea for?

A

detecting the location of visual events and triggering orientation responses.

73
Q

what is a reflexive saccade

A

a rapid eye movement in response to stimuli appearing the the periphery.

74
Q

what do reflexive eye movements help promote?

A

survival

75
Q

what is an exogenous eye movement

A

this is an eye movement driven by an external response

76
Q

exogenous =

A

external

77
Q

reflexive saccade =

A

exogenous saccade

78
Q

cells in deeper layers of the SC discharge during what

A

during saccades

79
Q

because of the organisation of cells, where are the smallest saccades represented

A

in the rostral superior colliculus

80
Q

because of the organisation of cells, where are the largest saccades represented

A

in the caudal superior colliculus

81
Q

what is the fixation reflex triggered by

A

an external visual stimulus projecting on to central vision.

82
Q

when a stimulus is presented at the fixation point, cells in which portion of the superior colliculus are activated?

A

in the rostral (front) area.

83
Q

what does FOE stand for

A

Fixation offset effect

84
Q

What does FOE provide

A

it provides a measure of the responsiveness of the fixation reflex, which a large FOE indicating a strong fixation reflex and a small FOE indicating a small one.

85
Q

what is an endogenous eye movement

A

this is a voluntary eye movement that is initiated internally

86
Q

what eye movements can be generated even in the absence of a visual stimuli

A

endogenous eye movements

87
Q

the superior colliculus which receives information directly from the retina projects down to what?

A

saccade generators in the brain stem

88
Q

what is the FEF

A

the frontal eye field

89
Q

where does the FEF project to

A

saccade generators in the brain stem

90
Q

reflexive eye movements depend on what structures

A

subcortical structures.

91
Q

voluntary eye movements depend on what structures

A

cortical structures in the brain.

92
Q

do reflexive eye movements require fewer or more neural connections compared to voluntary eye movements

A

they require fewer because there is less processing required.

93
Q

the superior colliculus is important for what type of reflexes.

A

oculomotor reflexes.

94
Q

in newborns, are subcortical or cortical structures already mature

A

subcortical structures

95
Q

What is FOE

A

this is a measure of how quickly you can shift your attention from one object to another

96
Q

at what age do infants often exhibit prolonged periods of fixation

A

at about 1 - 2 months old

97
Q

immaturity of cortical pathways in infants is also reflected in

A

reflected in their natural orienting behaviours.

98
Q

immaturity of the frontal cortex contributes to what in newborns

A

contributes to the fact that they exhibit a poverty of strategic behaviours, and instead are largely controlled by external stimuli

99
Q

at what age does the frontal lobes finally fully develop

A

around 15 - 20 years old

100
Q

what occurs in the anti-saccade task

A

you fixate on the centre, when a stimulus appears in the periphery, move your eyes in the opposite direction as soon as you can then return your eyes to the centre.

101
Q

the anti-saccade task requires the inhibition of what saccade?

A

a reflexive saccade.

102
Q

an abnormally slow correct reaction times on the anti-saccade task would suggest more of what?

A

more of a struggle in imposing voluntary control over reflexive behaviours.

103
Q

what is one part of the visual field that can come at a cost of neglecting other parts

A

attention

104
Q

overt shifts of attention involve what

A

they involve the movement of the eyes.

105
Q

covert shifts of attention involves what

A

they involve a mental shift of attention that doesn’t require the movement of the eyes

106
Q

exogenous shifts in attention are elicited by

A

by an external stimulus.

107
Q

what part of the brain is important for reflexive movements of attention

A

the superior colliculus

108
Q

what type of neurons are important for voluntary movements of attention

A

cortical neurons

109
Q

what does attention facilitate

A

responses

110
Q

inhibition of return is thought to facilitate what

A

facilitate efficient visual search by discouraging orienting towards recently attended locations.

111
Q

what is inhibition of return

A

this is the phenomenon where, after you briefly pay attention to a specific spot, you become slower to return your attention to it.

112
Q

inhibition of return provides an example of

A

reflexive mechanism of attention.

113
Q

what can the flanker task be used to assess

A

the efficacy of strategic control over attention (i.e., how easily distracted the participant it).

114
Q

what are the instructions of the flanker task?

A

maintain fixation on the centre of the screen. when a stimulus appears at the centre, indicate its identity by pressing the appropriate button as quickly as you can.

115
Q

the formation of what nervous system occurs during prenatal development

A

the central nervous system.

116
Q

the structure of the brain develops in what three steps

A
  1. cell division
  2. cell migration
  3. cell differentiation
117
Q

cell division is what

A

the first step in wiring cerebral cortex by generating cells

118
Q

cell differentiation refers to what process

A

the process, by which, after migrating, new cells take on the appearance and characteristics of a neuron or glial cell.

119
Q

within the wiring of the brain, neurons extend their axons to the appropriate targets to form…

A

interneuronal connections

120
Q

what is plasticity

A

this refers to the ability of the nervous system to change.

121
Q

is the adult or the postnatal brain more plastic

A

the postnatal

122
Q

what is the concept of plasticity

A

learning, growing the brains connections through retaining the information that we learn

123
Q

fine-tuning of the wiring of the brain is driven by…

A

neuronal activity

124
Q

do both eyes receive the same visual information?

A

no

125
Q

what is the background anatomy of the auditory system:

A

neurons in the inferior colliculus (IC) send their axons to the medial geniculate nucleus of the thalamus (MGN) which in turn send their axons to the primary auditory cortex (A1):
IC -> MGN -> A1

126
Q
A