Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

NEURO 0010 > visual > Flashcards

visual Flashcards

1
Q

where vs. what areas regarding vision?

A

where
- dorsal visual cortex areas

what
- ventral visual cortex areas

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

what is the cornea?

A

glassy transparent surface of the eye
-> it is continuous with the sclera
(white of the eye/wall of the eyeball)

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

what is the pupil?

A

the opening that lets light into the eye surrounded by pigmented iris
- iris = what gives eye its color

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

what is the lens?

A

located behind the iris and suspended by ligaments called zonule fibers (connected ciliary muscles)

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

how does the lens function in regarding to liquid in eye?

A

the lens divide liquid in eye into aqueous humor and vitreous

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

where is aqueous humor located?

A

behind cornea/in fornt of the lens

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

where is vitreous humor located

A

behind lens, keeps eye ball spherical

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

what is the retina?

A

area in the back of the eye that contains photo receptors

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

what is the optic disk?

A

where the retinal vessels originate and where optic nerve fibers exit
- there are no photoreceptors
- blind spot

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

what is the macula?
what does it contain?

A
  • yellowish region responsible for central vision
  • relatively lacks large blood vessels
  • contains the fovea
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

what is the fovea?
what are the distinctions of the fovea?

A

def: center of the retina

distinctions
nasal
- retinal surface closer to the nose/medial relative to the fovea

temporal
- retinal surface closer to temple/lateral relative to fovea

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

what is the specialization of the fovea?
where does this specialization come from?

A

specialized for high acuity vision

due to
- highest density of cone photoreceptors
- no blood vessels obscuring retinal surface
- inner retinal layers pushed aside

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

what is refraction in the eye?
- what are the index’s of refractions present in the eye

A

cornea
-> aqueous vitrus and humor
-> lens

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

what is the amount that light bends in the eye due to?

A

amount of bending is proportional to the index of refraction
- higher index = greater bending

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

what is unique about the cornea and eye refraction?

A

cornea contributes most to light refraction because it is the first part of the eye that the light hits

sharpest change in index refraction

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

what is the purpose of the lens in regards to refraction?

A

the purpose of the lens is to accommodate via modulation of the shape of the lens

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

what happens to light when the lens is fattened?

A

the light bends more

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

what are zonule fibers and ciliary muscles?

A

zonule
- the tiny thread-like fibers that hold the eye’s lens firmly in place

ciliary
- changes the shape of the lens when your eyes focus on a near object

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

lens and fibers: far object?

A

less bending -> flattens
- because object is already parallel

zonule = tight
ciliary = relaxed

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

lens and fibers: close object?

A

more bending-> fattens
- because object is not as parralell

zonule = loose
ciliary = tight

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

what are the 2 refractive errors?

A

myopia
- cant see far objects which require less refraction
myopia cause
- too much refraction
- eye is too long horizontally
solution
- concave lens

hyperopia
- cant see near objects which require less refraction
hyperopia cause
- too little refraction
- eye is too short horizontally
solution
- convex lens

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

what are the 5 classes of retinal neurons? (bottom to top)

A

1) photo receptors (rods, cones)
2) bi-ploar cells
3) horizontal cells
4) amacrine cells
5) ganglion cells

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

how many retinal layers are there? what are the types?

A

5
- 3 nuclear layers (cell bodies)
- 2 plexiform layers (synapses)
plexi = network of neurons

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

how do horizontal cells function?

A
  • they get input from photo receptors
  • influence photoreceptors and bipolar cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
how do amacrine cells function?
- get input from bipolar cells - influence bipolar and ganglion cells
26
what does the light hit first?
the ganglion cells
27
what do photoreceptors do? why are they unique?
they transduce light into a change in membrane potential they are the only light-sensitive cells in the retina
28
how do non photoreceptor retinal cells fire in response to light?
via direct or indirect synaptic connections
29
what is a unique property of disks that help with them absorb light?
light-sensitive photoreceptors help absorb light to trigger Vm changes
30
what is melanopsin, where is it located?
ipRGCs contain melanopsin, large RFs allow humans to synchronize behaviour to changes in light (circadian rhythm)
31
why are retinal ganglion cells unique?
1) because they are the only retinal cells to fire action potentials 2) they send axons out of the optic nerve
32
where do ganglion cells project to?
Thalamus - LGN (lateral geniculate nucleus)
33
rods. vs cones - appearance - light sensitivity - mid-light - concentrated in - types - color reception
34
what is rhodopsin?
rod pigment and functions like receptor for signal cascade
35
when is the acuity of rods best vs. cones?
rods - best in periphery in scotopic conditions cones - best in fovea in photopic conditions
36
what is visual acuity?
they eyes ability to distinguish between 2 points (spatial sensitivity of the eye)
37
what are the electrical currents within the photoreceptors?
- outward K+ - inward Na+
38
what is the inward current of the photoreceptors called, what is the current gated by?
Na+ current is called "dark current", because it is not based on light stimulation
39
how does light activate photopigment?
- photopigment is located in discs of the outer segments - light changes the confirmation (shape) of the photopigment
40
what is the Vm of photoreceptors in dark conditions?
Vm = -30mV
41
what are the 2 reasons why the photoreceptors have fundamentally different electrical activity?
1) they have more Na+ leak channels 2) Photoreceptors hyper-polarize to light
42
what keeps Na+ channels open?
secondary messenger cGMP keep Na+ channels open
43
what is opsin? what is retinal? what is bleaching, what does bleaching cause?
opsin - receptor protein (has 7 transmembrane regions like G protein-couples receptors) retinal - is pre-bound against opsin bleaching - light changes conformation of retinal -> it activates opsin - activates G-protein transducin - transducin activates PDE - reduces levels of cGMP - Na+ channels close, hyper polarization
44
what are different photoreceptors hyperpolarized by?
different wavelengths of light
45
what is the color we perceive based on?
it is based on the relative activation of R, G and B cones
46
is color a physical property?
no, color is a function of the mind - different species presumably experience color differently
47
where are each RGB pigment located?
Red and green = X chromosome Blue = chromosome 7
48
how do our eyes deal with sustained changes in light?
adaptation
49
what is adaptation?
changes in visual sensitivity when there is a sustained change in light level
50
what are the 2 kinds of adaptation?
1) dark adaptation (adapting to darkness) 2) light adaptation (adapting to light)
51
what are the mechanisms for adaptation?
1) pupil constriction or dilation 2) switch between rods and cones 3) Ca++ feedback in photoreceptors
52
how do pupils adapt to light?
high intensity of light -> constriction of pupils low intensity of light -> dilation of pupils *details* constriction - increases depth of focus reflex is consensual - shining light on one eye while other is covered will cause both to constrict
53
what is the range that you can see when adapting?
the more light, the photoreceptors will hyperpolarize - cones can only change over a 10^3 range of light intensity
54
how is cGMP synthesized?
cGMP is synthesized by guanylyl cyclase from GTP
55
how does each photoreceptor adapt? (group or independent)
- each photoreceptor adapts independently
56
what is an afterimage?
the image seen after adaptation
57
rod and cone adaptations low light vs. high light
low light - rods become higher input for ganglion cells high light - cones become higher input for ganglion cells
58
what do the 3 different types of opsin in the cones represent?
RGB red=long green=medium blue=short
59
what does right temporal see? what does right nasal see?
right temporal - left central right nasal - right peripheral - right central
60
what does left temporal see? what does left nasal see?
left temporal - right central field left nasal - left peripheral - left central
61
where do nasal portions decussate?
at optic chiasm
62
what do the optic tracts carry?
information from the contralateral visual field
63
what is the fovea specialized for?
high acuity vision - fovea's have the highest cone density - no overlaying blood vessels - inner retinal layers pushed aside
64
describe rod and cone distribution?
92 million rods 5 million cones 1.5 million axons leave the eye -> much signal processing in the eye
65
what is the result of the distribution of cones and rods in the eye?
blind spot color vision - best in fovea - poor in periphery - none at night acuity - best in fovea with photopic light - best in periphery with scotopic light (fins a star on a moonless night)
66
what is the receptive field of a neuron?
the field of stimulus to which a cell responds
67
what is the best or optimal stimuli for a cell?
the one that causes the maximal response
68
photoreceptor receptive field?
spot of light on retina
69
bipolar cell, ganglion cell, thalamus receptive field?
have center/surround antagonistic RFs ON-center/OFF-surround or OFF-center/ON-surround
70
V1 - receptive field?
Bar of light with a particular orientation
71
dorsal secondary visual area - receptive field?
spots of light moving in particular direction -> motion processing
72
ventral secondary visual area - receptive field?
biologically significant objects -> form/color processing - hand or a particular person
73
what do photoreceptors release when depolarized? what happens when there is more light?
glutamate more light = greater hyperpolarization -> less glutamate is released
74
what are the two types of bipolar cells?
On and Off
75
what is the purpose of lateral inhibition?
to enhance visual contrast
76
what are the cells that fire action potentials in the visual system?
retinal ganglion cells
77
what are the different types of retinal ganglion cells?
magno, parvo, nonM-nonP
78
describe magno RGCs
- 5% of RGCs - Large RFs - Color insensitive - Transient burst of APs
79
describe parvo cells
- 90% of RGCs - Small RFs - Color sensitive - Sustained discharge of APs as long as stimulus is present
80
describe nonM-nonP RGCs
- 5% of RGCs - small RFs - most are color sensitive - Poorly charachterized
81
what is the LNG?
a thalamic nucleus that relays information from the retina to the primary visual cortex.
82
where is the LGN located? why are there 2?
- It is located in the thalamus - There are 2 because the thalamus is a bilateral structure
83
What is the distribution of input in the LGN?
20% = retina 80% = V1
84
how many layers are in the LGN?
6
85
what layers of the LGN receive signals from the ipsilateral eye?
2, 3, 5
86
what layers of the LGN receive input from the contralateral eye?
1, 4, 6
87
what layers of the LGN receive input from the different types of RGCs?
1 & 2 = Magno 3, 4, 5 and 6 = Parvo Koniocellular = nonM-nonP input
88
LGN functions?
- thalamic relay between optic tract and V1 - dreams in burst mode - visual attention
89
what is the dorsal stream of the LGN?
Magno LGN -> 4C alpha-> 4B -> Occipital/Parietal
90
what is the ventral stream of the LGN?
Parvo LGN -> 4C beta -> 2/3 -> Occipital/Temporal
91
what is the occipital and temporal cortex related to?
identification and recognition
92
what is the occipital and parietal cortex related to?
motor, visual motion, visual control of action
93
what are retinotopic projections an example of?
topography/topographic maps
94
what is the significance of layer 4C?
1) inputs from the L and R eye remain segregated 2) Layer 4C is monocular, the last time in the visual pathway where input from the two eyes is separated 3) the receptive field properties are center/surround antagonistic RF
95
describe how V1 layers outside of 4C function? what do the V1 layers contain, and produce?
they are binocular but are still dominated by one eye depending on their proximity to left eye input in layer 4C or right eye input in layer 4C contain - cortical modules produce - ocular dominance columns
96
in what direction do ocular dominance columns run?
perpendicular to V1 layers
97
describe orientation selectivity?
certain orientation gives highest response and form orientation columns
98
what is orientation selectivity used for?
form perception
99
direction selectivity?
- makes up a subset of neurons that are orientation selective - response based on orientation and direction of movement - response is also grade
100
what is direction selectivity used for?
motion perception
101
what are the characteristics of a simple cell?
1) orientation selective 2) distinct on/off areas 3) center-surround RF inputs
102
what are the characteristics of a complex cell?
1) orientation selective 2) on/off areas overlap 3) presumably constructed from the summation inputs from multiple simple cells preferring the same orientation
103
parvo and konio factors?
- ventral and cortical areas - form and color - "what"
104
magno factors?
- dorsal cortical areas - motion - "where"
105
5 factors of the V1 cortical modules?
1) each cortical module is necessary and sufficient to analyze a particular point 2) removal -> blind spot in visual area 3) 2 pairs od ocular dominance columns 4) 2 complete samplings of all 180 of possible orientation columns 5) also contain 16 cytochrome oxidase blobs
106
what is achromatopsia?
cortical color blindness
107
akinetopsia
motion blindness
108
what is the purpose of the dorsal stream?
for analysis of visual motion and visual control of action "where"
109
describe area V5/MT?
- nearly all cells are direction selective - unlike V1 has direction columns - large RFs, responsive to stimulus motion direction
110
describe area MST?
- cells selective for types of motion - proposed purposes: navigation, directing eye movements, motion perception
111
what could damage in the dorsal stream cause?
akinetopsia
112
what is the purpose of the ventral stream? what could damage to this area cause?
for perception of visual world and recognition of objects "what" - prosopagnosia, inability to recognize faces
113
describe area V4? what could damage to this area cause?
- very large RFs with color and orientation selectivity - achromatopsia
114
what is area IT?
farthest extent of visual processing - faces, objects with biological significance - large RFs - may be important for recognition and visual memory
115
what is the area associated with face recognition?
fusiform face area
116
what 2 areas are in the dorsal stream?
area V5/MT area MST
117
what 3 areas are in the ventral stream?
area v4 area IT fusiform face area
118
in what layer of the V1 does LGN feedback occur?
layer 6 of V1
119
what layer of the V1 controls eye movements
layer 5
120
what happens during spiking mode?
LGN firing follows ganglion cell input
121
what happens during intrinsic burst mode? what role does it play?
LGN cut off from sensory input - dreams - visual attention
122
what is the function of orientation selectivity?
- form orientation columns - used for edge detection and form perception
123
what is the function of direction selectivity?
- used for motion perception
124
what do cortical modules contain that are important?
cytochrome oxidase blobs
125
what are the cytochrome oxidase blobs used for?
color perception/processing
126
what does the v1 contain? what are the functions of the v1?
contains 4C, 2, 3, 4A, 4B, 5, 6 - center and surround antagonistic RF similar to LGN - orientation selectivity - direction selectivity

NEURO 0010 (22 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions