Sensory Systems: Vision Flashcards
1
Q
The retina is _ - _ micrometers thick with _ output neurons.
A
100
200
3 million
2
Q
Liquid sphere is surrounded by 3 layers
A
Retina
Uveal layer
Sclera
3
Q
Retina
A
light sensitive receptors
4
Q
Uveal layer
A
Choroid
Ciliary body
Iris
5
Q
Sclera
A
White fibrous tissue with light-transparent cornea at front
body of eyeball
6
Q
Choroid
A
A layer of capillaries and melanin (the light absorbing pigment) behind the retina
7
Q
Ciliary muscle
A
Used to adjust lens
8
Q
Vertebrate eyes are oriented _____ & _____.
A
upside down
curved
9
Q
The cornea and lens bend the light to achieve a focused image (_____).
A
refraction
10
Q
Accommodation
A
changes in refractive power of the lens
11
Q
The lends is _____ to view distant objects and _____ to view near objects.
A
flat
round
12
Q
_____ keep the lens flat.
A
Zonule fibers
13
Q
Myopia (_% of US pop.) is the result of the cornea being _____ or the eyeball being _____.
(focus point _____ retina)
A
nearsighted 50 too curved too long before
14
Q
Hyperopia is known as _____ and results from refractory muscles being _____ or the eyeball being _____.
(focus point _____ retina)
A
farsighted
too weak
too short
behind
15
Q
Macula lutea and fovea form the region of _____.
A
highest visual acuity
16
Q
optic disk contains _____ photoreceptors.
A
no
17
Q
The _____ is the area of the retina where blood vessels enter and optic fibers leave the eye, creating a _____.
A
optic disk
blind spot
18
Q
_____ fill in the blind spot of the eye.
A
Cortical mechanisms
19
Q
The _____ is designed for acuity.
A
fovea
20
Q
The fovea is a _____ (composed only of _____) around _____ wide.
A
rod-free area
cones
200 micrometers
21
Q
Macular degeneration affects _____ people in the US.
A
6 million
22
Q
_____ is a loss of vision in the center of the visual field (the _____) because of damage to the retina.
A
Macular degeneration
23
Q
Macular degeneration ("dry" form)
(_% of all cases)
A
Debris between the retina and the choroid results in disappearance of the retinal pigment epithelium and loss of photoreceptors.
24
Q
Macular degeneration (“wet” form)
A
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
