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Visual Flashcards

1
Q

What happens during accomodation?

A

Ciliary muscle fibres contracted, suspensory ligs relaxed, lens thick

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2
Q

What does chromophore isomerise from and to?

A

11-cis to all-trans retinal

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3
Q

What does transducin activate?

A

Phosphodiesterase

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4
Q

What does Ca2+ inhibit?

A

Guanyly cyclase

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5
Q

Why does Ca2+ fall in light?

A

cGMP opens CNG channel

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6
Q

What is red dichromacy called?

A

Deuteranopia

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7
Q

What is green dichromacy called?

A

Protanopia

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8
Q

What is found in the outer nuclear layer?

A

Photoreceptor nuclei

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9
Q

What is found in the inner nuclear layer?

A

Bipolar horizontal and amacrine cells

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10
Q

What is invaginated within a cone pedicle?

A

Bipolar and horizontal

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11
Q

Layers of eye from the vitreous?

A

Inner limiting membrane, nerve fibres, ganglion cell bodies, inner plexiform, bipolar cells, outer plexiform, photoreceptor cell bodies, outer limiting membrane, rods and cones, pigment cells

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12
Q

What is the rod photoreceptor terminal called?

A

Rod spherule

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13
Q

Which is parvocellular?

A

For sustained input, colour-encoded, slow conduction

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14
Q

Which is magnocellular?

A

For rapid changes/motion, non-chromatic, high sensitivity, fast conduction, wide area, convergent

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15
Q

Which neurotransmitters do amacrine cells use?

A

All

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16
Q

Projections of retinal ganglion cells?

A

LGN, pretectum, SCN, superior colliculus

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17
Q

Where is right LGN input from?

A

Left temporal and right nasal

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18
Q

Where is left LGN input from?

A

Right temporal and left nasal

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19
Q

What is disparity?

A

Difference in angle at the two eyes

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20
Q

Where are illusory contours detected?

A

Cells in V2

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21
Q

Dorsal where pathway?

A

Magno > 4Calpha > 4B > thick > V3 for dynamic form

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22
Q

What does dorsal where pathway detect?

A

Visual flow

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23
Q

Other dorsal where pathway?

A

Magnocellular > LGN > V1 complex cells > V2 thick stripe > V5 or V5a

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24
Q

Parvocellular what pathway?

A

Parvocellular > LGN > V1 blob > V2 thin stripe > V4 colour

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25
Parvocellular/magnocellular what pathway?
LGN > V1 interblob > V2 interstripe > V4 form > infratemporal lobe (faces)
26
Which is the sign inverting synapse?
Cone depolarised to on centre bipolar cell
27
Which do horizontal cells inhibit when when they depolarise?
Cone
28
What happens when bipolar cell hyperpolarises?
Ganglion cell firing decreases
29
What is illuminance?
Intensity of incident light
30
What is luminance?
Intensity of reflected light
31
What is Weber's law?
R = change in I / I + Io
32
What is threshold contrast?
k = change in I / I
33
What is bleaching desensitisation?
Persistent excitation of phototransduction so reduced cytoplasmic Ca2+
34
What is bleaching adaptation?
decrease in sensitivity following very bright light
35
What is light adaptation?
Responds to the mean as illuminance increases so black always has lower luminace at any illuminance. A reversible change in sensitivity when steady intensity is altered.
36
What happens to spontaneous Rh* rate in the warm?
Lower absolute threshold
37
Which cells does dopamine reduce coupling between?
AII amacrine cells
38
Which signal flow does dopamine amacrine enable?
Via AII "rod" amacrine
39
What increases coupling in dark adaptation?
Dopaminergic A18 amacrine cells
40
How does dopamine affect gap junctions?
Decouples
41
Which kind of wavelength stimulates rods?
Short
42
What is flicker fusion frequency like in rods in the dark?
Low
43
Why is flicker fusion frequency better in the light?
Both rods and cones used
44
What is ouput of MT region?
Eye movements
45
What is input to MT and MST?
Movement - flow field (magnocellular)
46
What is the corneal stroma made of?
Parallel collagen fibres
47
What is the lens made of?
Crystallins
48
What does the rod outer segment contain?
Internalised discs
49
What regenerates rhodopsin?
Isomerohydrolase
50
What is retinitis pigmentosa?
loss of peripheral rod vision
51
What carries the dark current in the inner segment?
K+ out
52
What carries the dark current in the outer segment?
Na and Ca in
53
When are Ca levels high and when are they low?
High in the dark
54
What three things does calcium do?
R* activation, affects cGMP affinity, inhibits GC
55
Which channel is cGMP gated and closes?
NA
56
Where are the synaptic triads?
Cone pedicle
57
Which art of the cone establishes the receptive field of the bipolar cell?
Pedicle
58
Which LGN layers are parvocellular?
Four dorsal
59
Which LGN layers are magnocellular?
Two ventral
60
Other name for V1?
Striate cortex
61
How much of V1 is dedicated to the macula?
50%
62
Name of layer 4?
Stria of Gennari
63
Where do parvo and magnocellular terminate?
4C (beta for parvo, alpha for magno)
64
What do V1 cells respond best to?
Bars of light
65
Which layers are simple cells found in?
4 and 6
66
Which layers are complex cells found in?
2,3,5
67
What do V5/5a lesions cause?
Movement agnosia or akinetopsia (can't see motion)
68
Where are the cells which detect visual flow?
V5
69
Where does V5 go to?
Superior colliculus
70
Which areas do blob cell occur in?
Output layers 2 and 3 but not 4
71
Which animals are tetrachromats?
Birds and reptiles
72
Which pigments are in bird eyes?
Carotenoids
73
Who are dichromats?
Dogs
74
How is the signal representing luminance generate?
Responses of medium and long wavelength cones are summed together
75
What is the signal in the blue yellow opponent channel?
Differences between responses of the short wavelength cones and the sum of the medium and long wavelength cone responses
76
By which pathway do blue-yellow opponent cells pass to LGN?
Koniocellular
77
Where are the double opponent receptive cells?
V1
78
What do the red-green cones exhibiting centre surround antagonism signal?
Luminace
79
What are single opponent cells ambiguous for? What is used instead
Colour and brightness, double opponent
80
Where do double opponent cells project to?
V4 in area 18
81
Which cells respond best to coloured edges?
Subset of simple and complex cells in the interblob region
82
Where are the cells which mediate colour constancy?
Area V4
83
What does the threshold contrast encode?
Difference in intensity
84
What sets the absolute threshold?
The dark light
85
How does heat affect absolute threshold?
Lowers it
86
Which cells exhibit bleach-induce fluctuations?
Individual rods
87
What does dopamine do to coupling between AII amacrine cells?
Reduces
88
What is bleaching desensitization?
Persistent excitation of phototransduction
89
Which range are AII amacrine cells activated in?
Scotopic
90
What increase coupling in dark adaptation?
Dopaminergic A18 amacrine cells
91
What does dopamine released in the light do?
Decouples gap junctions
92
Why is flicker frequency better int he light?
Cones used

NAB (10 decks)

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