Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIOL2052 S2 > Vision > Flashcards

Vision Flashcards

1
Q

With one quick look at something, what can we determine about it?

A
  • Shape
  • Size
  • Colour
  • Location
  • Speed
  • Direction
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

LO

A
  • Describe the anatomy of the eye, including the structure of the retina
  • Explain the function of rods and cones
  • Discuss the roles of on center and off-center ganglion cells
  • Describe the central visual pathways
  • Describe the concept of retinotopic organisation
  • Describe the columnar organisation in the visual cortex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

This is a diagram of the visual system

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

Visual field

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

What axons form the optic nerve in the eye?

A

The Retinal ganglionic cell axons

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

Where do the optic nerves cross?

A

Optic chiasm

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

Where does the optic nerves terminate?

A

Many terminate at lateral geniculate nucleus => relay to visual cortex (~40% of cortical area)

Others: pretectal nucleus (reflexive eye movements); suprachiasmatic nucleus (sleep – wake cycle)

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

Tell me the rough length of the eyeball?

A

roughly 25mm in length

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

What are the 3 layers of the eyeball?

A
  1. Sclera- tough and whiteish
  2. Choroid- all blood vessels
  3. Retina- photoreceptors present
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Label the eye

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

What fluid is the eyeball filled with?

A

vitrous humour

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

What parts of the eye are transparent?

A

Cornea

Lens

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

Tell me about refraction of light in the eye, whats involved and the light refraction they provide?

A

Refraction of light

  • Cornea provides most of refraction
  • Lens is adjustable => accommodation
  • Lens provides about a 1/3 of refraction. The lens is adjustable which allows us to see near and far. This is what we term as accommodation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Where does light collect in order to form the main image you see?

A

Fovea

rest of light collects and forms the peripheral image

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

What is meant by the blind spot?

A

Blind spot is where retina ganglionic axons leave the eye to go towards the brain this is void of photoreceptors

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

What layer of the eyeball forms the cornea?

A

Sclera turns really transparent and forms the cornea. This is the area that does the most refraction of light. Cornea provides most optical power

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

What is meant by the lens be accommodating?

Tell me what is involved in this to help this mechanism work?

A

Accommodation- changing your optical power to focus near and far

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

If your eye can see normally with no visual defects what is this known as?

A

Emmetropia

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

What are the two refractive errors in the eye and why do these occur?

A
  • Near sighted= myopia

​Nearsightedness usually occurs when your eyeball is longer than normal or your cornea is curved too steeply. Instead of being focused precisely on your retina, light is focused in front of your retina, resulting in a blurry appearance for distant objects

  • Far sighted= hyperopia

Farsightedness occurs when light is not refracted properly through an uneven, less smooth cornea or lens. It is a type of refractive error.

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

Which retinal ganglion cell axons cross into the contralateral hemisphere?

  1. All
  2. None
  3. Those coming from the nasal part of the retina
  4. Those coming from the temporal part of the retina
A

3

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

Where do the retinal ganglionic axons cross?

A

Optic chiasm

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

What structure of the eye provides most of the refraction?

A

Cornea

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

The retina, a view through the pupil

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

Is the retina considered part of the CNS or PNS?

A

CNS

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

What is the retina formed from?

A

The diencephalon (optic vesicle)

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

What are the 5 neuronal types in the retina?

A
  1. Photoreceptors
  2. Bipolar cells
  3. Ganglion cells
  4. Amacrine cells
  5. Horizontal cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

Label the layers of the retina

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

Label these cells of the retina

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

On the electromagnetic spectrum, what do the photoreceptors detect?

A

Visible light which is 400-700 nm

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

Where are the photoreceptors found in the retina?

A

Adjacent to RPE (retina pigmented epithelium)

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

What do the outer discs of photoreceptors contain?

Where is this regenerated?

A
  • Outer segment: discs containing pigment for light detection
  • Photopigment is regenerated in RPE
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Are the discs on photoreceptors replaced or do they stay there our entire life?

A

Discs are turned over (“shed”)

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

Tell me about light detection and the type of response it produced?

A

Light detected at outer segment leads to hyperpolarization => graded responses possible

Photoreceptors do not work with action potentials but with graded responses

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

In light and dark conditions

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

Tell me about opsins role in phototransduction?

A
  • Opsins sit within the membrane of a disc
  • Retinal is bound to opsins
  • Opsins tune sensitivity to particular wavelength
  • Light absorption leads to cis –> trans retinal
  • Light absorption => conformational change => activation of transducing => activation of cGMP hydrolysis
  • AMPLIFICATION!!
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

How is the phototransduction signal terminated?

A

[Ca2+] decreases (channels closed)

  • Guanylate cyclase activity increases (cGMP restored)
  • Rhodopsin kinase gets activated, phosphorylates rhodopsin  arrestin binding/ transducing displacement
  • All-trans retinol dissociates
37
Q

Light detection leads to?

  1. Depolarisation of the photoreceptor
  2. Hyperpolarisation of the photoreceptors
  3. Closing of Na+/Ca2+ channels
  4. Opening of the Na+/Ca2+ channels
  5. Closing of K+ channels
  6. Opening of K+ channels
A

2 and 3

38
Q

What are the Na+/Ca2+ channels gated by (ensures their opening)?

A

cGMP

39
Q

Tell me about rods and their sensitivity

A

Rods:

  • low spatial resolution
  • High sensitivity (1 photon can lead to a change to up to 1mv in membrane potential)
40
Q

Tell me about cones and their sensitivity?

A

Cones:

  • High spatial resolution
  • Low sensitivity (>100 photons)
  • Less saturation
  • Rapid recovery (deal with brighter light)
  • Mediate colour vision
41
Q

Label this diagram of a rod and cone

A
42
Q

How many light intensities can we see over?

A

We can see over a range of ~12 logs of intensities!

43
Q

What does loss of rod function lead to?

What does loss of cone function lead to?

A

Loss of rod function = night blindness
Loss of cone function = legally blind

44
Q

What colours can rods and cones see?

A
  • Trichromatic
  • “blue” (short), “green” (medium) and “red” (long wavelength) cones
  • Different cones are excited at different wavelengths

=> each cone is monochromatic!

  • Comparison of activity of different classes of cones to extract colour information
  • M and L are on X-chromosome
  • 3 different types of cones for different colours of light (short, medium and long)
  • Only one rod in the green light wavelengths
45
Q

Questions covered at end of lecture

A
  • Myopia linked to dopamine levels during development
  • Retina develops from diencephalon, therefore the most accessible part of the CNS, useful for disease diagnosis. As the brain and spinal cord are very well encapsulated
  • Spatial resolution is directly related to how well the light focuses on the retina for initial light detection
46
Q

The retinal ganglion axons terminate at the…

  1. visual cortex
  2. Latera geniculate nucleus
  3. optic chiasm
  4. suprachiasmic nucleus
  5. retina
  6. pretecal nucleus
A
  1. lateral geniculate nucleus
47
Q

The lens is adjutable to allow focussing over a range of distances. This is called what?

A

Accomodation

48
Q

Which statements are correct?

  1. light detection leads to hyperpolarisation
  2. light detection leads to the opening of voltage-gated channels
  3. light detection leads to the opening of cGMP- gated channels
  4. the biggest signal amplification upon light detection occurs at the stage of transducin activation
  5. the retinal pigmented epithelium regenerates 11-cis retina
A

1, 4 and 5

49
Q

Which of the following describes cones…

  1. provide low spatial resolution
  2. are monochromatic
  3. show low sensitivity/ low saturation
  4. mediate night vision
A

2 and 3

50
Q

Which three cells make up the simplest retinal circuit?

A

photoreceptors

bipolar cells

ganglionic cells

51
Q

which statements are true for an on-center bipolar cell…

  1. has AMPA/ Kainate receptors
  2. depolarises in response to light detection at the cone
  3. is sign-inverting
  4. silences on-center ganglion cells in response to light
A

2 and 3

52
Q

Visual acuity (Visual acuity refers to your ability to discern the shapes and details of the things you see)

A
53
Q

rods, cones and photoreceptors

A
54
Q

Is photoreceptor density constant across the retina?

A
55
Q

Differences of rods and cones

A
56
Q

Contrast and resolution

A
57
Q

Contrast and resolution- sensitivity

A
58
Q

What do ganglionic cells detect?

A

changes in luminance

59
Q

What is the receptive field?

A

Region in which a stimulus elicits an action potential

60
Q

retinal ganglionic cells

A
61
Q

Are receptive fields overlapping?

A

yes

62
Q

Are there equal numbers of on center and off center RGC?

A

yes

63
Q

Tell me about on/off-center cells

A
64
Q

RGC and on/off-center

A
65
Q

Response of an on-center GC

A
66
Q

edge detection

A
67
Q

Tell me whats involved in light adaptation?

A
  • Horizontal cells
  • Glutamate depolarises –> sign-conserving
  • releasing GABA to hyperpolarise photoreceptors–> inverting
68
Q

Tell me about horizontal cells

A
  • Connected via gap junctions
  • Network over large area of retina
  • Allows detection of background illumination
69
Q

dark adaptation

A
70
Q

Mach bands and Hermann grid

A

Mach bands is an optical illusion named after the physicist Ernst Mach. It exaggerates the contrast between edges of the slightly differing shades of gray, as soon as they contact one another, by triggering edge-detection in the human visual system.

The Hermann grid illusion is an optical illusion reported by Ludimar Hermann in 1870. The illusion is characterized by “ghostlike” grey blobs perceived at the intersections of a white (or light-colored) grid on a black background. The grey blobs disappear when looking directly at an intersection.

71
Q

Similar princiople for colour opponent RGCs and Mach and Hermann

A
72
Q

Rods…

  1. mediate achromatic vision
  2. are sensitive to scattered light
  3. are found at the fovea
  4. are much more abundant than cones
  5. mediate high acuity vision
A

1, 2 and 4

73
Q

Which statements are true for off-center ganglion cells?

  1. depolarise in response to glutamate
  2. activate when the center is brighter than the surroundings
  3. show a graded response to light
  4. connect to bipolar cells
  5. connect to horizontal cells
A

1 and 4

74
Q

Which cell(s) in the retinal circuit generate action potentials?

A

ganglionic cells

75
Q

Which cells in the retinal circuit surveys a large area to detect backgroun illumination?

A

horizontal cells

76
Q

The central visual pathway

A
77
Q

What do ganglionic cells in the optic tract project into?

When projecting into this area(s) what does it help coordinate?

A
  • Pretectum: feeds back to constrictor muscle in iris => pupillary light reflex
  • Suprachiasmatic nucleus (hypothalamus): circadian (day – night) cycle
  • Superior colliculus: coordination of movement in response to visual cues
  • Dorsal lateral geniculate nucleus: relayed to visual cortex (“seeing”)
78
Q

Optic nerve

A
79
Q

Where does the optic nerve project into?

Tell me about this projection?

A
  • Retina projection to dLGN (lateral geniculate nucleus)
  • Lateral Geniculate nucleus comes in layers
  • The retinal projection to the dLGN is a retinotopic point-to-point projection (no crossing)
80
Q

What arrangement is maintained throughout the visual pathway?

A

Spatial arrangement of the retina

81
Q

Retinotopic maps

A
  • Visual field maps
  • Disproportionate representation
82
Q

Focal lesions lead to focal visual loss

A

The diagram shows what area (A-E) has an effect on vision

83
Q

Neurons help to detect orientation and the following diagram shows the experiment that was carried out to look at this

A
84
Q

Explain this diagram with neuronal detection and orientation

A
  • Columns respond to one direction
  • Adjacent columns respond to progressive shifts
  • Deeper into columns they detect the same orientation
  • But as move along the layer they shift slightly and progressively
85
Q

What do oscular dominance columns show?

A

When one eye is dominant over the other

86
Q

Tell me how input is combined from both eyes?

A
  • dLGN: individual neurons are monocular
  • Terminate in alternating ocular dominance columns in cortical layer IV
  • Outside layer IV: binocular, but relative strength varies in columns
  • stereopsis
87
Q

Tell me about ‘hyper column’ in the visual cortex

A
  • responds stronger to one eye or the other and have orientation
  • as the diagram shows there are all different orientations by the neurons
88
Q

Tell me about higher order visual processing

A

This is a simple diagram but shows how it branches into different processing sections

  • Original input at photoreceptor is pixel-like
  • Higher order processing allows robust visual recognition
  • And selectivity

BIOL2052 S2 (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions