Brainscape's Knowledge GenomeTM

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


See full index

L2 Neural Circuits > Visual System > Flashcards

Visual System Flashcards

1
Q

What is the purpose of any sensory system?

A

To recognise and localise 3 types of stimuli:
- Food
- Mate
- Predator (danger)

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

Which brain areas are involved in visual processing? (2)

A
  • Lateral geniculate nucleus (LGN)
  • Primary visual cortex
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the 2 main pathways involved in visual processing in the cortex?

A
  • Ventral “what” stream
  • Dorsal “where” stream
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Where is the ventral stream located?

A

Starts in the primary visual cortex and extends into the inferior temporal lobe (round the side of the brain)

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

Where is the dorsal stream located?

A

Starts in the primary visual cortex and extends into the posterior parietal lobe (over the back of the brain)

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

What is the ventral stream responsible for?

A

Information about object identity

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

What is the dorsal stream responsible for?

A

Information about spatial location, speed, movement

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

What is the fovea? (2)

A
  • Area of the retina with the highest visual acuity
  • Contains cones
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are Muller cells?

A

Transparent cells present in the retina which guide light through the retinal tissue

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

What are the layers of the retina?

A
  • Photoreceptors (at the wall of the eye)
  • Outer plexiform layer
  • Bipolar cells
  • Inner plexiform layer
  • Ganglion cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is in the outer nuclear layer?

A

Photoreceptors

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

What is in the inner nuclear layer?

A

Bipolar cells

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

What is in the outer plexiform layer? (2)

A
  • Horizontal cells
  • Between photoreceptors and bipolar cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is in the inner plexiform layer? (2)

A
  • Amacrine cells
  • Between bipolar cells and ganglion cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which cells form the optic nerve?

A

Ganglion cells

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

What is the purpose of horizontal and amacrine cells? (2)

A
  • Modification of signalling between the other cells
  • Mainly inhibitory signalling via GABA
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What neurotransmitter do photoreceptors release?

A

Glutamate

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

What are the 2 types of photoreceptors?

A

Rods and cones

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

Where does phototransduction take place in photoreceptors?

A

In the membranes of the disks in the outer segment

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

What is the response of photoreceptors to light?

A

Hyperpolarisation

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

What kind of synapse does a photoreceptor have?

A

Ribbon synapse

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

What happens when photoreceptors are exposed to light? (3)

A
  • Light activates rhodopsin which activates a G protein coupled receptor (transducin)
  • Transducin activates PDE which cleaves cGMP into GMP
  • Channels close = hyperpolarisation = reduced glutamate release
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is PDE?

A
  • Phosphodiesterase
  • Catalyses the hydrolysis of cGMP into GMP
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What happens in photoreceptors in the dark? (3)

A
  • There are high levels of cGMP which binds to channels and allows the influx of cations
  • This causes depolarisation
  • Constant release of glutamate
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What are the 2 types of bipolar cells?

A

ON and OFF bipolar cells

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

What is the response of ON bipolar cells to light?

A

Depolarisation

27
Q

What is the response of OFF bipolar cells to light?

A

Hyperpolarisation

28
Q

Why do ON bipolar cells depolarise in response to light?

A

They have mGluR instead of AMPA receptors

29
Q

Which receptors do OFF bipolar cells have?

A

AMPA receptors

30
Q

Which proteins may be involved in the mechanism of ON bipolar cells? (2)

A
  • TRPM1 which is expressed in ON but not OFF cells
  • Nyctalopin which is required for the response of ON cells
31
Q

Where in the inner plexiform layer do OFF bipolar cells project into?

A

The section which is closer to the bipolar cell layer

32
Q

Where in the inner plexiform layer do ON bipolar cells project into?

A

The section which is closer to the ganglion cell layer

33
Q

What are the 2 types of ganglion cells?

A

ON and OFF ganglion cells

34
Q

Where in the inner plexiform layer do OFF ganglion cells project into?

A

Where the OFF bipolar cells project (closer to the bipolar cell layer)

35
Q

Where in the inner plexiform layer do ON ganglion cells project into?

A

Where the ON bipolar cells project (closer to the ganglion cell layer)

36
Q

What is a receptive field?

A

The area of the retina which activates a visual neuron when illuminated

37
Q

What is the organisation of the receptive field of bipolar cells?

A

Centre-surround organisation

38
Q

Why do you record opposite signals when shining light on the centre and periphery of a bipolar cell receptive field? (2)

A
  • In the centre of the receptive field, photoreceptors synapse directly onto the bipolar cell
  • In the periphery of the receptive field, photoreceptors connect to the bipolar cell via a horizontal cell which reverses the signal
39
Q

What happens to the membrane potential of an OFF bipolar cell if you shine light at the centre of its receptive field?

A

Hyperpolarises

40
Q

What happens to the membrane potential of an OFF bipolar cell if you shine light at the periphery of its receptive field?

A

Depolarises

41
Q

What happens to the membrane potential of an ON bipolar cell if you shine light at the centre of its receptive field?

A

Depolarises

42
Q

What happens to the membrane potential of an ON bipolar cell if you shine light at the periphery of its receptive field?

A

Hyperpolarises

43
Q

What is the organisation of the receptive field of ganglion cells?

A

Centre-surround

44
Q

Which cells in the retina fire action potentials?

A

Ganglion cells

45
Q

What happens to the rate of action potential firing from an ON ganglion cell if you shine light at the centre of its receptive field?

A

Action potential firing rate increases

46
Q

What happens to the rate of action potential firing from an ON ganglion cell if you shine light at the periphery of its receptive field?

A

Action potential firing rate decreases

47
Q

What happens to the rate of action potential firing from an OFF ganglion cell if you shine light at the centre of its receptive field?

A

Action potential firing rate decreases

48
Q

What happens to the rate of action potential firing from an OFF ganglion cell if you shine light at the periphery of its receptive field?

A

Action potential firing rate increases

49
Q

What happens when you illuminate the entire receptive field of a ganglion cell (diffuse light)?

A
  • Ganglion cell is not activated
  • Ganglion cells are designed to respond to differences in illumination within the receptive field
50
Q

What are the 2 major classes of ganglion cells?

A
  • Parvocellular
  • Magnocellular
51
Q

What is the difference between magnocellular and parvocellular ganglion cells? (2)

A
  • Magnocellular cells have a much larger dendritic tree than parvocellular cells
  • Parvocellular cells process information about colour/shape whereas magnocellular cells process information about motion
52
Q

Why do the receptive fields of ganglion cells have centre-surround organisation?

A

Inhibitory feedback from amacrine cells

53
Q

Why do the receptive fields of bipolar cells have centre-surround organisation?

A

Inhibitory feedback from horizontal cells

54
Q

Why might ganglion cells have an asymmetric dendritic tree?

A

Allows for detection of motion in a particular direction

55
Q

What is adaptation?

A

A change in the response to the same stimulus

56
Q

What is sypHy? (3)

A
  • pH inside a synaptic vesicle is low
  • Vesicle release releases neurotransmitter and H+
  • pH dependent fluorescence to detect synaptic activity
57
Q

What is iGluSnfr?

A

Fluorescence in the presence of glutamate

58
Q

Where does adaptation occur?

A

Starts in the retina and then downstream

59
Q

What are the types of adaptation?

A
  • Sensitisation (facilitation)
  • Depression
60
Q

What is the difference between sensitisation (facilitation) and depression?

A

In depression, the amplitude of the response gradually decreases but in sensitisation, the response amplitude starts off small and gradually increases

61
Q

How do the mechanisms of depression and sensitisation (facilitation) differ? (2)

A
  • Depression happens downstream of Ca2+ activity because Ca2+ levels remain constant throughout
  • Sensitisation happens upstream of Ca2+ activity because Ca2+ levels increase as the amplitude of the response increases
62
Q

What is the mechanism of facilitation?

A

Negative feedback from amacrine cells

63
Q

What is the mechanism of depression?

A

Depletion of the readily releasable pool (RRP)

L2 Neural Circuits (13 decks)

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