Brainscape's Knowledge GenomeTM

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


See full index

Neural Circuits > BMS248 Lecture 3 - Visual System > Flashcards

BMS248 Lecture 3 - Visual System Flashcards

1
Q

The right visual field activates which part of the brain?

A

The left half of the brain (and vice versa)

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

What is the function of the retina?

A

Image acquisition

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

Where does the retina project to?
What occurs there?

A

The Lateral Geniculate Nucleus (LGN)
Preprocessing of visual information

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

Where does the retina project to?
What occurs there?

A

The Lateral Geniculate Nucleus (LGN)
Preprocessing of visual information

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

Where does the LGN project to?
What occurs here?

A

Primary visual cortex (V1)
Main processing of visual information

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

What are the two main pathways in the primary visual cortex

A

Ventral and Dorsal streams
(Go from the V1 cortex to these areas)

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

What is the ventral stream involved in?
What area of the brain?

A

Object recognition
Inferior temporal cortex

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

What is the dorsal stream involved in?
What area of the brain?

A

Spatial location + speed
Posterior parietal cortex

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

What does the pupil do in regards to the retina?

A

Regulates the amount of light that falls on the retina

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

Which part of the retina does the lens focus the image onto?

A

Fovea

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

What is the fovea?

A

The part of the retina with the most cones + highest visual acuity

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

The rest of the retina has contains mostly what?
What does this mean for visual acuity?

A

Primarily rods
Smaller acuity - detects change in the periphery

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

What are Muller cells?
Where are they found?

A

Glial cells that light passes through and onto the photoreceptors (transparent)
Grow across entire retina

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

The retina consists of how many layers of:
1. Neurons
2. Synapses

A
  1. 3 layers of neurons
    Photoreceptor layer, Bipolar cell layer, Ganglion cell layer
  2. 2 layers of synapses - inner and outer plexiform layers
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the feedforward neurons in the retina? (Excitatory - glutamate)

A

photoreceptors, bipolar cells > ganglion cells

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

What are the feedback neurons in the retina? (Inhibitory - GABA)

A

Horizontal cells > (back onto the photoreceptors) - also inhibitory feedforward
Amacrine cells > (back onto the bipolar cells) - also inhibitory feedforward

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

From the photoreceptors to the ganglion cells what is the arrangement of neurons?

A
  1. Photoreceptors (back of retina)
  2. Horizontal cells
    OPL
  3. Bipolar cells
    IPL
  4. Amacrine cells
  5. Ganglion cells (front of retina)
17
Q

Phototransduction occurs where in photoreceptors?

A

The outer segment

18
Q

Rods are active in what kind of light?
Cones are active in what kind of light?

A

Rods: active at dim light
Cones: active at bright light

19
Q

In vertebrates, photoreceptors respond to flashes of light by what?

A

Hyperpolarisation - decrease in membrane potential

20
Q

What does cyclic GMP do on the membrane of photoreceptors and under what conditions?

A

Opens non-selective cation channels to keep the membrane depolarised in darkness

21
Q

What is the phototransduction cascade?

A
  1. Light changes conformation of rhodopsin receptors
  2. G protein cascade (Gt)
  3. Activation of PDE (converts cGMP to GMP)
  4. Decrease in cGMP
  5. Non-selective cation channels close
  6. Hyperpolarisation of photoreceptors
22
Q

What do photoreceptors constantly release from their synapses in darkness?
How does this change when they are activated by light - what does this effect?

A

Glutamate
Less glutamate is released, leading to hyperpolarisation of the photoreceptors - this affects bipolar cells

23
Q

What does an OFF and ON bipolar cell do in response to light and Dark
What receptors do they use?

A

In light the ON bipolar cells depolarise (Turn on) and the OFF bipolar cells hyperpolarise
In dark the OFF bipolar cells depolarise and the ON bipolar cells hyperpolarise

OFF use AMPAR
ON use mGluR

24
Q

What does an ON bipolar cell do in response to light?

A

Depolarise
mGluR so Na+ enters the cell causing depolarisation - allows us to see details in bright light

25
Q

What receptors do ON cells use?
Implications for cGMP?

A

mGluR - G-protein (Gi) - when glutamate binds channels close - less glutamate from photoreceptors therefore channels are open - depolarisation
Removal of cGMP is not required for ion channel closure

26
Q

What are the two proteins that are responsible for the mechanism of ON cell response and activation?

A
  1. TRPM1 (ion channel) - response
  2. Nyctalopin (proteoglycan) - activation
27
Q

OFF cells stratify where in the IPL?

A

Upper - closer to bipolar cells

28
Q

ON cells stratify where in the IPL?

A

Lower - closer to ganglion cells

29
Q

What is a receptive field?

A

Area on the retina which when illuminated activates a single visual neuron

30
Q

What is the centre-surround organisation of an ON centre bipolar cell?

A
  1. Illumination of centre - cell fires
  2. Illumination of surround - cell does not fire
31
Q

What is the centre-surround organisation of an OFF centre bipolar cell?

A
  1. Illumination of centre - cell does not fire
  2. Illumination of surround - cell fires
32
Q

The central part of the receptive field goes to what cell?

A

Photoreceptors - bipolar cell

33
Q

The surround part of the receptive field takes what pathway

A

Photoreceptors - horizontal cell - bipolar cell

34
Q

In an off bipolar cell - what happens when the centre is illuminated?

A

. Hyperpolarisation of photoreceptors in central part of receptive field
2. Glutamate stops being released
3. Bipolar cell hyperpolarises

35
Q

In an off bipolar cell - what happens when the surround is illuminated?

A
  1. Hyperpolarisation of photoreceptors in surround part of receptive field
  2. Horizontal cell hyperpolarises
  3. This stops hyperpolarising photoreceptors
  4. Bipolar cell depolarises
36
Q

receptive field of a ganglion cell does what?

A

Does not activate them - because they respond to differences in illumination with their centre/surround organisation

37
Q

What are the two major classes of ganglion cells?

A
  1. Parvocellular
  2. Magnocellular
38
Q

What are the characteristics of parvocellular (P) ganglion

A
  1. Small field/dendritic tree
  2. Sustained response
  3. Respond to form/colour
  4. Slow conduction velocity
39
Q

What are the characteristics of magnocellular ganglion cells? 10%

A
  1. Large field/dendritic tree
  2. Transient response
  3. Respond to motion/light
  4. Fast conduction velocity
40
Q

What is adaptation?

A

Decrease in activity/spiking rate

Neural Circuits (12 decks)

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