Week 2 Flashcards

(24 cards)

1
Q

Draw the Retina

A

In W2 Answers

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2
Q

If the eye only transmits borders, why do I see objects as a whole/complete?

A

Some non-edge information is transmitted, and the brain decodes the info from the eye to fill in the blank

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3
Q

What are the consequences of compression?

A

Very sensitive to sudden changes
Very poor at detecting slow changes
High resolution for b and w
Good at comparing things side by side
Surrounding context affects what we perceive

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4
Q

How does the eye grab info from the world?

A

A region in the sensory periphery influences the electrical activity of photoreceptors; each photoreceptor receives a small part of info from the visual landscape

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5
Q

What are receptive fields?

A

The light that the retina cells receives from a small part of space

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6
Q

How are receptive fields involved in vision?

A

Photoreceptors only respond when light falls on their receptive field, whose output (action potentials) in retinal ganglion cells whose axons form the optic nerve

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7
Q

What is the consequence of centre surround antagonism known as?

A

Simultaneous contrast illusion

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8
Q

Explain how the Craik O’Brien Illusion works

A

Normal image gets converted to edges (as ganglion cells only respond to them), and the rest of the brain interprets them as if they are the same (filling in)

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9
Q

Name an effect due to lack of crisp edges

A

Spatial location is not signalled well (results in filling in)

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10
Q

What is Troxler fading?

A

If a stimulus stays on for a long time it will appear to fade away

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11
Q

Why do we see an after image once a stimulus is removed?

A

The time lag on the inhibition produces the negative after image

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12
Q

What colour do K cells detect?

A

Blue-yellow

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13
Q

What is the difference between P cells and M cells:

A

P Cells:
slow response; red-green; fovea dominant; fine detail

M Cells:
fast response motion and depth sensitive, peripheral dominant, coarse detail

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14
Q

Name 2 characteristics of the LGN

A
  1. Each layer contains a complete retinotopic representation of 1/2 visual field
  2. No cell in each half of the LGN receives input from both eyes; but each LGN receives input from both eyes
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15
Q

What occurs in the Dorsal pathway?

A

‘Where’ -> Objects are in space, motion and depth

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16
Q

What occurs in the Ventral pathway?

A

‘What’ -> Recognising faces, places object s

17
Q

What does a stroke in the FFA lead to?

A

Problems recognising faces (prosopagnosia)

18
Q

What does a stroke in the STS lead to?

A

Recognising emotion (capgras syndrome)

19
Q

Which brain areas are multi-functional?

20
Q

Which brain areas are in the ‘what’ pathway?

21
Q

Describe the pathway for the output of the eye

A

Photoreceptors (rods and cones) > bipolar cells > retinal ganglion cells (of whose axons form the optic nerve)

22
Q

What is the difference between and on-centre and off-centre receptive field?

A

On-centre: when light shines on middle of receptive field = increases firing rate
Off-centre: when light shines on outer region = increases firing rate

23
Q

What do retinal ganglion cells respond best too?

24
Q

Describe the LGN

A

A bilateral structure with a L and R hemisphere; information starts to get separated in terms of colour and motion