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PSYC 211 (Behavioural Neuroscience) > Vision > Flashcards

Vision Flashcards

1
Q

Discuss sensation vs perception

A

Sensation: Involves cells of the NS that are sensitive to their environment
Perception: the conscious experience and interpretation of information

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2
Q

Hue?

A
  • Wavelength of light
  • What we perceive as colour
  • Determined by length
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3
Q

Brightness?

A
  • Intensity of light

- Determined by amplitude

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4
Q

Saturation?

A

-Relative purity of light

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5
Q

Electromagnetic spectrum of visible light?

A

400-700 nm, from blue (higher energy, shorter wavelength to red, lower energy and larger wavelength)

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6
Q

How is information from SR in the eye transmitted to the brain?

A

Through sensory transduction

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7
Q

How do we see?

A

By focusing an image on our retina, helped by the extraocular muscles attached to eyes

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8
Q

What regulates the amount of light entering our eyes?

A

Iris

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9
Q

What focuses the entrance of light into the eye?

A

The Cornea

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10
Q

What are the 3 celllular layers of the retina?

A
  • Photoreceptors (cones/rods)
  • Bipolar
  • Ganglion
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11
Q

What is the fovea? Where is it located? what does it allow for?

A
  • Region of the retina which allows for the most acuity of vision as it exposes cones only (other layers pushed away)
  • Allows for better acuity and colour processing
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12
Q

(T/F) there are more cones than rods in the retina

A

F, there are more rods

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13
Q

What is the optic disk?

A

Place in the retina where there are no PR, therefore the blind spot

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14
Q

Discuss 4 key characteristics of cones

A
  • Most prevalent in the central retina (fovea)
  • Sensitive to mod/high light
  • Provide info about hue
  • Provide acuity
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15
Q

Discuss 4 key characteristics of rods

A
  • Most prevalent in the peripheral retina, NOT found on the fovea
  • Sensitive to low levels of light
  • Provide monochromatic information only
  • Provides poor acuity
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16
Q

What are the two other cells in the retina layers?

A
  • Horizontal cells

- Amacrine cells

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17
Q

Discuss horizontal cells

A

Connect adjacent PR and the neuroprocesses of bipolar cells

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18
Q

Discuss amacrine cells

A

Connected to ganglion cells and the neuro processes of bipolar cells, transmitting information from BP –> GC cells

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19
Q

Name the two theories of perception of colour in the retina

A

1) Trichromatic coding

2) Opponent-Process coding

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20
Q

Discuss trichromatic coding in the retina

A

In TC, the eye will detect different colours b/c it contains three different types of receptors.

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21
Q

What are the three types of receptors in TC?

A

1) Short wave CR=blue
2) Medium wave CR=green 3) large wave CR= Red
- All of these are opsin receptors

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22
Q

If there is a defect in the CR, according to TC, what are the three types of genetic defects of colour? (PDMT)

A
  • Protanopia
  • Deutranopia
  • Tritanopia
  • Monochromatic vision
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23
Q

What is protanopia?

A

Difficulty seeing red, red cones filled with green opsin

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24
Q

What is deuteranopia?

A

Difficulty seeing green, green cones filled with red opsin

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25
Q

What is tritanopia?

A

Difficulty seeing blue, blue cones are lacking completely

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26
Q

T/F in tritanopia, people have difficulty seeing blue b/c their blue cones are full of yellow opsin

A

F, their blue cones are lacking completely

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27
Q

What is monochomatic vision?

A

All three cones (blue, red and green) are defective

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28
Q

What happens when their is a summation of activity when blue, red and green PR are activated?

A

Summation produces the perception of white colour

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29
Q

In opponent-processing coding, which neurons are most considered?

A

Receptive fields of colour-sensitive ganglion cells

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30
Q

Discuss the OPC

A

Neurons will respond to opposing pairs of primary colours, where the retina contains two kinds of colour sensitive ganglion cells (Red-green and yellow-blue), this may explain why we never see “reddish-green)
-When the receptor is illuminated with a complementary colour (i.e. green), it will decrease the cells firing of its complementary colour (i.e. red), whereas blue and yellow are untouched, which is why we could see blueish green and yellow-ish green (only red is shut off)

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31
Q

In OCP, discuss what happens when red light stimulates a red cone

A
  • Red cones transmit an EPSP to the R/G ganglion cells

- R/G ganglion cells are red when ON, and green when OFF

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32
Q

R/G ganglion cells are ___ when ON, and ___ when OFF

A

Red

Green

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33
Q

In OCP, discus what happens when green light hits a green cone

A
  • Green cone transmits an IPSP to the R/G ganglion cells

- R/G ganglion is red when ON and green when OFF

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34
Q

In OCP, what happens when yellow light hits the retina?

A
  • Stimulates the red and green cones equally
  • Red cone sends EPSP to R/G ganglion and Y/B ganglion
  • Green sends EPSP to Y/B ganglions and IPSP to R/B ganglion
  • The G/R ganglion is cancelled out, and the Y/B ganglion is excited, thus turns yellow
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35
Q

The Y/B ganglion is ___ when ON and ____ when OFF

A

Yellow

Blue

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36
Q

In OCP, what happens when blue light stimulates a blue cone?

A
  • Blue light sends an IPSP to the Y/B ganglion, is inhibited and becomes blue
  • Y/B ganglion is ON when yellow, and OFF when blue
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37
Q

What happens when the yellow cone is stimulated in OCP?

A

There are no yellow cones, only red, blue and green. Yellow light is from the red/green cones signalling two different types of ganglions

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38
Q

What is the first step in visual perception?

A
  • Converting the external stimulus to internal stimulus

- Where photopigments are responsible for the transduction of this light energy and change in membrane potential

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39
Q

What is the receptive field? Where is it located?

A
  • The visual stimulus must be located in the receptive field to produce a response in the neuron
  • Location depends on the location of photoreceptors
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40
Q

In the receptive field, what are the two main areas of photoreceptors?

A
  • Fovea (has less PR, lots of cones and smaller receptive field) –> Central vision
  • Periphery has more PR, but less acuity –> Peripheral vision
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41
Q

What type of ganglion cell are located in the receptive fields to produce central/peripheral vision?

A

-ON/OFF ganglion cells

42
Q

In C/P vision, when will an ON GC fire the most strongly?

A

When light hits the centre of it’s field

43
Q

In C/P vision, when will an OFF GC fire the most strongly?

A

When light hits it’s surround area

44
Q

In an OFF cell, what happends when light hits both it’s on/off areas?

A

It will cancel eachother out, and produce a baseline pulse

45
Q

What happens when the surround area of an OFF cell is covered in 1/3 darkness, but the centre is still receiving light?

A

Will decr. the firing rate at the surround area is receiving less light, will not amplify as the centre is still illuminated (dampning the signal)

46
Q

What will happen when the surround area of an OFF cell is covered in 2/3 darkness, INCLUDING the centre?

A

Cell output will greatly increase, as the centre is no longer opposing the firing,

47
Q

What happens when the entire OFF cell is covered in darkness?

A

Cell output will return to a similar baseline, as there is still some firing as the centre is muted but there is less light to “activate” the surround

48
Q

Discuss the influence of contrast on GC cells

A

If a grey square is surrounded by white, it will look darker but if it is surrounded with black it will look lighter On the black background, cells would fire more, on the white background, cells would fire less

49
Q

The center receptive fields will emphasize __

A

Black/white edging

50
Q

(T/F) In Fovea acuity, there is a 1:1:1 ratio of PR:BPC:GC

A

T, this allows for increased acuity (everything picked up is transmitted)

51
Q

(T/F) In the periphery acuity, there is also a 1:1:1 ratio of PR:BPC:GC

A

F, there is a 6:4:1 ratio, as there is less acuity in the periphery

52
Q

(T/F) there are more PR in the fovea, as the ratio is higher

A

F, there are LESS PR in the fovea, and the ratio is lower (less is more)

53
Q

What is the first synaptic relay from the optic nerve?

A

To the dorsal lateral geniculate nucleus (LGN), passing through the optic chiasm (“splitting” of the input)

54
Q

Discuss the visual field

A

The visual field of the L eye overlaps with that of the right eye, this allows us to see the “big picture”.

  • Then, the information from the L and R are transmitted thru the optic nerve
  • The optic nerve is wired to “split” to the opposite sides of the brain thru the optic chiasm
  • Then, the information from the L eye reaches the R LGN, the R eye reaches the L LGN, and is then interpreted in the primary visual cortex on either side
55
Q

What is the general path of the visual pathway?

A

1) Lateral General Nucleus
2) Striate Cortex
3) Extrastriate Cortex

56
Q

Discuss what happens once the AP reaches the LGN

A

Sends output to VI (primary visual cortex) and V2 ( Visual association cortex)

57
Q

What are the three layers of the LGN? How many individual layers are their in total? (PMK)

A
  • Parvocellular (4 outer)
  • Magnocellular (2 inner)
  • Koniocellular
  • 6 in total
58
Q

In the LGN, the first two layers are closest to the _____

A

Inside of the brain, these are the magnocellular layers (labelled layers 1.2)

59
Q

What is the striate cortex?

A
  • The first cortical region involved in combining visual information from several sources
  • Receives information from LGN, and transmits info to the ES cortex
60
Q

How many layers in the SC?

A

6

61
Q

What do layers II, III and IVB project to in the SC?

A

To other cortical areas

62
Q

What do layer V cells project to in the SC?

A

The superior colliculus and pons

63
Q

What do layer VI cells project in the SC?

A

Back to the LGN

64
Q

What are the two layers in the SC involved in colour perception?

A

The paravocellular layer and koniocellular system

65
Q

In the SC, what does the paravocellular layer receive in terms of colour perception?

A

-Receives information only from red/green cones

66
Q

In the SC, what does the koniocellular system receive in terms of colour reception?

A

Will receive information from blue cones onlt

67
Q

What does the striate cortex do besides colour perception?

A

Helps with orientation and perception, where most neurons in the SC are sensitive to orientation

68
Q

How are neurons in the SC sensitive to orientation/perception?

A

Will only respond when lines are in a particular position, such as at a 90 degree angle

69
Q

What are the three types of orientation-sensitive neurons in the SC?

A

1) Simple
2) Complex
3) Hypercomplex

70
Q

Discuss the simple orientation-sensitive neurons in the SC

A

These cells have well defined inhibitory and excitatory regions, which when the line fits into either, it is turned on/off

71
Q

Discuss the complex orientation-sensitive neurons in the SC

A

Complex cells will be excited by all types of stimulus, inhib/excit regions are more arbitrary and there are so seperate on/off regions

72
Q

Discuss the hypercomplex orientation-sensitive neurons

A

inhibitory flanks on the ends of the receptive field, so that response increases with increasing bar length up to some limit, but then as the bar is made longer the response is inhibited.

73
Q

What is direction sensitivity?

A

Cells in the SC will respond to orientated lines/bars/edges moving in a preferred direction, but not in an opposing direction

74
Q

What is the extrastriate cortex responsible for?

A
  • Combining the information from the straite cortex to allow an indiviudual to perceive objects and entire visual scenes
  • Received info from lower regions and passes info to higher regions
75
Q

What are the two pathways of the ES?

A

1) Dorsal stream

2) Ventral stream

76
Q

What does the Dorsal stream process?

A

Where the object is located, including the speed and direction of movement (the WHERE)

77
Q

What does the ventral stream process?

A

What an object is and it’s colours (the WHAT)

78
Q

Which cells in the ES are involved n colour perception?

A
  • Parvocellular system

- Koniocellular system

79
Q

Discuss the parvocellular system and colour perception in the ES

A

-Shows high spatial resolution and low temporal resolutio

80
Q

Discuss the koniocellular system and colour perception in the ES

A

Does not provide information about fine details

81
Q

Discuss the magnocellular system and colour perception in the ES

A

Are colour blind

82
Q

(T/F) the dorsal stream receives mostly magnocellular input (light/dark contrast and movement)

A

True

83
Q

(TF) the ventral strea receives equal input from magnocellular, parvocellular and konicellular systems

A

T

84
Q

Parvocellular are ____ and ____ cones, Magnocellular are _____ and Koniocellular are ____ cones

A
  • Red, green
  • Colour blind
  • Blue
85
Q

Which stream of the EC is more associated with perception of form? Where does the perception of form begin?

A
  • Relayed to the subregions of the visual association cortex that constitute the ventral stream
  • It begin with the neurons that are in the SC senstitive to orientation and spatial frequencey
86
Q

What is visual agnosia?

A

-When there is damage to the EC, unable to identify common items by sight, although visual acuity remains

87
Q

What is a common symptom of visual agnosia?

A

prosopagnosia

-causes when the fusiform face area (FFA) which is devoted to facial recognition is altered

88
Q

The fusiform face area of the brain is most asociaated with the recognition of _____

A

Faces

89
Q

The extrastriate body area of the brain is most associated with the recognition of ____ and _____

A

Headless bodies and body parts

90
Q

What are the two types of vision which make up perception?

A
  • Monocular vision

- Binocular vision

91
Q

Discuss monocular vision

A

-Allows for perspectives, relies on relative retinal size and there is a loss of detail through the effects of atmospheric haze and appearance of movement

92
Q

What explains why we can see things further away, but with less details (i.e. rail road tracks rolling over a hill)

A

Monocular vision

93
Q

Discuss binocular vision

A

Vivid perception of depth thru the process of stereopsis

94
Q

What types of neurons are found in the SC? What do they mostly respond to?

A
  • Binocular vision neurons

- Retinal disparity

95
Q

Where are disparity sensitive neurons found? What are they associated with

A
  • Found in the dorsal stream (the where)

- Binocular vision

96
Q

What are the two areas of the brain in the EC are that associated with the perception of movement?

A
  • Area v5 (MV)

- Area MST

97
Q

Discuss Area v5 in the EC

A

-Contains neurons that respond to movement, where information is received from the SC and the superior colliculs

98
Q

Discuss the Area MST in the EC

A

Receive information about movement from V5, and helps analyze optic flow

99
Q

What will happen if there is bilateral damage to the V5?

A

Inability to perceive movement, known as akinetopsia

100
Q

(T/F) The MT/MST are located in the ventral stream

A

F, located in the dorsal stream

101
Q

What is found in the ventral stream?

A

LOC (lateral occipital complex) and FFA (Fusiform face area)

102
Q

Wha is LOC and FFA associated with? Where are they found?

A
  • Object and facial recognition

- In the ventral stream (the WHAT)

PSYC 211 (Behavioural Neuroscience) (4 decks)

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