Brainscape's Knowledge GenomeTM

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


See full index

C1 Modules > Visual pathway > Flashcards

Visual pathway Flashcards

1
Q

What is 50% of the cerebral cortex?

A

Visual

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

What are examples of the large no. of submodalities in vision?

A
  1. Colour
  2. Depth
  3. Motion
  4. Spatial localisation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the properties of visual acuity?

A
  1. Minimum separable images
  2. Depends on cone density in photopic vision
  3. Falls of with increasing eccentricity from fovea
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is used for acuity in central vision?

A

Letter or other symbol

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

What is most commonly used to assess peripheral vision?

A

Sensitivity to spots of light

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

Define retinal eccentricity?

A

When objects are projected directly onto fovea are the sharpest

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

How is visual acuity measured?

A

Smallest letters that can be distinguished on a chart and is governed by anatomical spacing of mosaic of sensory elements on retina

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

What is found only in the fovea?

A

Cone photoreceptors

Photoreceptors that deal with higher light levels, non-functioning at low light level - subserve colour

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

What is found at the periphery retina?

A
  1. Cones

2. Rods taking over at low light levels

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

What does visual acuity use?

A

Fovea

Width of 2 foveal cones = 1 arc minute

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

What is 360 degrees in vision?

A

Entire visual world around the subject

Divide into 60 arc/minute

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

What is the resolution limit of visual acuity?

A

60c/deg or a line resolution of 30 arc seconds

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

What is hyperacuity measured in and what does it detect?

A

3 arc seconds

Detect displacement of 2 light: Higher processing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Define visual acuity

A

The ability to read a standard test pattern at a certain distance, usually measured in terms of a ratio to ‘‘normal’’ vision

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

What is the test of foveal vision based on?

A

Gaps that are used by humans to identify those letters

  1. same no. of letters on each line
  2. Same level of difficulty
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Where is fovea located?

A

Optical centre of eye

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

What is found at the optic nerve?

A

Physiological blindspot

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

What is not present in the fovea?

A

Rods

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

What is Perimetry?

A

A test of the entire visual field

Central 30 degrees

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

What does perimetry measure?

A

All areas of your eyesight, including your side, or peripheral vision

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

Where are Rods and cones found?

A

Rods: Periphery of the eye
Cones: Throughout the fovea [high concentration]

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

What happens at high light levels?

A

Rods doesn’t function

23
Q

What happens at low light levels?

A

Cones doesnt function

24
Q

What does numbers in perimetry represent?

A

Threshold detecting a bright spot on the background

25
Q

What is visual world created from?

A

Electromagnetic radiation falling on the retina

26
Q

What is Kanizsa triangle?

A

illusory contours
A white equilateral triangle can be clearly be perceived even though there are no explicit lines or enclosed spaces to indicate such a triangle

27
Q

What does visual perception do?

A

Takes the information and does Bayesian probability prediction as to find the appropriate physical explanation for the image that is falling on the retina

28
Q

What is perception thought to be?

A

Dynamic

29
Q

What is filling in?

A

An empty region of visual space appears to be filled with colour, brightness or texture of its surround

30
Q

What is the brain capable of filling in?

A

The blindspot, borders, surfaces and objects

31
Q

What is fading?

A

When one fixates on a particular point for even a short period of time, an unchanging stimulus away from the fixation point will fade away and dissapear [peripheral fading]

32
Q

What are photoreceptors?

A

Analysis of colour

33
Q

What are the spectral responsitivites of 3 cone types?

A
  1. Blue, green or red

2. Short, medium and long wavelength photoreceptors

34
Q

What can we not discriminate?

A

Any colour that cannot be created by different outputs from those 3 cone types

35
Q

Why does retina have to be transparent?

A

Photoreceptors are at the back of retina therefore requires high energy requirements

36
Q

What varies with eccentricity?

A

Dendritic spread and cell body size and cell type

37
Q

What is the basic arrangement of RGC called?

A

Centre-surround

simplest form of receptive field

38
Q

What are all RGC divided into?

A

50% on centre and 50% off centre

39
Q

What is on-centre?

A

Light falling on centre

40
Q

What is off-centre?

A

Light falling on surrounding regions

41
Q

What is magno, parvo and Konzo?

A

A neuron with a small cell body that is located in koniocellular layer of LGN in primates, including humans

42
Q

What does magno subserve?

A

Detection of high temporal frequencies - motion high contrast sensitivity
Chromatic information does not contribute to hue discrimination

43
Q

What does parvo subserve?

A

slower temporal response - low contrast sensitivity but with spectral opponency
High acuity foveal cone system

44
Q

What does konzo subserve?

A

Sluggish temporal response - variable morphology and response function

coneo-cellular pathway

45
Q

What are the properties of magnocellular system?

A

Large RGCs include parasol ganglion cells
30 micrometre dendritic spread at Fovea
axonal diamater large
10% total population
projects to layer 4c alpha of V1
high contrast sensitivity
Chromatic information present but would not contribute to hue discrimination

46
Q

What are the properties of Parvocellular system?

A

Small RGC include foveal midget ganglion cells
5-10 micrometre dendritic spread at fovea
Axonal diameter small
80% total population
Projects to layer 4cB ‘interblob’ and ‘blob’ regions of VI
Low contrast sensitivity
spectral opponency

47
Q

What is the property of koniocellular system?

A

Small dendritic spread, varied morphology
Axonal diameter small
10% total population
Projects to layer interlaminar region of LGN+ to midbrain
Projects to layer 3 and ‘blob’ regions of VI
Intermediate constrast sensitivity
Variable spectral opponency

48
Q

What are the properties of Intrinsically photosensitive RGCs?

A 
3rd photoreceptor
Large dendritic spread
Axonal diameter small
1% total population
Project to midbrain
light sensors
Input from rods and cones aswell as intrinsic sensitivity to light
49
Q

What is the role of IPRGCs?

A

Circadian rhythms, pupil light reflex

50
Q

What is optic nerve surrounded by?

A

cranial meninges

51
Q

Chiasm

A

All information coming from one hemi-field is going to contralateral side of brain

52
Q

How are magnocellular and parvocellular arranged in the optic nerve?

A

Magnocellular are ventral
Parvocellular are dorsal that go into LGN also crossing over where fibres are coming from retina - move to opposite optic tract in chiasm

53
Q

What does visual input remain?

A

Monocular

54
Q

How were blobs discovered?

A

Cytochrome oxidase staining of the visual cortex

higher metabolic activity

C1 Modules (20 decks)

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