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PSY280 > The eye and seeing > Flashcards

The eye and seeing Flashcards

1
Q

Sensory receptors

A
  1. Vision
  2. Hearing
  3. Smell
  4. Taste
  5. Tocuh
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2
Q

The neuron

A

A signal is received by dendrites
Information is set along the axon via an action potential until it reaches the terminal buttons

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2
Q

Neuronal communication (3 activities from any signal cell)

A
  1. Spontaneous firing: when the cell is not receiving any signal, still random potential
  2. Excitatory activity: increase in frequency of action potential (increases chances of action potential)
  3. Inhibitory activity: fewer action potential compared to spontaneous (decreases chances of action potential)
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3
Q

Synapse

A

small gap between the terminal buttons and (typically) dendrites

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4
Q

Y-shape neural processing

A

excitatory connection

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5
Q

Straight-line neural processing

A

Inhibitory connection

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6
Q

Neural processing

A

The modulation of the neural signal at the synapse allows communication between different neurons/interactions between different stimuli

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7
Q

Spare coding

A

smaller of neurons that respond to a stimulus; stimulus is still coding by located at the distribution

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8
Q

Population coding

A

more neurons show activity; determined by the activity across the cells

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9
Q

Behaviour of light (2 sources of light)

A
  1. Point source: light coming from one point (ex. the sun, light bulb)
  2. Diffuse illumination: light comes from everywhere (ex. light on a cloudy day, the light is coming from every direction because the clouds are covering certain sections)
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10
Q

Radiance

A

how much light coming off a source

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11
Q

Light can do 3 things when it comes in contact with a surface

A
  1. Transmission (ex. light goes through the object)
  2. Absoprtion
  3. Reflection (ex. mirror)
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12
Q

Illuminance

A

how much light is hitting the surface

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13
Q

Reflectance

A

the proportion of luminance compared to illuminantion

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13
Q

Luminance

A

how much light is being reflecting from a surface

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13
Q

Brightness

A

psychological judgement of radiance and/or luminance

Refers to the absolute amount of light from an object
Think of when you walk into a bright room

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14
Q

Lightness

A

psychological judgement of reflectance

Refers to the percentage of light reflected from an object
Think of the shade (light = more white)

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15
Q

Pupil

A

like camera aperture to control the amount of light entering the light

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15
Q

Pinhole camera

A

a. the image is smaller and inverted

b. the image is very faint

c. the results in a blurry image

d. add a lens, so each point is now focused and the image is harp; the image is still inverted and small, but it is clearer

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15
Q

Lens

A

can accommodate focusing on object at different distances

16
Q

Retina

A

where image is projected

17
Q

Anterior chamber

A

the front part of the eye between the cornea and the iris

18
Q

Cornea

A

hard structure outside of eye, to protect the eye; important for bending light

19
Q

Iris

A

gives eye colour, ring of muscles to help pupil change sides

20
Q

Posterior chamber

A

fluid, maintains pressure of eye

21
Q

Scieria

A

our of circle of the eye

22
Q

Optic disc

A

neurons leave the eye toward the brain; blood vessels in and out (blind spot is located) (no photoreceptors)

23
Q

The lens: accommodation

A

lens changing shape to focus on different objects

Goal is for light to come to a point on the retina

24
Q

Accommodation (thin lens)

A

Lens gets thinner to focus on far objects

Point that lens can no longer bring far objects into focus is called the far point

25
Q

Accommodation (thick lens)

A

Lens is thick to focus on near objects

Point that lens can no longer bring near objects into focus is called the near point

26
Q

Problem with accommodation (Myopia)

A

Myopia (nearsightedness)

The eyeball is too long or the lens is too thick

Negative lens diverges light allowing it to focus again on the retina

27
Q

Problem with accommodation (Hyperipia)

A

Hyperopia (farsightedness)

The eyeball is too short or the lens is not able to accommodate sufficiently

Positive lens converges the light allowing it to focus on the retina

28
Q

Problem with accommodation (Presbyopia)

A

Presbyopia (old vision)

The lens loses its ability to accommodate with age

Positive lens converges the light allowing it to focus on the retina

29
Q

Cones (cones = colours)

A

Photopigment: photopsins I, II, III (opsins + retinal)
Important for colour vision)
Makes up our photopic system
Used for vision in bright light
Important for visual acuity
Mostly located in fovea

29
Q

Rods

A

Not sensitive to colours
Makes up our scotopic system
Used for vision in dim light
Important for sensitivity to light
Mostly located in retinal periphery (none in fovea)

30
Q

Photoreceptors

A

connected to each other via horizontal cells

Horizontal cells are important for modifying the strength of neighbouring photoreceptors (essential for lateral inhibition)

31
Q

Bipolar cells can be categorized based on their size

A
  1. Diffuse bipolar cells are connected to many photoreceptors (usually connected to rods)
  2. Midget bipolar cells are only connected to one photoreceptor (usually connected to cones)
32
Q

Bipolar cells can be categorized based on their response to light

A

ON bipolar cells respond to a light signal (reduced activity from photoreceptors)

OFF bipolar cells respond to the absence of a light signal (increased activity from photoreceptors)

33
Q

Two types of Ganglion cells

A

P cells
- connected to cones via midget bipolar cells
- little convergence
- small receptive fields (little conversions, small # of cones that converge to P ganglia size)
- colour sensitivity

M cells
- connected to rods via diffuse bipolar cells
- lots of convergence
- large receptive fields
- colour insensitive

34
Q

Two systems for light and dark

A
  1. Rods –> diffuse bipolar cells –> M ganglion cells –> light sensitivity
  2. Cones –> midget bipolar cells –> P ganglion cells –> visual acuity and colour
35
Q

What is the output of an OFF bipolar cell that detects depolarization from s rod?

A

Depolarization

36
Q

Less sensitive

A

in bright light; more pigments bleached

37
Q

More sensitive

A

Dim light; fewer pigments bleached

38
Q

Cones are quick to what?

A

quick to adapt (regenerate), but never get very sensitive to light

39
Q

Rods are slow to adapt?

A

slow to adapt (regenerate), but are very sensitive to light

40
Q

Little patch of dark, light everywhere else

A

OFF ganglion cells

41
Q

Little patch on light, dark everywhere else

A

ON ganglion cells

42
Q

Antagonistic ganglion receptive fields

A

result of lateral inhibition from horizontal cells and writing with bipolar cells

Light in centre = excitatory
Light outside = inhibition

PSY280 (5 decks)

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