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Behavioural Neuroscience > Lecture 9 - Vision > Flashcards

Lecture 9 - Vision Flashcards

1
Q

Sensation

A

Cells of nervous system detect stimuli in environ. (Light, sound, heat…)
-> transduce signals into change in membrane potential & NT release

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2
Q

Perception

A

Conscious experience & interpretation of sensory info

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3
Q

Sensory neurons (Sensory receptors)

A

Specialized neurons: Detect specific category of physical events

Receptor proteins: sensitive to specific sensory stimuli, specific features of extracellular environ.

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4
Q

Sensory receptors sensitive to:

A

1) Presence of specific molecules (via chem interactions)
-smell, taste, nausea, pain
2) Physical Pressure
-touch, stretch, vibration, acceleration, gravity, balance, hearing, thirst, pain
3) Temperature
-heat, cold, pain
4) pH (acidity, basicity)
-sour taste, suffocation, pain
5) Electromagnetic radiation (light)
-vision

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5
Q

Some non-human animals - other senses

A

Ability to detect electrical & magnetic fields, humidity, water pressure

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6
Q

Sensory transduction

A

NT release when there’s no action potential:

Some sensory neurons not have axons or action potential, all release NT

Small cells: release NT in graded fashion, depending on membrane potential
->More depolarized, More NT released

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7
Q

Neural Transduction of Light (Opsins)

A

Opsins: Receptor proteins sensitive to light
-> 4 diff types of opsins to detect light

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8
Q

4 Opsin proteins for Vision

A

1) Rhodopsin
2) Red cone opsin
3) Green cone opsin
4) Blue cone opsin

Each photoreceptor cell in eye contain only 1 of these opsins, so 4 diff types of photoreceptor cells

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9
Q

4 Photoreceptor cells (express 4 opsins)

A

1) Rod cells -> rhodopsin
2) Red cone cells -> red cone opsin
3) Green cone cells -> green cone opsin
4) Blue cone cells -> blue cone opsin

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10
Q

2 Configurations of retinal

A

See pic

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11
Q

Visible light

A

Electromagnetic energy with wavelength between 380 & 760 nm (detect with 4 photoreceptor cells)

See pic

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12
Q

Rod cells (1 kind)

A

Very sensitive to all visible light

(See pic)

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13
Q

Cone cells (3 kinds)

A

Not particularly sensitive to light

3 kinds: each sensitive to diff wavelengths -> encode colour vision

(See pic)

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14
Q

Trichromatic Coding (cone photoreceptors)

A

3 cone opsins sensitive to diff wavelengths of light

1) Blue cone opsins: short wavelengths
2) Green cone opsins: medium wavelengths
3) Red cone opsins: long wavelengths

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15
Q

Colour perception

A

Function of relative rates of activity in 3 types of cone cells
(colour discriminated by ratio of activity across 3)

(See graph pic)

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16
Q

Activation of cone cell

A

Depends on:
1) Wavelength of light
2) Intensity (amount) of light

Green opsin most sensitive to light, so green colour light shines brightest out of three at same intensity

(See 2 pics)

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17
Q

Additive vs Subtractive Color: Light vs Paint

A

See pic

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18
Q

Perceptual Dimensions of Colour & Light

A

3 dimensions:
1) Brightness - Intensity (luminance, amount)
2) Saturation - Purity (composite wavelengths)
3) Hue - Dominant wavelength (colour)

(See pic)

19
Q

If Brightness 0%

A

Image is Black
Hue & Saturation have no impact

20
Q

If Saturation 0%

A

Image is Black & White, cuz
Middle of colour cone, where no colour (equal contribution from all wavelengths)

21
Q

Colour vision deficiency

A

1) Protanopia (no red cone)
2) Deuteranopia (no green cone)
3) Tritanopia (no blue cone)

(See pic)

Achromatopsia: True colour blindness (mutations in G protein signaling cascade) -signaling cascade similar in all cone cells

22
Q

Cornea

A

Outer, front layer of eye
-Focuses incoming light a fixed amount

23
Q

Iris

A

Pigmented ring of muscles

24
Q

Lens

A

Several transparent layers

25
Q

Accommodation

A

Shape of lens changes to allow eye to focus

26
Q

Pupil

A

Opening in the iris
-> Regulates amount of light entering eye

27
Q

Sclera

A

Opaque
-> does not permit entry of light

28
Q

Conjunctiva

A

Mucous membranes that line eyelid

29
Q

Retina

A

Interior lining (furthest back) of eye
-> contains photoreceptor cells (Rod or cone cells in humans)

30
Q

Vitreous humour

A

Clear, gelatinous fluid in eye
-> light crosses here after passing through lens

31
Q

Fovea

A

Central region of retina
-> very little compression of visual info
-> highest visual acuity

32
Q

Optic disk

A

Site of blind spot
-> point where optic nerve exits through back of eye (no receptors)

When close left eye and look at + with right eye, green dot to the right disappears at 20 min from paper (image is in blind spot)
-> See pic

33
Q

Anatomy of eye

A

See 2 pics

34
Q

Fovea & Periphery of retina

A

Foveal vision: Sensitive to detail & colour

Peripheral vision: Sensitive to dim light

(See pic for more details)

35
Q

Cone Photoreceptors

A

1) Most prevalent in central retina; found in fovea
2) Sensitive to moderate-to-high levels of light
3) Provide info about hue
4) Provide excellent acuity

36
Q

Rod Photoreceptors

A

1) Most prevalent in peripheral retina; not found in fovea
2) Sensitive to low levels of light
3) Provide only monochromatic info
4) Provide poor acuity

37
Q

Peripheral Vision

A

Low Spatial Frequency:

Image deficient in high frequency info -> unfocused but make out form

Poor visual acuity, cuz Rod cells mediate light perception

(High visual acuity: Fovea, cuz cone cells)

38
Q

Saccadic movements

A

Rapid, jerky shifts in gaze from one point to another (scanning scenes)

39
Q

Pursuit movements

A

Maintain image of moving object

40
Q

Eyes suspended in orbits

A

Bony sockets in front of skull

41
Q

6 extraocular muscles

A

Attached to sclera (tough, outer white of eye
-> Move eye around & hold it in place

(See pic)

42
Q

Photoreceptor cells

A

Neurons responsible for transduction of light, project to bipolar cells.

43
Q

Bipolar cells

A

Neurons relay info from photoreceptor cells to ganglion cells.

44
Q

Ganglion cells

A

Behavioural Neuroscience (5 decks)

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