Vision Flashcards

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1
Q

Cornea

A

curved transparent external surface of eye, causes light to bend, no receptive field

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2
Q

Pupil

A

the Opening allows light to enter the eye, no receptive field

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3
Q

Iris-circular muscle

A

controls pupil size, no receptive field

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4
Q

lens

A

focuses the light of the retina, no receptive field

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5
Q

Ciliary muscles

A

control lens shape

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6
Q

Accomadation

A

process of lens changing to focus on different objects

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7
Q

Extraocular muscles

A

control eye movement

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8
Q

Retina

A

layers of cells at the back of the eye,
rods and cones(Spot of light)
bipolar cells(Concentric RF)
ganglion cells(Concentric RF)
axons of ganglion cells form the optic nerve

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9
Q

Rods and Cones(photoreceptors)

A

transduce light, spot of light

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10
Q

Two functional systems of Retina

A

Scotopic system, Photopic system

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11
Q

Scotopic System

A

functions in dim light, one type of receptor(rods)

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12
Q

Photopic system

A

functions in brighter light, three types of (cone) receptors

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13
Q

photopigment(captures light) in rods

A

rhodopsin

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14
Q

rhodopsin

A

composed of retinal and opsin

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15
Q

Photoreceptors Hyperpolarization

A
  1. light activates rhodopsin
  2. retinal dissociates from opsin
  3. opsin binds G protein
  4. G protein transforms 2nd messenger
  5. blocking Na+ channels causing hyperpolarization(and less glutamate release)
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16
Q

Cones Function

A

similar to rods but have three different types of opsin

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17
Q

on center bipolar cells

A

hyperpolarize in
response to glutamate from photoreceptors,
want light, meaning less glutamate

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18
Q

off center bipolar cells

A

depolarize in
response to glutamate,
want less light meaning more glutamate

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19
Q

photoreceptors and bipolar neurons in response to Dim light

A

lots of glutamate
off center has a large response,
on center has a low repsonse

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20
Q

photoreceptors and bipolar neurons respond to brighter light

A

less glutamate,
on center has a high repsonse
off center has a low response

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21
Q

on center bipolar cells excite

A

on center ganglion cells

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22
Q

off center bipolar cells excite

A

off center ganglion cells

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23
Q

fovea

A

depression in central region of retina best acuity

24
Q

why does fovea have best acuity

A

no cell layers
the high density of cones
low cone-to-ganglion ratio
large amount of V1 devoted to fovea

25
Q

Visual pathway

A

ganglion cells in retina
-optic nerve
-optic chiasm
-optic tract
lateral geniculate(thalamus(brain))
-optic radiations
occipital(or striate) ctx
extrastriate ctx

26
Q

Receptive Field

A

stimuli in the environment (visual space) that increase or decrease the cells response

27
Q

bipolar and ganglion cells in retina have

A

Concentric Receptive fields

28
Q

on center/off surround

A

cell is excited by spot of light in its center

29
Q

off-center/on surround

A

cell is excited by spot of dark in its center

30
Q

Concentric receptive fields

A

response to light is opposite in center vs surround

31
Q

Ganglion cell types

A

off center and on center, M cell(movement) and P cells(Pretty), concentric

32
Q

M cells

A

larger RF
more sensitive to low-contrast stimuli
stimulus movement

33
Q

P cells

A

the opposite of M cells
sensitive to form and fine detail
sensitive to wavelength
have color opponent property, center and surround are excited by different colors
have spectral opponency

34
Q

Lateral Geniculate nucleus

A

concentric RF
Layer of cells
-parvocelluar neurons
-magnocelluar
Magnocellular and parvocellular layers reflect properties of input M cell and P cells

35
Q

Parvocellular

A

receive info from P cell
spectral opponency

36
Q

Magnocelllular

A

receive info from M cells

37
Q

LGN projects to

A

Layer IV of visual of cortex by optic radiation(Axon RF)

38
Q

Layer IV

A

left and right eye projections are laid out as a series of alternating bonds called ocular dominance columns

39
Q

simple cortical cells

A

Respond best to an edge or bar of a particular width, orientation, and location

40
Q

complex cortical cells

A

Respond to the bar of particular width and orientation anywhere in the visual field

41
Q

two major systems of cortical visual areas

A

ventral processing stream
dorsal processing stream

42
Q

Dorsal Processing Stream

A

where
location of objects
perception of place, depth, and movement
extension of magnocellular pathway(LGN)
MT(V5), MST, and other dorsal areas

43
Q

Ventral Processing Stream

A

what
visual identification of objects
analysis of form and color
extension of the parvocellular pathway
V4, IT, and other ventral areas

44
Q

Dorsal processing stream

A

V1—> V2—>V3—>MT(V5)—>MST—>other dorsal areas

45
Q

Ventral Processing Stream

A

V1—> V2—> V4—> IT—> other ventral areas

46
Q

V2

A

illusory contours(triangles)

47
Q

MT

A

Perception of motion

48
Q

V4

A

Intermediate complexity, ex. radial stimuli, ceiling fan

49
Q

IT

A

complex forms and pattern recognition(faces)

50
Q

cones for trichromatic theory

A

doesn’t respond to a specific wavelength
responds to a range of wavelengths and peaks at a particular wavelength
Small medium and Long

51
Q

spectral opponency

A

One color excites the center; different color excites the surround
ex. Long wavelength excites, Medium wavelength inhibits

52
Q

optic nerve

A

one eye two fields(left and right)

53
Q

optic chiasm

A

two eyes two fields

54
Q

optic tract

A

one eye, one field

55
Q

spectral oppencey

A