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Biological Psychology > vision > Flashcards

vision Flashcards

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1
Q

light

A

form of electromagnetic radiation

what our visual system lets us see

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2
Q

wavelength

A

distance between peaks

in nanometers

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3
Q

visual fields

A

all you survey without head or eye movement

each eye has its own visual fields, they overlap to some extent, not so much laterally

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4
Q

acuity

A

sharpness of visions

visual system’s ability to resolve fine detail

sharpest as the center of the visual field - falls off toward the periphery

best in fovea

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5
Q

fovea

A

place in central vision where greatest acuity is found

high density of cones

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6
Q

photoreceptors

A

rods and cones

basic light receiving units that line the back of the eye

stimulate other neurons whose axons form the optic nerve which exits the eyeball

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7
Q

blind spot

A

in the visual field of each eye

corresponds to the location where axons of the optic nerve exit the eyeball (optic disk)

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8
Q

optic disks

A

where blood vessels and ganglion axons leave the eye

no photoreceptors

meaning there is a blind spot

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9
Q

brightness

A

(value)

an axis from light to dark

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10
Q

hue

A

an axis through blue, green, yellow, orange red and the variations in between

the rainbow

colours

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11
Q

explain transduction in rods

A

light particles are detected in the disks

photo strikes photopigment on disk membrane

rhodopsin splits when hit by a photon into retinal and opsin to capture energy.

this activates a 2nd messenger pathway

cGMP

sodium channels close (normally open when + ions come, but they are not coming)

graded potential causes hyperpolarization which cuses the cell to release less NT

NT glutamate is released stimulating bipolar cell

hyperpolarization reduces transmitter release, signaling a change in light

graded potential goes down bipolar cell (passive) causeing depolarization

NT is released, stimulating ganglion cell

AP propagates down ganglion cell and message is sent to brain

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12
Q

what type of receptor fields do bipolar and ganglion cells have

A

donut like receptive field

  • light falling on whole receptive field exhibits a weak response (center and surround pretty much cancell
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13
Q

off center bipolar cells

A

glutamate is excitatory

shining light on cell’s receptive field would inhibit

turning off light excites it

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14
Q

lateral inhibition

A

interconnected neurons inhibit their neighbours, produces contrast. at the edges of regions

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15
Q

Ca++ currents

A

are altered to change responsiveness

mechanism is unknown

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16
Q

fusion of retinal and opsin

A

back into pigment is slow - at high intensities, less and less pigment is available

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16
Q

enzyme phosphodiesterase

A

rate-limiting in the 2nd-messeneger system that open sodium channels

there is limited phosphodiesterase available and ever more scarce at higher and higher intensities

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16
Q

optic nerve

A

axons from ganglion cells

travels to the base of the brain

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17
Q

optic chiasm

A

axons from “nasal hermiretina” cross over to the other side of brain

info from left part of both retinas goes to the left hemisphere and vice versa

left hemiretina receives image from the right visual field

point where two optic nerves cross the midline

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17
Q

optic tract

A

radiation of fibres into the brain from optic chiasm

radiate into the base of the brain

after passing optic chiasm

minority of axons here send info to superior colliculus for rapid movements of the eye

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18
Q

lateral geniculate nucleus

A

visual part of the thalamus

relay system

where most optic nerve tracts terminate

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19
Q

occipital cortex

A

at back of brain

striate cortex

inputs from both eyes converge to give binocular vision (depth perception), among other things

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20
Q

retinotopic organization

A

map of the retina maintained at all levels and projected onto visual cortex (upside and background)

most devoted to fovea - makes for increased acuity

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21
Q

superior colliculus

A

spatial maps and eye movements

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22
Q

saturation

A

amount of pigment a given hux

rich - pale

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22
Q

trichromatic hypothesis

A

the theory that there are three different types of cones (red, blue, green), each excited by a different region of the spectrum and each having a different pathway to the brain

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22
Q

opponent - process hypothesis

A

different systems produce opposite responses to light of different wavelengths

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22
Q

motion

A

movement of the eye is controlled by extra-ocular muscles

visual systems are especially tuned to motion

movement in peripheral vision captures attention and shifts gaze

evolutionary significance ie/ bullet time

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22
Q

subjective brightness

A

the brightness you perceive

personal experience

visual system opperating at only 1/5th of total brightness range

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23
Q

cornea

A

transparent outer layer of eye

curvature is fixed

bends light rays

primarily responsible for forming the image on the retina

refracts light rays

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23
Q

myopia

A

eyeball too long

images focus in front of the retina

image that actually reaches the retina is blurred

nearsightedness

difficulty seeing distant objects

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23
Q

accommodation

A

muscle process of focusing the eye

like a camera lens

lens must be shapes correctly so that the image of an object at a given distance is focused on the retina
- lens round for close up, lens flattens for far away

inaccurate accomation = poor focus = glasses

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23
Q

refraction

A

the bending of light rays by a change in density of a medium

happens from cornea to lens

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23
Q

lens

A

helps us focus the image on the retina

changes its shape to fine-tune the image on the retina

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23
Q

photoreceptor adaptation

A

tendency of rods and cones to adjust their light sensitivity to match current levels of illumination

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23
Q

range fractionalization

A

handling of different intensities low threshold in rods and high thresholds in cones

scoptic vision in low light, phototopic in bright light

cannot have an extensive range fractionalization, bc we can not afford to have large numbers of receptors inactive under various lighting conditions

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23
Q

iris

A

light control

coloured part

opens and closes in response to the amount of light entering the eye

controlled by the brainstem

23
Q

retina

A

receptor surface inside the eye that contains photoreceptors and other neurons

turns light into a neural signal

23
Q

ciliary muscles

A

around iris

pupil dilates when contracted

pupil relaxs - opens

changes lens shape

24
Q

superior/ inferior rectis

A

up and down movement

24
Q

constriction of pupils

A

in bright light

controlled by parasympathetic

25
Q

dilation of pupils

A

controlled by sympathetic division

26
Q

superior and inferior oblique

A

rotational movement

26
Q

medial and lateral rectus

A

side to side movement

27
Q

oculomotor nerve

A

everything except superior oblique and lateral rectus

28
Q

trochlear nerve

A

superior oblique

29
Q

abducens nerve

A

lateral rectus

30
Q

ganglion cell

A

AP

one million

connect with bipolar cells

any cells in retina whose axon forms the optic nerve

30
Q

tapetum ledum

A

in many animals (not human)

an eye flash

goes bright when flashlight shines in dark

reflective to the light

31
Q

amacrine cell

A

AP

contact with bipolar and ganglion cells

significant in inhibatory interactions in the retina

provide lateral communication with neighbouring retina

32
Q

horizontal cell

A

graded

make contact with photoreceptors and bipolar cells

provide lateral communication with neighbouring retina

33
Q

bipolar cell

A

graded

photoreceptor cells release here

interneuron

receives from photoreceptors and passes to ganglion cells

34
Q

rod cell

A

graded

35
Q

convergence

A

several receptors connect to individual bipolar cells

numerous bipolar cells may connect to a single ganglion cell

greater in rods than in cones

36
Q

scotopic system

A

works in dim light - where it is most sensitive

insensitive to colour

rods

lower acuity

away from fovea

black and white

lots of convergence

37
Q

photopic system

A

needs more light

has a higher threshold

cones

colour - sensitivity to wavelengths

high acuity

near fovea

ganglion cells report from a single cone

38
Q

suprachiasmatic nucleus

A

biological rhythms

39
Q

scotoma

A

a spot where nothing can be perceived

a region of blindness within the usual visual fields caused by injury to visual pathway or brain

40
Q

retinohypothalamic tract

A

tracks light to know when day/night is

41
Q

parvo system

A

four outer layers of the LGN contain small parvocellular neurons

relatively small receptive fields

donut shaped receptive fields

sensitive to wavelength (colour)

cone based

receive axons from “P” type retinal ganglion cells, which are smaller, like high contract, notice colour and fire with a tonic (firing at all times just increased or increased) background rate

42
Q

magno system

A

inner 2 layers of the LGN contain large magnocellular neurons

larger receptive fields

rods

most are not sensitive to wavelength

receive axons from M type retinal ganglion cells, which are larger, detect low contrast, do not notice colour, anre fire only transiently. they have large extra speedy axons

sensitive to low intensity

43
Q

what are the four classes of V1 cells

A

simple
complex
hypercomplex 1 and 2

44
Q

simple cells

A

respond and have more APs where there is a bar or edge of a specific width, specific orientation, and specific location in the visual field

45
Q

complex cells

A

have elongated receptive fields

like a bard or edge (would be long) of a specific orientation and size but could be at a number of different locations in the visual field

46
Q

hypercomplex 1 cell

A

particular emphasis on bar length

47
Q

hypercomplex 2 cell

A

like particular angles of intersection of lines

48
Q

spatial frequency analysis

A

visual patterns are not perceived as a built up complex of edges and continuous after all

instead cortical cells respond to various spatial frequencies that make up an image

any image can be broken down into a mathematical sum of large number of alternating light and dark grids (fourier analysis)

broad dark areas in a pic have low spatial frequency

areas with fine detail show rapid alterations from light to dark and have high spatial frequency

49
Q

cortical blindness

A

lesions in V1

a place in the visual field where nothing is perceived

50
Q

blindsight

A

permit some perception of movement

seperate visual systems for seeing things and moving through the world (knowing a stimulus is present)

51
Q

ocular dominance columns

A

regualr spaced along the V1 cortex and extending inwards in a column, are found patches of cells that respond to inputs from either the left or right eye

52
Q

orientation columns

A

within ODCs

cells within each orientation column respond best to stimuli with a particular angular orientation

53
Q

Area V2

A

receives input from V1

has more complex receptive fields

is active in providing contour inferences, may be important in disembedding stimuli (discriminating which parts of the visual scene make up complex items)

has complex interations with V4

passes info to the temporal lobe where object recognition

54
Q

prosopagnosia

A

condition in which there is a selective loss of ability to identify faces

lesions are large and bilateral and and believed to involve the systems that receive input from V2

55
Q

area V3

A

not well understood

seems to be involved with dynamic form - ability to know it is the same object even though it is changed from when moving
- slightly different forms of the same thing, ie/ person walking, ball being thrown

provides this sort of perceptual lock

56
Q

s cones

A

peak response to blue (short wavelength) but all respond to other shorter and longer wavelengths

fewer of them

acuity is much lower

420nm

57
Q

M cones

A

have peak responses to medium wavelengths, roughly green but overlaps

530 nm

58
Q

L cones

A

have peak repsonses to long wavelengths around yellow but overlaps

560nm

59
Q

blue wavelength

A

short and high frequency

60
Q

red wavelength

A

long and short frequency

61
Q

spectral opponency in LGN

A

neuron that has opposite firing responses to different regions of the spectrum

l, m and s info is fed to retinal ganglion cells and passed to the LGN

62
Q

+L/-M

A

yields an orange-red peak (650) nm

63
Q

+M/-L

A

yields a blue-green peak (500nm)

64
Q

+(L+M)/-S

A

gives far red peak (700nm)

65
Q

+S/-(L+M)

A

gives a blue peak (450nm)

66
Q

Area V5

A

in medial temporal area

responds to moving stimuli (own motion, eye motion, or head motion)

67
Q

parvo in higher levels

A

implicated in colour, form and recognition

68
Q

magno in higher levels

A

implicated in depth and object movement

69
Q

dorsal

A

object localization and body movements towards things in the environment (like magno)

where

70
Q

ventral

A

object recognition (like parvo)

what

71
Q

optic ataxia

A

damage to the dorsal parietal cortex

difficulty using vision to reach/ grasp for objects

72
Q

amblyopia

A

acuity is poor in one eye, even tho the other eye is normal

caused by lazy eye, misalignment of the two eyes

Biological Psychology (6 decks)

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