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Biological Psychology > vision > Flashcards

vision Flashcards

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
saturation
amount of pigment a given hux rich - pale
22
trichromatic hypothesis
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
22
opponent - process hypothesis
different systems produce opposite responses to light of different wavelengths
22
motion
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
22
subjective brightness
the brightness you perceive personal experience visual system opperating at only 1/5th of total brightness range
23
cornea
transparent outer layer of eye curvature is fixed bends light rays primarily responsible for forming the image on the retina refracts light rays
23
myopia
eyeball too long images focus in front of the retina image that actually reaches the retina is blurred nearsightedness difficulty seeing distant objects
23
accommodation
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
23
refraction
the bending of light rays by a change in density of a medium happens from cornea to lens
23
lens
helps us focus the image on the retina changes its shape to fine-tune the image on the retina
23
photoreceptor adaptation
tendency of rods and cones to adjust their light sensitivity to match current levels of illumination
23
range fractionalization
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
23
iris
light control coloured part opens and closes in response to the amount of light entering the eye controlled by the brainstem
23
retina
receptor surface inside the eye that contains photoreceptors and other neurons turns light into a neural signal
23
ciliary muscles
around iris pupil dilates when contracted pupil relaxs - opens changes lens shape
24
superior/ inferior rectis
up and down movement
24
constriction of pupils
in bright light controlled by parasympathetic
25
dilation of pupils
controlled by sympathetic division
26
superior and inferior oblique
rotational movement
26
medial and lateral rectus
side to side movement
27
oculomotor nerve
everything except superior oblique and lateral rectus
28
trochlear nerve
superior oblique
29
abducens nerve
lateral rectus
30
ganglion cell
AP one million connect with bipolar cells any cells in retina whose axon forms the optic nerve
30
tapetum ledum
in many animals (not human) an eye flash goes bright when flashlight shines in dark reflective to the light
31
amacrine cell
AP contact with bipolar and ganglion cells significant in inhibatory interactions in the retina provide lateral communication with neighbouring retina
32
horizontal cell
graded make contact with photoreceptors and bipolar cells provide lateral communication with neighbouring retina
33
bipolar cell
graded photoreceptor cells release here interneuron receives from photoreceptors and passes to ganglion cells
34
rod cell
graded
35
convergence
several receptors connect to individual bipolar cells numerous bipolar cells may connect to a single ganglion cell greater in rods than in cones
36
scotopic system
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
photopic system
needs more light has a higher threshold cones colour - sensitivity to wavelengths high acuity near fovea ganglion cells report from a single cone
38
suprachiasmatic nucleus
biological rhythms
39
scotoma
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
retinohypothalamic tract
tracks light to know when day/night is
41
parvo system
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
magno system
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
what are the four classes of V1 cells
simple complex hypercomplex 1 and 2
44
simple cells
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
complex cells
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
hypercomplex 1 cell
particular emphasis on bar length
47
hypercomplex 2 cell
like particular angles of intersection of lines
48
spatial frequency analysis
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
cortical blindness
lesions in V1 a place in the visual field where nothing is perceived
50
blindsight
permit some perception of movement seperate visual systems for seeing things and moving through the world (knowing a stimulus is present)
51
ocular dominance columns
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
orientation columns
within ODCs cells within each orientation column respond best to stimuli with a particular angular orientation
53
Area V2
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
prosopagnosia
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
area V3
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
s cones
peak response to blue (short wavelength) but all respond to other shorter and longer wavelengths fewer of them acuity is much lower 420nm
57
M cones
have peak responses to medium wavelengths, roughly green but overlaps 530 nm
58
L cones
have peak repsonses to long wavelengths around yellow but overlaps 560nm
59
blue wavelength
short and high frequency
60
red wavelength
long and short frequency
61
spectral opponency in LGN
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
+L/-M
yields an orange-red peak (650) nm
63
+M/-L
yields a blue-green peak (500nm)
64
+(L+M)/-S
gives far red peak (700nm)
65
+S/-(L+M)
gives a blue peak (450nm)
66
Area V5
in medial temporal area responds to moving stimuli (own motion, eye motion, or head motion)
67
parvo in higher levels
implicated in colour, form and recognition
68
magno in higher levels
implicated in depth and object movement
69
dorsal
object localization and body movements towards things in the environment (like magno) where
70
ventral
object recognition (like parvo) what
71
optic ataxia
damage to the dorsal parietal cortex difficulty using vision to reach/ grasp for objects
72
amblyopia
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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