Vision

Question 1

what do we see

Answer 1

The reflection of electromagnetic waves emitted by the sun; color is the absorption of all wavelenghts exept those

Question 2

optic nerves from the left and right eye partially cross at the …

Answer 2

optic chiasm

Question 3

rods

Answer 3

perception at very low levels of light

Question 4

cones

Answer 4

perception at a lot of light: colors and details

Question 5

difference rods and cones regarding photons

Answer 5

rods can be triggered by a single photon, cones need to absorb more photons

Question 6

fovea

Answer 6

Place on the retina where the image you focus on is projected to.

Question 7

hoe gaat het signaal vanaf retina naar optic nerve

Answer 7

photoreceptors -> 5 other cell layers: bipolar cells - ganglion cells -> via optic nerve that goes through the retina, creating a blind spot

Question 8

waar zijn de rods en waar zijn de cones veel

Answer 8

cones veel bij fovea, rods veel buiten de focea

Question 9

acuity

Answer 9

hoe scherp het is: hoogste bij de fovea, wordt minder hoe verder je er vanaf gaat

Question 10

je hebt alleen een duidelijk en kleurrijk beeld bij de fovea, de rest is wazig

Answer 10

maar dit zie je zelf niet zo!

Question 11

saccades

Answer 11

we constantly redirect our gaze (3/4x per seconde) -> niet random maar to salient events

Question 12

subcortical visual processing

Answer 12

Retina -> optic nerves -> optic chiasm -> optic tracts -> lateral geniculate nucleus (LGN) in thalamus -> optic radiations -> primary visual cortex

Question 13

LGN 2 components and what do they receive

Answer 13

• parvocellular system: from retinal parvocellular ganglion cells
• magnocellular system: from retinal magnocellular ganglion cells

Question 14

parvocellular

Answer 14

Small conduction velocity
-
Some are color sensitive
-
80% of retinal ganglion cells

Question 15

magnocellular

Answer 15

large receptive fields
(input from many
-
Fast conduction velocity
-
Info about motion and
depth to visual system
-
No color information
-
10% of retinal ganglion
cells

Question 16

opbouw van LGN

Answer 16

6 - L - P
5 - R - P
5 - L - P
3 - R - P
2 - R - M
1 - L - M

Question 17

optic radiation

Answer 17

axons from the LGN project to the primary visual cortex

Question 18

retinotopic organization at thalamus and V1

Answer 18

Objects that are close to each
other in the visual field (and
hence the retina), are also
represented close to each
other in the primary sensory
cortex.

Question 19

cortical magnification

Answer 19

the size of unit area in the retina =/= visual cortex representation -> fovea neemt veel meer ruimte in beslag.

Question 20

cortical modularity

Answer 20

cortical columns in primary sensory areas. (bv: ocular dominance colomns: reageren liever op een oog dan op de andere)

Question 21

receptive field

Answer 21

region in the retina that evokes a response in the neuron being measured.

Question 22

a neuron in V1 receives input from multiple LGN cells

Answer 22

oke

Question 23

LGN cell gets active when a light shines on it, but immediately inactive when a light shines beside it.

Answer 23

oke

Question 24

The further you go in the
visual stream, the more
complex the receptive fields!

Answer 24

(simple cells vs complex cells (grandmother cells))

Question 25

dorsal stream

Answer 25

where -> motion and spatial, to parietal

Question 26

ventral stream

Answer 26

what -> form and color, to temporal

Question 27

ezelsbruggetje voor streams

Answer 27

venTral - whaT - Temporal lobe

Question 28

visual processing properties

Answer 28

lightness/brightness color form depth motion

Question 29

Simultaneous lightness/brightness contrast phenomenon

Answer 29

patches have the same luminance but you experience them as different colours. - door lateral inhibition: patch with darker background will be perceived as lighter, due to contrast. patch with lighter background will be less active due to lateral inhibition. (light = inhibition of surrounding cells!) Maar... dit is niet helemaal zo, want het ligt ook vooral aan onze kennis van de wereld. Dus; door de inverse problem: many different sources can produce the image on our retina.

Question 30

3 qualities of color

Answer 30

- hue = color - brightness = fel - saturation = colourness (grey of meer kleur)

Question 31

verschillende cones

Answer 31

3! (short, medium and long wavelengths.)

Question 32

color contrast

Answer 32

patches with identical physical properties can be seen as very different colours.

Question 33

color constancy

Answer 33

patches with different physical properties can be seen as the same colour

Question 34

which area processes colour

Answer 34

V4

Question 35

damage to V4 leads to

Answer 35

cerebral achromaoopsia (alles in zwart wit)

Question 36

form

Answer 36

perception of line lengths, orientation and intersections

Question 37

Does activity in V1 correspond to the actual stimulus or the perceived stimulus?

Answer 37

No, the activation evoked by the stimulus corresponded to the subjective experience of the size, not to the actual size.

Question 38

monocular components

Answer 38

- size and depth relative - occlusion - motion parallax (ver gaat met je mee, dichtbij gaat er tegenin)

Question 39

binocular component

Answer 39

retinal disparity because our eyes are further apart -> creates a different picture

Question 40

binocular rivalry

Answer 40

each eye gets a completely different image. but it is not a combination between the two, but a continuous change between the two states!

Question 41

motion

Answer 41

processed in area V5 wss

Question 42

aperture problem

Answer 42

Many combinations of speed and direction can give rise to the sequence of images falling on the retina -> hoe???

Question 43

apparant motion

Answer 43

Two static stimuli that are presented in close succession create a sense of motion. Known in Gestalt psychology as the phi phenomenon.

Question 44

motion aftereffect

Answer 44

After staring at motion to a single direction, you can observe motion in the opposite direction when looking away from the motion (neural adaptation?)

Question 45

You don’t need visual input to get visual cortex activity! Visual imagery of an object suffices to recreate the activity pattern in the visual cortex that would be active when seeing the object.

Answer 45

bv bij denken aan stoel.

Question 46

retinal ganglion cells

Answer 46

in LGN!!! -> parvocellular and magnocellular

Question 47

volgorde outside eye

Answer 47

sclera -> choroid -> retina