Vision

Question 1

what is meant by retinotopic

Answer 1

the spatial layout of the retina is preserved in the brain. nearby cells in retina connect nearby cells in visual cortex - forming a map

Question 2

what is the primary function of V1 (primary visual cortex)

Answer 2

basic feature detection (orientation, motion, edges)

Question 3

is v1 retinotopic

Answer 3

yes

Question 4

what did hubel and Wiesel find about v1

Answer 4

cells in v1 respond to specific orientations and directions of stimuli

Question 5

what is a hyper-column in v1

Answer 5

a group of columns that represents all orientations for a particular area of the retina,

Question 6

where is the v1

Answer 6

occipital lobe

Question 7

how are orientation-sensitive cells organised in v1

Answer 7

arranged in columns , each column contains cells that prefer a specific orientation

Question 8

what are ocular dominance columns

Answer 8

columns of cells in v1 that prefer input from one eye over the other

Question 9

what are blobs in v1

Answer 9

groups of cells involved in colour processing

Question 10

what is cortical magnification

Answer 10

more cortical space is dedicated to processing input from the fovea, leading to higher visual acuity

Question 11

what does the visual cortex hierarchy look like

Answer 11

v1 (basic features) -> v2 (more complex patterns) -> v3/v4 (form and colour) -> v5/mt (motion)

Question 12

what does v2 do

Answer 12

processes simple and moderately complex patterns (contours, illusory edges)

Question 13

what does v4 do

Answer 13

involved in processing colour and form; it shows strong attentional modulation

Question 14

what does v5/mt do

Answer 14

processes motion

Question 15

what does damage to v5/mt do

Answer 15

causes motion blindness (akinetopsia)

Question 16

what did patient lm suffer from

Answer 16

akintopsia due to a stroke damaging v5/mt

Question 17

what were the implications of lm illness

Answer 17

couldn’t pour coffee, or cross the street, or walk in crowds

Question 18

what is akinetopsia

Answer 18

see the world in a series of still images

Question 19

difference between dorsal and ventral streams

Answer 19

dorsal = where
ventral = what

Question 20

what is dorsal (where) stream responsible for

Answer 20

motion and spatial info

Question 21

what is ventral (what) stream responsible for

Answer 21

object identity and detail

Question 22

what happens if ventral stream is damaged

Answer 22

difficulty in object recognition

Question 23

what happens if the dorsal stream is damaged

Answer 23

difficulty in spatial awareness

Question 24

what is blindsight

Answer 24

the ability to respond to visual stimuli without conscious perception due to v1 damage.

Question 25

what is balint-holmes syndrome caused by

Answer 25

caused by parietal lobe damage

Question 26

symptoms of balint-holmes syndrome

Answer 26

they can describe objects but have trouble interacting with them

Question 27

example of ballint-holmes syndrome

Answer 27

able to identify a slit but have trouble posting a letter through it

Question 28

what is the binding problem

Answer 28

challenge of how the brain integrates features processed in different areas (colour, motion, shape) into a single coherent perception

Question 28

what is the grandmother cell theory

Answer 28

the idea that a single neuron could respond to a complex object (e.g. grandmother)

Question 29

what is opponent coding

Answer 29

the brain compares signals from cones in ratios to perceive colour

Question 30

what are the three types of cones

Answer 30

L-cones (long wavelength) M-cones (medium wavelength) S-cones (short wavelength)

Question 31

what do L cones respond to

Answer 31

red

Question 32

what do M cones respond to

Answer 32

green

Question 33

what do S cones respond to

Answer 33

blue

Question 34

what is meant by red + green = luminance

Answer 34

L cones(red) and M cones(green) are both sensitive to brightness, so adding their signals together gives a measure of overall luminance (brightness) of the scene

Question 35

what is happening in red/green (red vs green)

Answer 35

the brain compares how much the red cones are firing vs how much the green cones are firing

Question 36

what happens if red > green

Answer 36

the object looks reddish

Question 37

what happens if green > red

Answer 37

the object looks greenish

Question 38

what happens if red = green

Answer 38

the colour is neutral (grey or yellowish)

Question 39

what is meant by red + green/blue = yellow-blue detection

Answer 39

red + green = yellow so this ratio is asking how much yellow vs blue is there

Question 40

what happens if red+green > blue

Answer 40

you see yellow

Question 41

what happens if blue > red+green

Answer 41

you see blue

Question 42

what happens if red+green = blue

Answer 42

you see a neutral white or greyish colour

Question 43

why does the brain use ratios for colour recognition

Answer 43

so brain can keep recognising colours even under different light conditions - colour constancy

Question 44

do cones fire more as brightness increases

Answer 44

yes

Question 45

what is colour constancy

Answer 45

the ability to perceive colours consistently despite changes in lighting

Question 46

where does colour constancy occur

Answer 46

V4

Question 47

how does visual information travel from the eye to the brain

Answer 47

retina -> optic nerve -> optic chiasm -> optic tract -> LGN (thalamus) -> V1

Question 48

where is the LGN

Answer 48

the thalamus

Question 49

why do we detect changes in light rather than overall light levels

Answer 49

ganglion cells respond to contrast and edges, rods and cones respond to different light levels

Question 50

what is a receptive field

Answer 50

the area of the retina that influences the firing of a particular ganglion cell

Question 51

why is more cortical space given to the fovea

Answer 51

because it provides detailed vision and has the highest visual acuity, a larger portion of the cortex processes its input (cortical magnification)

Question 52

what is the fovea

Answer 52

central part of the retina where your vision is the sharpest

Question 53

why does the cortex magnify inout from the fovea

Answer 53

the brain prioritises detailed vision. you need high-res processing for tasks such as reading and recognising faces

Question 54

An OFF-centre ganglion cell responds best to:

Answer 54

a spot of light shone only on its surround

Question 55

The “where” visual route is also known as:

Answer 55

dorsal pathway

Question 56

The primary visual cortex is also known as ___.

Answer 56

V1

Question 57

Which of the following statements best describes rods? A. Functional in dimly lit environments B. Wavelength sensitive C. More numerous at the center of the retina D. High visual acuity

Answer 57

A

Question 58

Which thalamic nucleus receives visual information from the retina?

Answer 58

lateral geniculate

Question 59

how can vision reach parietal in blindsight patients

Answer 59

via the superior colicus

Question 60

why does blindsight occur

Answer 60

v1 damage

Question 61

how thick are hyper columns

Answer 61

approx 1mm of v1 cortex

Question 62

why do ganglion cells respond more to contrast than brightness

Answer 62

they are designed to detect edges and changes in light, which helps identify object boundaries

Question 63

what is the role of the receptive field in detecting edges in vision

Answer 63

ganglion cells respond differently when light hits the centre vs the surround, helps to detect edges

Question 64

purpose of the receptive field

Answer 64

helps to detect edges

Question 65

why is V1 considered a retinotopic map

Answer 65

spatial layout of the retina is preserved in V1 - nearby points in the retina activate nearby neurons in v1

Question 66

what is the importance of ocular dominance in depth perception

Answer 66

it allows the brain to compare input from each eye, which is important for stereoscopic vision

Question 67

what is stereoscopic vision

Answer 67

3D vision

Question 68

how do hyper columns in V1 contribute to the brain's ability to analyse complex visual scenes

Answer 68

cell orientation and ocular dominance info for a single retinal location, enabling detailed analysis

Question 69

functional significance of cortical magnification

Answer 69

allows the brain to allocate more processing power to the centre of gaze, where detail is more important

Question 70

which brain area is the first cortical region to process visual information

Answer 70

V1

Question 71

what type of neurons in V1 are sensitive to specific line orientations

Answer 71

simple cells

Question 72

what are simple cells

Answer 72

respond to edges, gratings, and specific orientations in the visual field

Question 73

what is visual agnosia

Answer 73

an object recognition deficit

Question 74

why might visual agnosia occur

Answer 74

damage to ventral stream

Question 75

what pathway is associated with identifying faces and objects

Answer 75

parietal

Question 76

which structures carry visual info from the retina to the LGN

Answer 76

optic nerve, chiasm, and tract

Question 77

which visual area is especially responsive to attention

Answer 77

V1

Question 78

which structure is key in the reflexive orientation to visual stimuli

Answer 78

superior collicus

Question 79

which pathway leads to the temporal lobe

Answer 79

ventral stream

Question 80

what type of cell fires based on the spatial layout of light on its receptive field

Answer 80

simple cell

Question 81

what is a bipolar cell

Answer 81

a type of neuron in the middle layer of the retina, between rods, cones, and ganglion cells

Question 82

what is the feature detection theory

Answer 82

the idea that humans have specific cells responsible for detecting features such as edges, lines, and colours